How was Napoleon's invasion of Russia supplied?

Question: How was such a great army, like the army of Napoleon on its way to Moscow, supplied with food and other needed things? Were they transporting it from France or maybe stealing from territory on their way? What were general methods to supply great armies?
Comment: Your question is interesting. However, equally interesting question is "How chain of supply of Napoleo army failed during the winter in Rusia". You question assumes that his chain of suply was always successful. This was apparently not always true.
Comment: The legend has it that inventor of canned food came to Napoleon with his invention just before Russian campaign. Napoleon refused to use the canned food in his troops. And that this eventually was one of the reason of failures of his food supply during the winter. Never knew if this legend was true.
Comment: @Andrei: This seems only partially correct. According to Wikipedia, [Nicolas Appert](https://en.wikipedia.org/wiki/Nicolas_Appert), inventor of [canning](https://en.wikipedia.org/wiki/Canning), applied in 1806 to the French government for award of its 1795 contest prize of 12,000 francs for an improved food preservation method. Initially denied, likely because no-one knew how the method worked, that decision was reversed in 1810 on condition that Appert publish the technique. He did, but production problems prevented widespread use until after 1815,
Answer: Campaigns of Napoleon: The Mind and Method of History's Greatest Soldier by
David Chandler is a good source of informations on Napoleon.  See pages 749-797, chapter "War Pans and Preparations".
Mostly, the supplies were stored and ran from Poland.  However, the army was accompanied by no less than 200,000 animals and 250,000 vehicles.  A lot of the supplies were to be found on site -- hence the delay in the attack.  The sheer scale of Russia and its scorched earth were massive factors in the failure of the offensive.
Comment: More vehicles than animals, in an age when vehicles were pulled by (often multiple) animals?  That doesn't add up
Answer: Napoleon's army got some supplies from occupied and allied territories of course, especially from Prussia and Poland. Still, the distances were too long to get sufficient supplies in and so the soldiers plundered villages on their way to collect food. This turned out particularly devastating on their way back: the Russians used scorched earth tactics and the army literally starved to death. To quote Wikipedia:

Napoleon and the Grande Armée had developed a proclivity for living
  off the land that had served it well in the densely populated and
  agriculturally rich central Europe with its dense network of
  roads. Rapid forced marches had dazed and confused old order
  Austrian and Prussian armies and much had been made of the use of
  foraging. In Russia many of the Grande Armée's methods of
  operation worked against it. Forced marches often made troops do
  without supplies as the supply wagons struggled to keep up. Lack
  of food and water in thinly populated, much less agriculturally dense
  regions led to the death of troops and their mounts by exposing them
  to waterborne diseases from drinking from mud puddles and eating
  rotten food and forage. The front of the army would receive whatever
  could be provided while the formations behind starved.
Answer: There were four main methods of supplying troops during the Napoleonic period;
(1) The individual soldiers would be issued with rations that they carried in their knapsack. Enough for about two weeks. This was often in the form of what was called "biscuits" by more like a dense bread.
(2) Cattle or other animals were herded along and slaughtered along the way but these increased the grazing requirement.
(3) Wagons following in the supply train. The main component of which was normally flour. Periodically they would stop construct ovens and bake biscuits. (In Spain, Wellington's supply was mainly on mules rather than wagons)
(4) Living off the land and foraging. French armies tended to rely on this much more than the various allied armies. In western Europe this was much more successful than in less rich regions like Spain or Russia. While foraging can often enable armies to move faster, the prolonged use of foraging brings down good army discipline as troops get very used to this foraging and just outright looting follows and result in bad relations with civilians.(As well as opportunities for the less committed soldiers to just desert)
For the 1812 invasion of Russia, it was gathered in eastern regions under Napoleon's control and sent to the areas the Army was concentrating in. This was by wagon mainly but there was some use of river transport. Napoleon never intended to march to Moscow. The campaign was a series of ad-hoc decisions by Napoleon to move further into Russia which he had not planned for and had not the supply to do. Napoleon only had the wagon capacity to supply around half his army that sort of distance, and that's ideally. There were problems right from the start. Horses were not in good condition when they started (and the French cavalry were notorious for their bad treatment of their horses), and the extravagant use and marching of Murat was not going to conserve horses.
On the retreat from Moscow, the shortage of horses was made worse by poor march discipline, with much looted baggage that consumed both space on the road (making for more congestion slower march) and use of horses. Napoleon had been urged by his Generals to abandon much of the artillery (particularly those of the less useful smaller calibres) to free up some horses but this was rejected.
Comment: I plan to get back and explain biscuits and typical supplies carried in pack and few other things
Comment: French soldiers were typically issued cheese as well as biscuit for their ration. Both foods are both dense and calorie rich.
Answer: Napoleon's centre of gravity for his army was fast mobility and forced marches. Therefore, he enforced training for his troops to live and forage off the land. This worked within Europe where fertile lands made this practice easy. Organising his army into corps and regiments, he was able to ensure a fluidity and freedom of movement within the battlespace. This is more exceptional when you take into account that he faced enemies with the same technology (peer to peer).
Russia was a different matter entirely. The invasion was planned during 1811 in Germany. He crossed into Russia in 1812. His estimation of the campaign was that, due to his 600,000 troops, the Russian Czar Alexander would immediately surrender. He estimated it would take a total of three weeks.
The Russian generals knew they could not beat Napoleon head on. Already knowing his tactics and taking advantage of his need to bring Russia to heel quickly, to ensure the reinstatement of the effectiveness of his "continental system", Russia's troops kept withdrawing further into Russia. Only taking part in small skirmishes in order to ensure the French army never relaxed. Then Russia stated to commit to scorched earth, burning the winter's crops so the French could not utilise them.
When Napoleon got to Moscow he had 300,000 troops (some historians say 200,000). The Russians burnt Moscow to deny Napoleon the ability to rest and recuperate there. Napoleon withdrew from Russia trying to avoid the scorched earth, however, the Russians attacked Napoleon's army forcing them to go back through the scorched earth areas. When Napoleon eventually got back to Germany he had a meagre 30,000 troops.
Napoleons Russia campaign is not so much a lesson in failure of logistical systems more so a lesson that an army must always strive to eliminate any weakness within logistical systems as there is nothing that will control how an army can utilise a battlespace more.
Comment: inaccurate on number, Napoleon had barely 100,000 on entering moscow, Napoleon losses on machine to moscow were greater than those when retreating.  Who burnt moscow has never been proven, the Russian fired some military stores, but haphazard looting bytes french army began straight away and fires from such lotting were common. Though much private supplies being in cellars survied that fire, there was no attempt to impose march discipline and loot was favoured over food in the retreat.
Answer: It's 3 years earlier, and a defensive rather than offensive campaign at least to start, but Volumes I and II of Saski's Campagne de 1809 en Allemagne et en Autriche contain considerable correspondence to Napoleon/ and Berthier outlining the preparations being made to arrange supplies in Bavaria for the 1809 war. In addition to numerous correspondences regarding the assembly of troops and munitions, there is detail on the quantity and location of ration stores being arranged across Bavaria. It's clear from this that the French Army of the time relied less upon living off the land than is normally supposed.
Two examples include from Volume I:

and Volume II:

....
Some key French phrases above are:

quinteaux de foin: quintals of hay
quinteaux de paille: quintals of straw
boisseaux d'avoine: bushels of oats
paires de souliers: pairs of shoes
rations de biscuit: biscuit rations
quinteaux de farine: quintals of flour
rations aux Bavarois: rations to the Bavarians
Des fours pour 60,000 rations par jour: Ovens for 60,000 rations per day

where 1 quintal would likely represent 100 kg weight
Answer: Tinned food was in its infancy and expensive to employ, the tins were sealed with lead and would not have been used on such a massive scale.
Napoleon's armies divided to march, United to fight and thus tried to live off the land/local produce and used supply wagons/depots more closer to the battle when concentrated.
One of the reasons supply failed in Russia was the Russians destroyed everything and then the road Napoleon wanted to take was barred on the retreat forcing the army to retread the same barren route. Also severe heat then storms on the advance killed thousands of horses and so many of the wagons were abandoned.
Comment: Sources would improve this answer.
Comment: Sources would greatly improve this answer.
Comment: See my comment above on the question. Appert used glass jars rather than tin for his canning; and no-one else used tin n any widespread scale until [Bryan Donkin and John Hall](https://en.wikipedia.org/wiki/Canning#In_the_United_Kingdom), did so for the Royal navy starting about 1817 - after the Napoleonic Wars had ended.


If I'm using milk as an ingredient in soup, how can I prevent it from curdling?

Question: There are numerous chicken stock based soups that also have milk as an ingredient  and the milk always seems to curdle - how can I prevent this?
Answer: Milk curdles due to acidity, so if you can raise the pH of the soup by adding something basic, it would help, although it could affect flavor.
The other thing to try is heating the milk to ~90 degrees C before adding it to the soup. This will cause the protein in the milk to change in a way that curdling won't result in as bad a final result--it may in fact appear that the milk hasn't curdled at all.
You can also "temper" the milk (as mentioned by Ocaasi): add a bit of the soup to the milk first; then add the milk-soup mixture to the soup at large.  And yes, higher fat milks will tend to work better.
Answer: Try adding the milk separately to only a single cup of broth.  Stir thoroughly.  Then slowly add this to the pot.  It will allow the milk to come up to temperature gradually in a less acidic environment.  Also, higher fat milk will be less likely to curdle, in case when you said milk you meant something other than milk.
Answer: You might also try using cream instead of milk; I'm not sure I remember the technical reasons but it is much less likely to curdle. You would want to use less of it than the milk, but it won't introduce the possibly unwanted sour flavor of creme fraiche.
Answer: For protection against heat, you can stabalize the milk with starches.  (eg, a white sauce made with milk won't curdle, even if you boil it).  I unfortunately don't know how much you'd have to add, and of course, it'll end up affecting the texture of your soup).
For soups, you're likely better off making a corn starch/milk slurry before adding the milk, so you don't have to cook it like you would flour to get rid of the raw flour taste.
You may also want to consider the heat that you're cooking the soup at -- you likely want a low simmer, not a full boil.
Answer: you can also possibly experiment with creme fraiche, which won't curdle, but the flavor is different (nuttier, but not as sour as sour cream) than milk, but at least you won't have the curdling problem! :)
Comment: The reason that crème fraiche won't curdle is because it already is curdled!  I think this is the same reason that heating the milk (which denatures some of the protein) seems to prevent curdling: because you are in a way pre-curdling it.


How to securely share your Amazon wish list with only certain people

Question: On Amazon is there any way to share wish lists with only certain people? I can make a list public or private and I can share it, but can I make it public to only certain people can see it?
Answer: As of now, no.  However, the only way other people will see it is if they specifically search for you using your name or email address - If you want it to be private, just change your name to something else, and link only the friends you want to see it using share, and let them know the reasoning behind changing your name so they don't think you're insane.  If you want it really, really private, change your email address associated with the account.
Hopefully Amazon will add a feature like you described in the future.
Answer: https://www.amazon.com/gp/help/customer/display.html?nodeId=501094
Public: Anyone can see it.
Shared: Only people with a url/link to your list can see it
Private: Only you can see it


On-topic Off-topic Leader Board

Question: I'm perceiving a class of problem that I don't know is really there, so I'm posing this as a feature request but would like to see some discussion if anyone else has an opinion.
Problem: The process of voting on individual exemplary questions isn't always aligned with the goal of producing the set of questions that define a site.  The system is designed so that participants discuss and vote on individual questions as though that were equivalent to discussing and voting on this aggregate object "the definition of the site".  This equivalence is true in many cases but not all of them.  I'm calling this the individual/aggregate problem.
The simplest example I can think of is astrology questions on the astronomy site.  There are multiple astrology questions that are off-topic and they are receiving appropriate off-topic votes.  The voting is going exactly as it was designed.  However, if these questions each survive the discussion period instead of having 10 different dimensions of off-topicness represented in the defining questions, there will only be eight (assuming the other questions aren't degenerate with each other).  A precious limited resource used for defining the site is being allocated sub-optimally.
I realize we have a tool for dealing with this particular instance of the I/A problem (deleting duplicates EDIT: Actually I don't even know if this is a feature), but there are probably going to be other instances that don't have simple solutions.
Proposed Solution: My proposed solution to help deal with all instances of the I/A  problem is to create a view that shows only the 20 on/off-topic questions by which the site would be defined if it were created today.
It would provide another way to bring the duplicate problem to light and would also show other schizophrenic behavior such as two questions that are essentially the same on both the on and off topic lists (This is a just another instance of the duplicate problem, I'm having problems coming up with other instances of the I/A problem if you can't tell).
In addition to hopefully helping to deal with the I/A problem this feature just seems like something that is simply missing from the site.  If one of the goals of the discussion period is to produce this site definition it seems odd that there isn't one place to go to find out how that's progressing.
Comment: This would be a cinch if Area51 had an API.
Comment: ...or was in the data dump.
Answer: There should be a way to close them as duplicates and aggregate their votes
Comment: So far, that's manually commenting with a link to the duplicate and voting Meh.  Everyone else has to switch their votes manually, though.  Not sure automating the vote switching is desirable.

On-topic Off-topic Leader Board


What to take out from the results of Jun 2013 Site Self-Evaluation

Question: The results have been announced for Let's get critical: Jun 2013 Site Self-Evaluation. So what can be deduced from those raw numbers? Is it good, bad? Or those numbers are actually not meant to be analyzed?
Comment: Hi Aziz, I picked one question and gave a write up on it based on what I see in the search results. There are of course other things we can do to fix these posts and make the site appear more attractive. Please feel free to self-answer if you have a specific question in mind where you see opportunities to improve. Thanks for posting this! :)
Comment: Hi @jmort253, I won't commit :) but I'll try to add a good analysis of a question just like you did below. However a more high level question, was this exercise done to bring out individual posts which can be improved or was is performed to find an overall rating of site's health/quality?
Comment: Hi Aziz, the self-evals are mostly for us (the community) so we can learn what areas, in general, to focus on in order to make our site be the best it can be. I'm sure the [community management team](http://meta.stackexchange.com/questions/99338/who-are-the-community-managers-and-what-do-they-do) looks at them as well, but we'll get the most benefit from this exercise when we come up with more action items to help us move forward. Hope this helps! :)
Answer: I'll shed some light on how I look at these, as you can get some useful information out of them. I'm not going to dive into each question individually. The exercise isn't one to find content that needs to be fixed (though you can fix things you spot), it's more to determine how the overall quality of the site seems when compared to similar sites.
First , a bit about the evaluation itself - Google the heck out of some questions that were asked and see how we stack up to sites that serve the same topic, then rate it on a scale. It's a rather subjective undertaking and I've found ratings (across more than a few sites) to be more overly critical or accurate than not critical enough. That is to say, I've seen some pretty good content a few folks thought could use improving. The old adage you're your own worst critic and all, so keep that in mind as you interpret the results.
Here, in no specific order (or maybe, a secretly specific order, I won't tell!) are the things I look at when these evaluations close:
Turnout
Out of sixty three people that earned badges for regularly using the site, four participated in the self-evaluation. Evaluations are a big 'ask' of folks, so let's say that only 20% of regular participants would be interested in the activity (roughly 11 people). That gives us around a 37% turnout. It would have been nice if 3 - 5 more folks participated to get a broader sampling. The turnout wasn't horrible, but it could have been better.
Take away: Set a goal to boost meta participation a bit more. Open and feature some more interesting discussions as opportunities present themselves. If you have a half baked idea and think 'that could be neat' - go ahead and toss it out.
Evaluation - First Glance
My first pass doesn't involve any clicking, I just look at titles to see if they adequately describe what's behind the link. These are how people find you through searching, so it's important to make them descriptive.
You did really well here, the only ambiguous title I saw was:

Catch up scheduling

Take away: Keep manicuring and curating your content like you have been doing - you're doing a great job in that department
Evaluation - Deeper Pass
This is where I do exactly what you did, and I get really nerdy serious about it. I fire up a virtual machine which is basically a new computer and I start searching question titles to see what I come up with. 'Personalized' search results really do get in the way of these, so I highly recommend incognito or private browsing mode when you do them.
Overall, I felt that the content here exceeds or at least matches the quality of information I was turning up on the blogs, forums and (occasional) productivity software sites that I found. I thought a few were a little more toward excellent than satisfactory, but those that participated gave it a very honest go.
Take away: Besides the turnout, the result of the evaluation was overwhelmingly good. Fix whatever you've identified, and just keep doing a good job when it comes to curating.
That's really all there is to it - just a periodic check to make sure you're producing better or at least comparable quality as similar sites. You are. We can say yes, it's meant for analysis, but don't read too much into it.
Comment: Thanks Tim, that was really helpful. Good to know that PMSE is doing good on the content quality front (partly due to the tireless efforts from PMSE mods). We definitely need to increase traffic and participation on both Main and Meta sites. Also +1 for recommending incognito or private browsing mode for searches to do self-evaluation.
Comment: Hi Tim, thanks for helping answer this question and provide us with a few more goals to shoot for. We really appreciate you taking the time to provide this guidance! :)
Comment: Thanks for the context and analysis.
Answer: The "Balancing Software Development" Question
Question: How to allow developers to get enough quality development time while keeping to support & maintenance obligations
If you Google "balancing software development and software maintenance", there are resources on this subject. On page two of the search results is Jeff Atwood's post on the subject, The Noble Art of Maintenance Programming.
Jeff's article is great, but it doesn't quite answer the question as directly as our post does. Jeff does an excellent job explaining from a high level overview that maintenance and new features should be treated as one in the same, our posts actually explains how one might achieve that goal using project management and agile methods.
The problem is that ours is buried so deep that I don't even see it on page 5, and while searching "how to balance software maintenance with new development" I get similar results, except Jeff's post is on page 3 instead.
Fortunately, this particular problem is very fixable. If you have edit privileges, ask what edits we can make to increase the posts' visibility on the search engines. 90% of a heathy site's traffic comes from search engines, so by making content such as this easier to find, we increase our visibility.
Also, we should consider whether it would be better to post the asker's "update" as a community wiki answer, since it makes the actual question look really really long.
I went ahead and posted the updates in a CW, but in the future, we should catch askers who do this and ask them to post their updates as individual comments on the applicable answers. Each paragraph in his update is basically a comment on a specific answer.
If you all think it looks silly to have the updates in an answer like that, let me know and we can revert it back.


How do I transfer files to ebook reader from phone using either an OTG cable or wifi?

Question: I've a rooted Sony reader PRS-T1 (based on Android 2.2) and usually when I need to copy files to it, I connect it to my laptop with a USB cable. However, sometimes I travel without my laptop and have only my phone/tablet.
I tried using an OTG cable, but my phone does not seem to be able to read the reader storage.
Is there a way of transfering files to my reader from my phone without using an external sd-card?
In the past I used to connect to Dropbox in the reader's browser to download files or send the files thorugh gmail, but the browser is very old and this is no longer possible.
Answer: Now there are plenty of ways to do this;  perhaps the easiest method given that you have the OTG cable, is just to use a suitable file explorer (preferably MiXplorer which has custom OTG drivers) in case your storage device is formatted in a different file system.
I wrote a guide on MiForum on how to achieve this:  Alternative easy way to mount Pendrive(NTFS FileSystem) via OTG without root its not only limited to ntfs but can also use others like exfat etc.

In your case you just need a USB Flash drive (pendrive) that you can insert on the OTG female port then,
Simply open the app, tap on the three dot menu → More settings → Enable Custom driver for USB OTG (tick the box to enable).
Done, now insert you OTG cable and place the pendrive on the port. The  pendrive will  be recognised without errors, and open the files you need  and copy to and fro the tablet <=> phone as you wish.

Alternatively I have posted a related method here, showing how to do it using wi-fi (which is pretty much related to what you're trying to achieve):

Android to Android file explorer using wifi direct

Or

File transfer with linux pc through mobile hotspot
Is there a way to access the phone filesystem from computer, wireless?

(In above cases the target tablet will be the pc or "second android device" respectively)
Hope this helps
Answer: I found a working wireless solution using FTP. The reader has Total Commander installed and there's an FTP plugin you can install for it.
So on my phone, using Amaze File Manager, I created an FTP server (protected with username and password). Then on the reader I added the details of the server and I could copy the files to my reader with ease.


How to choose between two equally good and equally helpful answers

Question: I posted a question here and got two equally good answers. Both of them are short, useful and to the point. One person's answer is more upvoted than that of  the other which I believe was due to the former answering much earlier than the latter. Both of them responded equally to my comments and doubts regarding both methods, thus putting more effort into it. Now I am in the moral dilemma of whom's answer I should accept?
Comment: I guess you didn't use both answers for your initial purpose, why not thank the one who actually helped you? Additionally, as stated by Jubobs, you can thank explicitely the answerers. I personally see accepting more as a semantic flag "this question has a definite answer", than as a reputation reward or a "thank you" for the answer itself. The "thank you" is given by your upvote and maybe a comment, while the rep. reward is given by the upvotes (sometimes complemented by a bounty).
Comment: Related: [Choosing to accept between an answer that helped me the most and a more popular answer](http://meta.tex.stackexchange.com/q/3176/5764); [Should I switch the accepted answer?](http://meta.tex.stackexchange.com/q/3570/5764)
Comment: Also, I seriously doubt any of the answerers would question your choice. They know that both answers are equally good, and they know that you can only accept one of them.
Comment: No worries, we just don't care, in fact it's the common theme of teasing each other in the chat room. You can join us too if you like.
Comment: If it's a tie, I think not giving the checkmark to one rather than the other is acceptable. Simply explain your dilemma to both answerers and thank them for helping you.
Comment: I think It's fully in your control and you can be better judge. Leaving appreciating comments to other answers like Peter suggestion is good idea.
Answer: The answerers know that you can only accept one answer; they shouldn't mind when you do so.
On english.stackexchange, I've been an answerer in this scenario many times, and I've never seen anyone unhappy when one answer among two or several good ones was accepted.  If you like, a comment like "Thankyou, this [was very helpful/works fine/is a useful alternative], and I wish I could accept it as well as X's answer" never goes amiss — while "thankyou" comments are deprecated in general, in this situation it gives useful extra information for readers.
Comment: What I mean is more: if your choice is a bit arbitrary, that doesn't really matter — it isn't a big moral dilemma.  So yes, you can flip a coin if you want; although I've never seen two answers so exactly equally good that I didn't have *some* slight leaning towards one of them.
Comment: I believe your answer is on the presumption that I am confused whether one answerer will be offended if I choose the other. But the problem is not that. The question is on what basis should I choose one of them. Since comparison of helpfulness and technical value is ruled out, what should be my next point of comparison? Should I just toss a coin then :-) ?
Comment: you are right!, I did have some inclination towards one of the answer as I thought it was more cool and which I accepted as an answer. But, then still the question remained for a hypothetical situation other than that of mine, where they are exactly equally good. Thanks for the reply.
Answer: If the two answers are absolutely of the same value, I think it could be a good practice to accept the one of the user with the lowest reputation.
In general, you should vote/accept the answer, not the answerer, but when there are two equally good answers, I think it is better to reward the user with the lowest reputation. It could be a way to make him/her more affectionate to TeX.SE!
Comment: Better is to not display reputation at all. Reputation display decreases the quality of the site, because it infantilizes its users. In the same vein, there should be a delay of 24 hours before the submitted answers actually show. 1) this would increase the long-term quality of questions, avoiding the build-up of "oh gosh I don't know what to do, I have never ever read any docs, let's ask on tex.stackexchange", 2) this would allow the OP to compare more serenely the answers and not validate the first one which happens to solve his/her problem.
Comment: @jfbu I don't look at reputation with such a pessimistic view, it could be also a (raw, of course) method to measure the answerers' reliability. 1) I don't either agree with the idea of the delay in submitting answers, our first goal is to help users, as quickly as possible. 2) On the other, I agree with the fact that users often accept the first answer, not the best (and more often don't accept answers at all) but the delay is still not a good idea, in my opinion.
Comment: in most cases, the user will accept the first answer which "solves" the problem; but the user was not qualified to solve the problem him/herself, and sometimes, its estimation of what actually has been solved might be erroneous. The current functioning of the site is not one of educating the public. It does not help increasing the average understanding of LaTeX and friends by users. I am quite convinced an objective assessment of quality of questions will conclude to a decline over the years. A delay of 24 hours would help reduce the user base to a less consumeristic one.
Comment: @jfbu A delay of 24 hours would help make the users ask elsewhere :)
Comment: precisely my point `: )`. There is a small community here of experts, including probably 3 or 4 (make that 10 `;-)` ) among the top few world connoisseurs of LaTeX, and I find it a bit wasteful to observe them reply to questions which nowadays, very often, are from people who did not make any effort to read even a modest amount of documentation.
Comment: @jfbu That is really a pity!


How to set the tempreture at which the fan must speed up - laptop

Question: I have HP Probook 4530s and the fan speeds up at around 45C then when it reaches 35C slows down and repeats. In the interval between 35-45 it barely works and this results in very annoying speed up of the fan every 2 minutes. How can set a higher threshold at which it will speed up and how can I keep the tempreture between the two intervals stable ( I mean the fan will not turn off but keep a steady speed ).
Thank you in advance.
Comment: possible duplicate of [How to control fan speed?](http://askubuntu.com/questions/22108/how-to-control-fan-speed)
Answer: Fan speed and the temperature at which the fan hits certain speeds can be controlled in linux via a combination of packages lm-sensors and fancontrol, though on my HP laptop I could never get it to work properly, I believe because HP controls this via the bios, but it may just be I didn't research enough.
I ended up changing the cpu governor to conservative and changing the conservative governor settings this ultimately made my computer run cooler and more efficiently (less fan cycling).
I found these two pages that helped me manipulate the governor and put my setting permanently in /etc/rc.local to load them on each reboot http://www.pantz.org/software/cpufreq/usingcpufreqonlinux.html
http://www.thinkwiki.org/wiki/How_to_use_cpufrequtils


How will insurance work for manned commercial missions?

Question: I know that commercial satellite missions have insurance, but will they cover the same thing for manned missions? Has there been any sort of publication talking about this sort of thing?
Comment: Depending on the legal jurisdiction, I would guess they would require a combination of insurance and waivers as rocketry and space travel may be absolute liability activities that are inherently dangerous from an insurance and legal perspective. (Much like many adrenaline sports and other dangerous hobbies) Insurance companies need a combination of limits and sufficient actuarial data to provide coverage.
Comment: As for publication, I don't know, but I hope I provided some additional terms to search on the topic. It is an interesting question.
Comment: The concept of at least partial indemnification for private companies bold enough to perform manned launches from American soil is one that should be robustly explored/considered by the federal government.  Wisely done, I'm thinkin' it would be a fine use of public funds.
Answer: So obviously some of this is going to vary by jurisdiction, and none of it is really worked out yet, but here is where things stand.
There are various kinds of insurance.  The first kind is insurance to cover loss; this is what satellite owners get, for example, to cover themselves in case their satellite is destroyed during a failed launch.  Second would be liability insurance.  That is, insurance to cover damages you might cause to someone else.  We'll need to address those two kinds of insurance separately.
Generally speaking, current requirements for insurance are minimal.  The FAA requires U.S. launchers to get liability insurance that covers the launch and first few months of the operation of a satellite, but nothing beyond that.  That's right: there is no requirement of liability insurance beyond about 90 days.  Under the Outer Space Treaty, ultimate responsibility for paying damages rests with the launching state (the country itself, even for commercial things), so if we're talking about a U.S. origin launch, eventually it is the U.S. Government that essentially "insures" against liability.
As far as insurance against loss, that's up to individual operators.
So that's how things are now.  For newly-contemplated space activities, such as commercial human spaceflight, on-orbit servicing, etc., there is not a well-developed insurance market at all because of an almost total lack of actuarial data.  The ultimate government backstopping provided by the Outer Space Treaty also decreases the incentive for private insurance.
Eventually, someday, launching states are going to want to require insurance by commercial companies so that they won't be putting their own taxpayers on the hook, but that will impose costs, and there is the risk of chasing operators away to jurisdictions that are willing to require less.
So that doesn't totally answer your question I'm afraid, but it's because the best answer is something like "yeah that's a good question."
As far as a paper on this, I know there have been a few symposia and things of that nature.  https://www.scor.com/en/media/news-press-releases/overview-space-insurance seems to provide some information as well.
Edit: I should also say that individual states (Here I mean federal states within the United States, such as California, not states in the international sense) could certainly impose additional requirements on companies operating out of their territory.
Finally, to answer the very specific question about liability for potential harm that might come to commercial passengers, I anticipate that being handled through waivers for some time, with eventually some liability insurance to cover operators, but again, there is no actuarial data for this, so it's not really available now.  Presumably you could throw enough money at an insurance company that they would give you a policy, but at that point you might as well just self-insure (simplified idea: keep a pot of money set aside to pay claims).
Comment: Done!  https://space.stackexchange.com/q/25981/12102
Comment: [Might ISRO's 2018-004 launch be at least a technical violation of the Outer Space Treaty by India?](https://space.stackexchange.com/q/25981/12102) has an answer already, may be of interest. [What regulations, agreements, or other forces can help mitigate "PrankSats"?](https://space.stackexchange.com/q/18201/12102) seems firmly closed though.
Comment: The very quick answer is absolutely, yes, that could be a violation of a handful of different obligations in the Outer Space Treaty as well as the other space treaties.  I see that issue as going significantly beyond the original question about insurance, so if I have a chance to talk in detail about that elsewhere, I'm happy to do so.  Just joined a few days ago, otherwise I would have weighed in on those earlier questions.
Comment: The "elsewhere" might be just posting an answer to it. (I'm assuming that by "it" you are talking about the ISRO question).


Why was this edit rejected?

Question: I made an edit to an answer that contained a list with a repeated item. My edit was rejected because it "deviates from the original intent of the post". Why would that be?
Comment: Also, editing an answer of a user with 370k rep from 2009 makes non-robo reviewers wary.
Comment: For what it's worth, I've applied the spirit of the edit in another fashion; one that avoids repeating information and also preserves what the original intent of the original post was.
Answer:
TL;DR: Assume that everyone reviewing your edit has tunnel vision, and is looking at only the red & green and maybe the line directly above and below it. They'll only look elsewhere if you explicitly tell them to in your edit comment.

Your edit was rejected because three people weren't paying enough attention. You have to understand, most reviewers don't really pay attention. Reviewers are trained to look at red and green, and only red and green.
All they saw was this:

and this:
Comment: duplicate list item

Now, they look at that second thing, then looked at the red color and the 'list' around it. They never saw the list item above the code block.

That answers 'why' it was rejected. What you really want to know, though, is how you get these approved. I would have written the comment like this:
Comment: Remove duplicated list item - see the item above the code block. The item I deleted was already mentioned.

You should stand a slightly better chance of having your edit approved if you're explicit, even painfully so, about what you did and why you did it.
Comment: Without this answer I would've never found the duplicate item.
Comment: @KevinGuan You'll notice that I never excluded myself from that group either :)
Comment: *They'll only look elsewhere if you explicitly tell them to in your edit comment.* Agreed 100%.  Even folks trying to be super diligent can miss things from time to time.  Although I sometimes spend several minutes on a review decision when the comments are very vague, I am sure I have missed stuff too.  Best way to guard against that is tell the reader up front exactly what you changed and why :) Not everyone will agree, but ... at least the reasoning behind it will be clear.
Comment: @Makoto No worries, it took me a few glances to figure out what was up here as well :)
Comment: @dramzy It would help if Undo used instead the "markdown" output instead of the rendered one... is *eye opening* ;)
Comment: Makes sense. I guess I looked at the answer for too long to notice that the code block would distract someone from the first list item.
Comment: I would vote to reject that edit if I'm one of the reviewers because...okay, I'm a bad reviewer.
Comment: This is the correct answer.  I seem to be having an off weekend on Meta...the edit really shouldn't have been rejected.
Comment: The takeaway from this answer and these comments is that edit reviewers need to spend more time reviewing suggested edits
Comment: @TylerH Definitely. That's hard to enforce, though.
Comment: Well, if I were one of the three people not paying attention – the following would be the reason: the code block below the first bullet is misaligned, making this look like two lists of one and three items respectively.

Why was this edit rejected?


Why are the Trojan libration points equidistant and not mass weighted?

Question: The locations of the collinear Lagrange points L1, L2, L3 are mass weighted, so for example Sun-Earth-L1 is only 1% of the distance to the Sun from Earth. But L4 and L5 are one AU from both the Sun and from Earth. Shouldn't Earth's gravity be negligible that far away? Are L4 and L5 another kind of phenomena than L1, L2, L3?
Comment: Maybe because L4, L5 are in a stable free fall orbit, like Earth is. And then mass doesn't matter? But being on a straight line between Earth and the Sun, then mass does matter alot.
Comment: They are mass-weighed relative to the Sun - in exactly the same mass-distance relation as Earth is.
Answer: From Wikipedia (emphasis mine)
The reason these points are in balance is that, at L4 and L5, the distances to the two masses are equal. Accordingly, the gravitational forces from the two massive bodies are in the same ratio as the masses of the two bodies, and so the resultant force acts through the barycenter of the system; additionally, the geometry of the triangle ensures that the resultant acceleration is to the distance from the barycenter in the same ratio as for the two massive bodies. The barycenter being both the center of mass and center of rotation of the three-body system, this resultant force is exactly that required to keep the smaller body at the Lagrange point in orbital equilibrium with the other two larger bodies of system. (Indeed, the third body need not have negligible mass.) The general triangular configuration was discovered by Lagrange in work on the three-body problem.
Also from the article:
Comment: I'm not following why you think "the force is the same", nothing I have posted implies that. The point is that the **ratio of the forces and masses** is the same.  Maybe you aren't familiar with the triangle of forces concept? https://www.easycalculation.com/trigonometry/learn-triangle-law-of-forces.php
Comment: I think I get it now, finally.
Comment: I somewhere miss you there, Organic Marble. Barycenter is very close to Earth' center of gravity. ESL4 is obviously too far away from Earth or our gravity to be important over there, compared to that of the Sun. Is it the orbital movements relative to Earth and Sun that evens it out?
Comment: Sun/Earth barycenter would be close to the Sun, no?
Comment: "Same distance". So why isn't 0.5 AU a Lagrange point linearly between Earth and Sun?
Comment: I'm not sure I can say it better than the wiki article...to me it all comes down to the triangle of forces.  In the L4 case the ratio of masses and forces is the same, so the resultant force points through the barycenter.  In the linear case, the "triangle of force" collapses to a line and the distances involved are proportional to the masses.
Comment: Just fantastic that Earth can wield the same force 1 AU from here as it can 0.01 AU from here. Fantastic, energy for free!
Comment: Because the magnitude is different. Shouldn't the "triangle" have one side that is 100 times longer than another side?
Answer: The brief answer is that the L1 and L2 points are different in the sense that the gravity of Earth exerts a far more significant force on objects at L1 and L2. Earth's gravity is about 10,000 times stronger at L1/L2 than L4/L5 and 40,000 times stronger than at L3.
Objects at L3, L4 and L5 are orbiting the sun at very nearly but not quite exactly 1AU. They naturally orbit in about 365.25 days, would continue to do so if the Earth was zapped out of existence. Earth's gravity isn't exerting much force on them.
In contrast, the heliocentric distance of L1 is about 0.99AU and L2 about 1.01AU. Normally an object at 0.99AU would orbit the sun in about 363.4 days and an object at 1.01AU would orbit the sun in about 367.1 days. But at L1 Earth's gravity partially counteracts the Sun's gravity - by about 3% - sufficient to allow an object to orbit in 365.25 days despite being closer to the Sun. And at L2 the Earth's gravity adds to the Sun's - again about 3% - sufficient to allow an object to orbit in 365.25 days despite being further from the Sun.
Here's a neat webpage on the ESA site with animations and detailed descriptions
Okay so what's the difference? Any object at very nearly 1AU and not too close to Earth will maintain its position relative to Earth relatively well for a time span measured in decades, although over time the cumulative effects of Earth's gravity will perturb the orbit. L3 is more stable and L4 and L5 are stable infinitely for idealized 3 body.
In contrast any object with a semi-major axis around the Sun of 0.99AU or 1.01AU will normally very quickly change its position relative to Earth, being at least 2 days ahead or behind the Earth within a single year. The exception is L1 and L2 where the gravity of the Sun and Earth combine such that an object with a suitable velocity and minor station-keeping can follow an orbit synchronized with Earth's. In that sense, the L1 and L2 points are pretty special and Earth's gravity plays a much larger role in their stability.
Comment: There it is again: "L1 and L2 where the gravity of the Sun and Earth balance perfectly…"

At L1 sun's gravity is about triple earth's gravity.

At L2 both the sun's gravity and earth's gravity pull in the same direction. So they reinforce each other rather than cancel each other out.
Comment: Wouldn't any object anywhere in Earth' orbit have a stable heliocentric orbit? If you by station keeping mean to compensate for influence from Jupiter and Venus passing by, I still don't see why anything special should happen when the Sun and Earth distances are equal. And for every planet and single moon regardless of masses. Actually I think Jupiter's gravity is more influential at the Trojans 1 AU from Earth, than is that of Earth. 317 times more massive, only 4½ to 6½ times further away. It's not as if Earth has a 2 AU wide Hill sphere, right?
Comment: @LocalFluff actually at all locations within Earth's orbit except L4 and L5, Earth's gravity itself will gradually perturb the object, until it crashes into Earth/Luna, or is flung out of orbit by Earth. The L points are defined in terms of the 3 body problem so this is true independently of the influence of 4th bodies. In reality it is true that other bodies may have a larger perturbing effect, but that is beside the point to the theory of Lagrange points.
Comment: This answer is incorrect. Look at L2 -- From L2 both the orbiting body and central body are pulling in the same direction. So obviously gravity from the two bodies aren't canceling out. The L points are where gravity from the two bodies and centrifugal force cancel out.
Comment: @HopDavid what I intend to mean is that in the absence of Earth's gravity the object at that distance from the sun would need to take a faster (or slower) orbit around the Sun in order to maintain a circular orbit.
Comment: Of course SEL1 would orbit faster in the absence of earth's gravity. That doesn't fix your answer. Gravity does **not** cancel out. Downvoting.
Comment: @HopDavid I believe this is a legitimate way of looking and it corresponds closely to a gravity simulation (i.e. calculate force vectors, add them up). I've edited my answer to be less L1-centric and hopefully more strictly accurate.
Comment: @HopDavid Oh I get it, you're using "balanced" in the strict physicists sense as in balanced vs unbalanced forces, and I'm using "balanced" in the sense meaning "in the correct proportion". I would use "add" but that's even more prone to misinterpretation, "combine" seems to be the safest word choice and is whats what Wikipedia uses.
Answer: It's a tug of war between three accelerations: Central body gravity, orbiting body gravity, and centrifugal acceleration (inertia in a rotating frame).
Centrifugal acceleration is $\omega^2*r$ where $\omega$ is how fast the system's spinning and r is distance from barycenter.

In the case of L1, centrifugal force and orbiting body gravity are on the same team. These two exactly cancel central body gravity. In this case all accelerations are parallel or anti-parallel.
At L4 and L5 none of these forces are parallel.

Centrifugal pushes away from barycenter. Central body's gravity pulls towards center of central body. Orbiting body's gravity pulls towards center of orbiting body.
The way to add vector forces is to put the foot of one vector on the head of the other vector. The sum is a vector from from the first vector's foot to the 2nd vector's head.

Adding the two gravities we get a vector that exactly cancels centrifugal acceleration.
If we shrink the orbiting body's mass, barycenter moves closer to center of larger body. Central body's gravity becomes more dominant and the orbiting body gravity vector gets smaller. But the two gravities still sum to cancel the $\omega^2r$ which points from barycenter to L4.
Comment: So, in a Sun-Earth system, a lower mass Earth would pull lesser on the L-point object. But then also the barycenter would be nearer the Sun. So those two even out exactly, so that L4, L5 always describe equilateral triangles? *(It's as if some Greek mathematician created the universe)*
Answer: Let's start by looking at the equations of motion for R3BP.
$\ddot x -2\Omega\dot y-\Omega^2x = -\dfrac{\mu_1}{r_1^3}(x+\pi_2r_{12})-\dfrac{-\mu_2}{r_2^3}(x-\pi_1r_{12})$
$\ddot y+2\Omega\dot x-\Omega^2y = -\dfrac{\mu_1}{r_1^3}y-\dfrac{\mu_2}{r_2^3}y$
$\ddot z = -\dfrac{\mu_1}{r_1^3}z-\dfrac{\mu_2}{r_2^3}z$
Where $\pi_1 = \dfrac{m_1}{m_1+m_2}$ and $\pi_2 = 1-\pi_1$ are the mass ratio, $\Omega$ is the angular velocity of reference frame wtih respect to inertial frame; $r_1$ and $r_2$ are distances of third body located at $(x,y,z)$ from $m_1$ and $m_2$ respectively. And the center of coordinate axes lies at the barycenter.
Your solution for $L_4$ and $L_5$ (trojan points) comes from equilibrium condition thus $\dot x= \dot y = \dot z = 0$ and $\ddot x = \ddot y= \ddot z=0$. Which on solving gives
$x = \dfrac{r_{12}}{2}-\pi_2 r_{12}; \hspace{10pt} y = \pm\dfrac{\sqrt{3}}{2}r_{12}; \hspace{10pt} z = 0$
The remaining 3 points solution requires moving one step further by imposing the constrains $y=0$ and $z=0$ and solving the following polynomial for given mas ratio to obtain $\gamma$
$\dfrac{1-\pi_2}{|\gamma+\pi_2|^3}(\gamma+\pi_2)+\dfrac{\pi_2}{|\gamma+\pi_2-1|^3}(\gamma+\pi_2-1)-\gamma = 0$
giving 3 unique solutions; where $\gamma = \dfrac{x}{r_{12}}$
If you look at $L_4$ and $L_5$ the $y$ coordinate the general solution tells you that they lie along the vertex of an equilateral triangle with other two vertices lying at two masses. This is because the function $\pi_2$ is generally $<<1$ so $x$ becomes essentially $r_{12}/2$. Thus they are function of majorly $r_{12}$.
This unique geometric position enables the force acting on $3^{rd}$ body to pass through the barycenter, which essentially makes it motionless wrt to one of the bodies as seen from other. For better understanding you consider two bodies of comparable masses, then your barycenter position $\rightarrow r_{12}/2$ and your mass ratio $\pi_2 \rightarrow 1/2$, so your $x$ becomes zero. Based on vector diagram it is easier to see that net force will then pass through the barycenter in such case.
So all points are equilibrium points and none of them have something special attached to them.
On effect of Earth gravitation at $L_4$ and $L_5$, using Newton's Law  we can show that on a unit mass at those points  $\dfrac{F_e}{F_s} = 0.000003003 $. This small yet significant force arising due to Earth changes the application of resultant force on unit mass to act on barycenter instead of pointing directly at the focus (the Sun center).


Laminating 2x4s - brush on the glue?

Question: I laminated some 2x4s for workbench legs, and as you can see by the attached picture, there's a gap between two of the boards. I applied the glue in a zig zag line down the length of the boards and then a line along all 4 edges of the board's face.  I clamped the 3' long glue-up with 5 clamps that I tightened pretty securely. I'm wondering why this gap exists, and what I can do better next time, since I still have to glue up the entire top.  I did glue up all four legs at the same time, so will take the previous advice to do a pair at a time from this point forward.  I don't think this is a problem structurally, but maybe next time I should brush on the glue smoothly?  Maybe I should be planing these flatter to start with? Thanks.
Comment: The gap looks pretty obvious. Was it evident when you dry-fit and clamped?
Comment: Not enough clamp pressure! If you're doing a full panel like this in the future, clamp each subsection one at a time. Even if it means you're glueing up three or four separate times it's important for solid glue joints that will be dependable in the long term. Oh and here, in case you don't realise you're going to need to separate the boards with the gaps (saw them apart), clean off the glue, then re-glue.
Comment: I admit I was rushing to clamp everything because I clamped up four assemblies like this at the same time, so it was 12 boards together with the same clamps which I was manipulating in a very small space. I should've checked more carefully and taken my time.
Comment: Plane the mating faces a bit to get rid of any very high points.   You need a lot more clamps and a lot more pressure, maybe a clamp every 10 inches or so, alternating from above and below.  A lot of people will say to only glue up 2-3 boards at a time but in my experience it is just as easy to glue up to 6 at a time.  The glue is not going to set for around 10-15 minutes.  Anyway gluing those up 2 at a time wouldn't solve the problem anyway, the gap is large enough to fit a quarter in, it needs a lot more clamps.
Answer: I have several suggestions for gluing this type of slab.

The glue does not spread itself.  Always distribute it evenly before making contact between pieces.  You can do this using a brush or a roller.  I keep a rubber ink roller to distribute glue in large areas and then simply rinse it to clean off the glue for its next use.
Glue on both contact faces will insure maximum contact better than on only one face.
Run the bottom of the boards through the jointer to insure the base of the slab is flat so that the pieces will set flat during and after gluing.
Do not glue and clamp all the pieces at the same time.  These pieces are larger and it will take a lot of pressure and a lot of clamps to make full contact between all the pieces.  For a 2x bench slab like this I would plane the contact faces of two boards, glue them together, let them set, plane the outside faces and then join the pairs together  and then repeat for the 4 piece slabs until done.
Use plenty of clamps (1 per foot would be nice).
Once the slab is as wide as possible for your planer, runt the joined sections through the planer. (This will reduce the amount of hand planing needed to get the top surface flat and eliminate the ridges caused by the milled edges of the original 2xs
Answer: Looking at the ends of the boards in the first photo you can see that they are tight at the bottom, but not at the top.  It looks to me like the faces of the boards that you glued together are convex (i.e. the opposite of cupped, not sure what the correct term is).  It might also be that they're twisted.
Either way I think the solutions is better milling beforehand.  You can't really rely on construction lumber being straight or flat, and clamping it into submission isn't always possible.

Laminating 2x4s - brush on the glue?


Why is C++ still a very popular language in quantitative finance?

Question: I had to ask this question after reading the answers to What programming languages are most commonly used in quantitative finance? I understand that C++ programs can be optimized pretty well and are faster than anything else. But in this era, the performance of a program written in a language based on frameworks such as C# and Java can be pretty close to that of C++, while the maintenance cost of the program would be lower than the C++ one. But why is C++ still a very popular language in QF?
Comment: @chrisaycock the previous question only answers this question tangentially.  I agree it is borderline, but I believe this question can stand on its own, especially in light of the excellent answers given here which mention information not given in the previous question.
Comment: @Belmont I actually found one faq in this site that says C++ is the most popular one in QF. That led this question. But I don't mind moving this question to more appropriate site. Please do so if necessary.
Comment: I am very tempted to close this question, and indeed there are a couple votes already to close it. **The [question you cite](http://quant.stackexchange.com/q/306/35) already answers this question!** C++ is popular because (1) the boss pays people to use it, and (2) data vendors have, at least historically, only provided proprietary APIs in C++.
Comment: @Taesung: Could you give the reference? Or perhaps you should change the question from "still the most popular" to "still very popular".
Comment: @vonjd Updated my answer with the reference.
Comment: Alright, this question has run its course. I find it embarrassing that our most viewed question on this site is just speculative and doesn't even represent what quants do. And on a related note, anyone who asks strangers on the Internet what language he should use is a terrible programmer.
Comment: IMO This question is inappropriate for quant.SE.  You provide no evidence that it in fact *is* the most popular language.  Please search the site for other programming questions to see how this has been discussed in the past.
Comment: I did read those parts of answers but I wanted to clarify or dig into more details. I think I got what I wanted so don't have any objection to close.
Comment: @BlackJack where did you post the link to this question to get it so many views?
Comment: I think he mainly posted the link here ( http://hackerne.ws/item?id=2934042) Interesting discussions there over this weekend. I guess chrisaycock was interested in this question after all.
Comment: @Taesung Do you understand why we prohibit beginner questions? Because we don't want a couple dozen non-quants offering their totally speculative "answers". The SE is meant for people *in the industry*, not hacker wannabes who want to write about topics they clearly don't understand. Ever since your question hit HN, we've been slammed by rookies who want to debate C++ vs Java and who want to know how to break into the business. And I, the moderator, am receiving flags from anonymous newbies who don't like the way the C++ vs Java debate is going!
Comment: @chrisaycock God forbid that somebody should flat THE MODERATOR!! ;-)
Comment: Java does its optimization while the code is running, meaning that you'll have a few moments of sub-par performance while the code is being analyzed. It that sense, C++'s execution speed is more "constant." C++ memory management is more convoluted, but you know where and when the overhead's coming. There is an optional garbage collector component in the new C++ standard; we'll see how much it's used.
Answer: The other posters have already noted that the prevalent use of C++ appears to be due to historical reasons and unwillingness to change. Those reasons aren't the ones that people should be applying. If you want real reasons to use C++, how about the following:

Powerful infrastructure. Take a look at Intel Parallel Studio for an example.
Performance compared to .Net or Java (see my course on HPC). When each array element access checks the bounds and throws exceptions, you know you're leaking CPU cycles there.
Parallelization. The C++ ecosystem has vastly superior paralellization in both 'blind' mode (OpenMP vs TPL's Parallel) and explicit mode (Intel TBB vs TPL)
Lots of SDKs, most notably CUDA, base their development on C/C++.
Possibility of invoking low-level CPU instructions (e.g., work with SSE intrinsics).

On the other hand, C++ is

Extremely noisy. What with all the headers, include directives, friend class declarations, and myriads of other redundant things.
Has hard-to-use libraries (STL, Boost) with very cryptic, global-level mechanisms. Think bind_2nd :)
Editor support is vastly inferior compared to IDEA/ReSharper. Navigation, refactoring, analysis - all are weaker or non-existent. This is going to be improved in the near future for both VS and standalone editing.
Compiler errors are beyond cryptic. Clang attempts to fix it to some extent, but things are still cryptic, just not as abysmally bad as they were previously.

And by the way, for the typical user, the performance difference between C++ and, say, C# won't be as pronounced.
Comment: "When each array element access checks the bounds and throws exceptions, you know you're leaking CPU cycles there." This is not true. JIT will remove plenty of array bound checks. Pure computational performance (ignoring memory allocation/deallocation) under .NET runtime (ignoring vectorization) is pretty close to the performance of raw C++.
Comment: I concur with Mehrdad wrt Java. I was easily able to engineer Java-based quantitative trading models that were just as fast as C++. I worked in both languages at different firms and can tell you that well-written Java can be as fast as C++.
Comment: @Dave I suspect you've been comparing near-identical code, which doesn't reflect the fact that in C++ you can explicitly use SSE. I also suspect (haven't tested) that OpenMP beats Java parallelization (unless you handcraft it) just the same as it beats .Net's TPL.
Comment: @user492238 almost all C++ code I've seen that used SSE (graphics and physics engines) use compiler intrinsics. When I played around with SSE, I also used intrinsics.
Comment: @Dmitri Nesteruk "Compiler errors are beyond cryptic", clang largely fixes this.
Comment: Thanks for your answer. Indeed, I didn't know there is still that much difference in performance. Then, I guess it's obvious to use C++ for especially QF systems.
Comment: What do 'editor support' and 'compiler errors' have to do with the language? These are editor and compiler issues, respectively.
Comment: @James let me generalize then: *all* editors are pretty bad and *all* compilers give unreadable error messages.
Comment: @Dmitri Nesteruk 'in C++ you can explicitly use SSE' yes but you wouldn't really often, right? You would rely on the compiler to do so for you. And this is, what the Java user does.
Comment: @user492238 I don't know about Java, but AFAIK .NET does not vectorize its operations to take advantage of SSE. No idea of Java does this or not. And the point is not just to use SSE yourself, but to take advantage of libraries written by people who *did*.
Comment: @Dmitri Nesteruk Right. I was just wondering, if this argument counts pro or against C++? Since to interface a library API is easy and recommended - from within almost every language?
Comment: @user492238 This is a Pro-C++ argument because the C++ compiler is supposed to vectorize more. I use a vendor-specific compiler (Intel), so I trust it to generate instructions taking advantage of my specific processor. Yes, performance will suck on AMD, but then I'm not sharing code :)
Comment: @Dan Does the Quant community use Clang, though? I had the impression that most stick to Microsoft C++. I'm an Intel C++ user myself, but am very tempted by C++ AMP.
Comment: "Has hard-to-use libraries (STL, Boost)" what? STL is not hard-to-use
Answer: The main reason is traders/quants currently in business often learned C++ in their formation rather than C#, they naturally used this language when starting new projects.
It will gradually evolve, I guess you could have asked "what's the reason cobol is still the most popular language in Finance" 20 years ago.
Also most projects in production use C++ but I think now most new projects gradually evolve towards C#/Java.
Comment: Cobol analogy makes sense. I wondered if there is any hidden reason I missed.
Comment: This is a good point: I've been forced the write something in C# the past month because an API was only available in C#. They claimed C++ was supported, but gave no usage examples, and basically refused to answer C++ related questions.
Comment: Maybe, but modern C++ libraries such as Boost (and everything added to TR1/TR2 and C++11 derived/inspired by Boost) have made C++ much more of a palatable language to use.
Answer: Garbage Collection.  The amortized performance between C++ and more modern languages is similar, but when your heap gets large, a GC can still take 100ms or more!  That's an eternity, and just isn't acceptable for anything with real-time requirements
Comment: Honestly, 100ms is absurd for garbage collection.  Something like this is more the relic of poorly profiled code.
Comment: Agree! Latency is a key factor in QF application.
Comment: @Todd HFT is only a subset of QF.
Comment: You can have garbage collection in C++ too, so it can't be cited as an advantage of Java. Java often forces an unflexible paradigm on the user on the ground that "they know better", while C++ lets you free to adapt wisely. Unsurprisingly Java was repeatedly forced to backstep and readopt features of C++. Security of Java also turned out to be vastly exhaggerated.
Comment: Garbage collection is indeed a huge concern but keep in mind that you always have control over when garbage collection will happen.  It's a balance between suffering from memory leaks and having to have a system that may need to be tuned.
Comment: I agree on Michael RB.
Comment: exactly, when I do coding in C/C++ I feel like "I AM programming", when in Java I feel like this is not mine, or in .NET that they suggest/more suggest/WANT me to use their hints. no, no. I don't like it. only C/C++
Answer: I don't know if it the most popular but it is popular for sure - I think there are several reasons for that, which not only apply to QF:

It is a mature language with many years of development behind it
There are many people who are able to program it
Many books, tutorials, websites, communities are available (network effect!)
It is fast
There are many libraries available (also math and quant-oriented) - and it is transparent what happens within these libraries (which is sometimes not the case with proprietary higher language toolboxes and systems)
There are sophisticated free compilers which make it possible for academia and basically everybody to start exploring the language
It is a hybrid with which you can - but need not - program in an object-oriented way
The resulting code can run on its own but can also be connected to other programming systems

There are few languages out there that have all of these characteristics - but there will finally be a transisiton at least towards C# and Java (This is already happening).
Comment: To sum up your answer: "Risk aversion" ;)
Comment: @wburzyns: There is this saying concerning computers: "Never change a running system" ;-)
Answer: People use C++ because it offers a balance between performance and convenience. It is true that you can get Java to be (almost) as fast as C++, but you need to put a lot of effort into it. On the other hand, an average-quality C++ code will be much faster than average-quality Java code. I know this from personal experience.
Comment: @user492238 Subjective, like all the discussion about this question.
Comment: I wonder how to define "average-quality". Is this on a subjective scale, taking into account personal bias?
Comment: @user492238 average is described here as expected value [EX](http://en.wikipedia.org/wiki/Expected_value) where X is time of execution of the choosen program
Answer: Whichever treasury system the banks implements it will have pieces in C/C++ and/or Java. So C++ is just easier to interface.
Also, as little as the difference of performance is, it does matter if you need to plug that model in a Montecarlo simulation running hundreds of scenarios -  for value at risk computation.
Comment: However I have read that with language like Scala and JIT compilation the performance of Java VM can be very competitive compare to C++. Perhaps that will catch up.
Answer: Not all will agree that "the maintenance cost of the program [is] lower than the C++ one." For just one thing, when we use C# or similar, we have to wrestle with the C# "framework," which aims, but often fails, to deliver a "richer," "more powerful" development environment. But "richer, more powerful" is in the eye of the language designer or design committee and often translates, on the mat, to "a briar patch of needless complexities, obstructions, irregularities, dead ends, unexpected stupidities, counterintuitive rules, and lazy, dumbass assumptions."
C and C++ (and, yes, assembler) present no such hurdles, which considerably eases programming and maintenance.
Comment: very interesting view. Even if somehow... well: subjective ;) You obviously spend much more time on C/C++ then you did on C#. And this is no critism. But it could explain your bias towards C. I remember every language at the beginning seemed to be build out of "counterintuitive rules".. ;)
Comment: You don't find C++ to be full of "needless complexities, obstructions, irregularities, dead ends, unexpected stupidities, counterintuitive rules, and lazy, dumbass assumptions." ? Maybe you're thinking of C and extrapolating.
Answer: The optimization possibilities offered by C++ templates can make code potentially very fast; faster than C, and faster than Java could ever hope to be. (A C programmer will typically use a function pointer and a compiler cannot inline that; a C++ functor can and will be inlined.)
I know C# has templates that look like C++'s but I cannot personally comment on speed benefits. C# is too closely tied in with Windows. And Windows is not a good platform to build financial systems on (IMHO, but also that of the LSE and others ;-) And don't get me started on DLL Hell when you try to mix APIs from two companies...
[Feb'13 UPDATE: Ironically I've done a lot more C# in the year since writing that. (And that is an indication of its growing support, even going so far as some companies offering a C# API instead of a C++ API.) C#/Mono works well (but the people offering C# APIs are foolishly not testing on Mono and letting needless Windows dependencies in; foolish because it limits their potential audience). Finally, C# templates are instantiated at run-time, so it is not possible to do those the C++ compile-time optimizations.]
I do agree with others that the tide may be turning against C++, but C++11 may give it a new lease of life. The speed and power is still all there, but the auto keyword and the built-in lambdas (to name but two) can make the code look much cleaner (meaning easier to maintain and harder to introduce bugs).
Finally, as a reason to use C++ in finance, there is Rcpp and RInside !
Comment: templates != speed increase.  Sometimes templating can result in increased inlining, which can sometimes increase performance.  There are also template metaprogramming techniques that can increase performance.  C++ speed advantages mostly comes from the excellent compiler optimizing, and the fact that there is no GC or interpreter.
Answer: Its because the people still "think", it must be faster and hence favor C++. Real arguments are sparse. Some of the most ideological arguments:

'Bound checks on every array element access.' But in relevant loops they can be removed in C# and are automatically removed in Java (Hot Spot VM) and CLR often.
'GC is slow.' Yes it is slower on collecting garbage. But allocations are much faster then in C++! And VM language developer are made to implement pooling strategies to circumvent allocations nearly completely. This, at the end, is even faster than the frequent new/delete in C.
'SSE instructions only in C++.' Partly true for .NET. But instead of optimizing the very end of uniprocessor performance, one should rather optimize the memory usage, which is a real challenge for our common large datasets and by far the biggest reason for slow execution nowadays.
'Superior parallelizm.' How that? OpenMP & Co use the same system resources and synchronization constructs which are available to, lets say, .NET as well. It is - as always - up to the user to utilize them in an efficient way. Especially if it comes to thread level parallelism higher level languages provide more comfort to be written.

At the end, every system is heterogenious. The choice of a language for a specific task should not be biased by the personal experience too much, but rather reflect the abilities of the language to get the work done fast and reliable. I would not use C++ for user interfaces anymore. C# is better at that - and equally good for many tasks which were assigned to C++ uniquely in the past.
Comment: 2: see my comment above on GC: you can do GC in C++ if you want, while you can't easily avoid it in Java. C++ lets you free to chose according to the situation, while Java forces a suboptimal allweather compromise (also in other cases, such as unsigned).
\\
3: red herring: again memory usage is surely critical, but that's true in all languages, and the ability to *additionally* optimize calculations is a clear plus. Impeding FP performance optimization does not improve memory usage in any way, so why should that be good?
Comment: Ah, I forgot, some SSE instructions even specifically target memory performance optimization!
Answer: I will focus on some of the many reasons why we prefer C++ to Java, while I dont have much experience with C#. First of all various answers here have brought up valid points on why C++11 is way more practical than other languages, once the learning phase for advanced features is mastered, especially for large numerical projects, so I need not repeat things like why having control over GC is a significant advantage.
Java is mostly geared towards an OO paradigm, while C++ additionally offers functional programming and a very powerful template metaprogramming framework (Java generics are not really comparable, neither do C#'s templates do significantly better afaik).
For numerics various Java issues can be a burden, such as the absence of unsigned integers (although this has been corrected at last) or slow performance of trigonometric functions.
Let alone access to SSE/AVX, and the lack of control over bounds checking. And operator overloading in Java is also not really supported: can you really write any numerical code without that?
And every Java object occupies at least 8 bytes, which has become a significant overhead with memory access becoming slower (especially in machine learning, but I bet in HFT too).
Missing adressing also renders many data structures unnecessarily heavy, and some are even impossible to implement in Java.
The virual machine sometimes pollutes the code cache too, then there's class loading and other overheads...
Also the absence of function pointers is an issue, and the "alternative" Java idioms have their drawbacks.
Furthermore afaik multithreading in Java is not so practical, and is shifted down to multiprocessing (please correct me here).
Interfacing to other languages through JNI is a real pain (or atleast so was at the time when I had to).
As far as I know there's no advanced library comparable to Eigen in Java or C#, for example; new HPC projects are still dominated by C++, and these are only some of the reasons.
Java and C# for sure are more convenient for other tasks and have a much softer learning curve, but so do even VBA or plain old Excel.
Also check this related comment.
Comment: Do you actually use Eigen as a quant?
Comment: Not in the current project since they're still stuck with legacy code, but I've used it with full satisfaction in the past (and plan to do it again whenever possible). I also know some people deep in the HPC linear algebra R&D world, and their way more competent appreciation is significant. Unfortunately quants cannot always carry out a throughout comparison before adopting a lib (and many dont even have the numerical background to do so), so historical reasons dominate technical considerations, but my impression is nevertheless of slow but steady adoption growth.
Answer: C is tought at courses at universities everywhere. And people invested many time and efford to get into it. Now we want to collect the fruits and not reinvest into any new platform/language. But the IT world is changing so fast as does the computer architecture. "Next Generation" developers are used to handle C# and Java even more than C++. And they are getting tired of changing platforms - if everything they need is already there. I have switched to Visual Basic 6 years ago and didn't regred so far.
Answer: I do agree with the argument on historic reasons, speed and GC with regarding the original question.
To add my 2 cents to the rest of the discussion, I believe that Scala/Akka combination will gain a strong foothold in QF. Of course Languages like Erlang did exist long before Scala/Akka, but did not get much footing due to its esoteric nature and cryptic syntax (at least for people familiar with C/C++ like languages) and not many used it. Scala syntax is also cryptic but there is a growing user base and IB and funds have started using it.
Also another language to watch-out is F#.


How do we determine the temperature of a Black Hole?

Question: How do we determine the temperature of a Black Hole?
Since we cannot see a Black Hole, which I presume, is because it absorbs light, would it not also prevent radiation from escaping, making temperature determination difficult.
Comment: Probably via entropy.. IIRC, if you replace 'entropy' and 'temperature' with 'horizon surface area' and 'surface gravity' in all the ThermoD laws, they check out for a black hole. The radiation becomres Hawking radiation.  Related to some fellow called Bekestein, IIRC. I would post an answer but I'm extremely unsure of this.
Answer: Classically, you're exactly right.
Quantum mechanically, something strange happens.  It turns out that the way that we define what a particle is and, therefore, what the vacuum is, is dependent on our notion of time--in particular, you are stuck with particles being objects that propagate information forward in time, rather than backward in time.
In general relativity, though, we know that the notion of time on a black hole horizon is inequivalent to that far from the black hole.  What this means is that if you take a vacuum solution far from the black hole, and in the distant past of the black hole, and trace it forward in time, you will find that by the time you reach the black hole, it will appear that that state will contain particles!  Furthermore, some of these particles will be travelling above escape velocity, and at late times, will be arbitrarily far from the black hole.  So, Hawking radiation is inherently a quantum mechanical effect deriving from the fact that the definition of a 'particle' is ambiguous in general relativity.
Furthermore, when you analyze this gas of radiating particles, you will find that it is exactly equivalent to a gas having a temperature that is proportional to the gravitational force felt at the horizon by an observer falling into the black hole.
Comment: @RonMaimon  Thank you all, for your answers. My main reason for the question, was the differences in temperature that have been given for different black holes. Generally black holes temperatures are given as very high, and then all of a sudden someone talks about a cold black hole. I think Wiki "Hawkins Radiation" explains this. I.E. Mass & CMB radiation balance. Are you aware of anyone developing a means to prove this? - NASA etc.
Comment: @Clive Ballard: What do you mean "prove"?  I gave you an outline of the proof.
Comment: Sorry, I did take on board what you said. Ron Maimon said much the same thing and so does (Wiki) - Hawking radiation. There are so many different satellites out there now, measuring different forms of radiation etc. When I said developing, what I meant was developing a system to look directly into a black hole, at a distance, and take its temperature. Probably not feasible, since that sort of information, is not escaping.
Comment: I am a layman, as far as much of this is concern, and I do struggle a little bit, to take it all in. That particularly applies to the quantum side of things. I have worked with logic all my life, and that probably explains why I do not get on, with the quantum theory. Though, I have no objection to it, if it proves a point.
Comment: @CliveBallard  Hawking radiation has never been directly observed, and likely will not unless you get black holes made in Earth-based particle accelerators.  The reason is that astrophysical black holes are likely to be extremely low in temperature, and at that point, the effects of quantum gravity, such as Hawking radiation, are likely to be extremely small.
Comment: Well I agree with you there. Nearer to absolute zero than CMB. Part of the reason for asking my question, was to see what response I got. I have no doubt, if I mentioned what I thought, I would get flamed.
Answer: The temperature is determined using the equivalence principle, and the temperature detected by accelerating detectors.
When a detector is accelerating forever in a certain fixed direction with acceleration $a$, it sees a thermal background temperature equal to $a/2\pi$. This thermal background is associated with the horizon that is formed by the accelerating particle, since a beam of light a certain distance away from the accelerated observer never catches up.
The reason is that an accelerated path is a hyperbola, because the acceleration is the curvature of the particle's path through space-time, and the curvature is constant, and in relativistic geometry, the constant curvature curve is a hyperbola, just as in Euclidean geometry it is a circle (this comes from the minus sign in the relativistic version of the pythagorean theorem).
The hyperbolic time coordinate is the analog of the angle in Euclidean polar coordinates, and if you formulate a quantum field theory for the accelerating coordinates, the imaginary time continuation is periodic with period $2\pi$, which means that the theory is thermal. This is a little technical, but you can just take Unruh's result on faith. For a free field theory interacting with a detector, like photons interacting with an accelerated atom, Unruh's result that the atom behaves as if it were in a thermal environment can be verified by direct calculations of the response of an accelerated detector, not just by fancy methods.
If you are near the horizon of a black hole, you must accelerate to keep from falling in. This means that you must see an Unruh temperature, by the equivalence principle. This Unruh temperature is in the "t" coordinate of the exterior, which turns into the Unruh angle-like coordinate near the horizon. This radiation must be self-consistent as you move away from the black hole, and the self-consistency condition is that the radiation is at a temperature which is smaller by an amount proportional to the rate at which clocks tick. the faster they tick, the colder the temperature.
When you redshift the near-horizon Unruh temperature to infinitely far from the black hole, you find a finite answer. This answer is $8\pi M$, or proportional to the mass of the black hole. This is equivalent to finding the analytic continuation of the black hole solution to imaginary time, and identifying the periodicity of this solution, and the reason is the physical argument above (since Unruh radiation is periodicity in imaginary time).
This argument has in the past been confusing, because most solutions do not have an analytic continuation. How does a physical temperature depend on analytic continuation? It doesn't really. The only thing that is used is the equivalence principle, to link the periodicity in imaginary time near the horizon (where it is just Minkowski space) to the periodicity far away. Mathematically, this is the same as the periodicity in imaginary time of the continued general relativistic solution.
These things are explained in a somewhat more complete and technical way on Wikipedia, under Unruh effect and Hawking radiation.
Answer: A black hole's temperature is given by:
$T = \frac{\hbar c^3}{8\pi kGM} \tag{1}$
So, if the mass of the black hole is known, normally by calculating the affect the black hole has in the surrounding space, you can calculate the temperature of the black hole.
Comment: why is this incorrect?


Stuck in windows start up failure loop, any hope or do I need a new HDD?

Question: Every time I boot my laptop (HP Envy 14) it goes to a start up failure screen and I have the option of starting windows in repair mode (recommended) or starting windows normally. either option freezes the computer at the windows is starting up screen, at a light blue screen that looks like the windows login background, brings me back to the start up failure screen, or, if i disable auto restart on start up failure, brings me to some type of blue screen of death.
I spoke to HP support and they told me to try and do a self hard disk test in BIOS. The test completed the first half but froze on the second. They then asked for the hard disk information in the main tab in BIOS but it is no where to be found. The Rep then told me to press f11 to do a system recovery but that brought me to another frozen screen. (attempting to boot into safe mode also brings me to a freeze screen). The rep then wanted me to get it sent in for HDD repair. This laptop is less than 2 months old! I see a lot of people with this problem doing a google search but all of the solutions involve booting from a clean install of windows disk (dont have) or booting into one of the modes that bring me into a freeze screen. I only have the recovery disks I made when I first got the laptop.
So, What do you guys think, is there anything else I can try or should I just get it warrantied. (2 months after purchase -_-)
Answer: If you know the HDD brand, try downloading the manufacturers test utility and see what that tells you. If the drive really is good, then do a recovery from your recovery disks, and see if you can get HP to send you a real oem Windows dvd. Otherwise, send it in if it's bad, because it won't get better.
Comment: Download the manufacturers test utility on my other machine or on the machine with the problem? < (not possible)
Comment: They test utilities are usually small tools that you'll need to boot from a usb stick or cd. Another option is to try Ultimate Boot CD, which is supposed to contain utilities from several manufacturers...http://www.ultimatebootcd.com. The utiliites will sometimes check your drive's firmware, letting you know if it needs updating. This could be the case here.


Django hosting on Windows server

Question: I'm running in a "Windows only" environment. We have a few linux boxes but we're not allowed to use Linux in our DMZ (something about it being less secure. ha.)
We're currently developing a couple of django apps as for a potential switch from Java running on Tomcat.
Since I have no choice in what server OS to use, what is the recommendation about what to use on Windows?
I've seen a lot of reference here to WSGI on Apache. I've heard of others running NGINX for the static files and FCGI for the django apps. What is the least complicated of the setup possibilities.
Answer: Please check this article - Running Django on Windows (with performance tests)

Django hosting on Windows server


DNS records serial number

Question: How important is it to change the serial number for every db.xxx.yyy record.  Can I keep the serial number the same for at least 2 records.
Thanks
Jean
Answer: No. You must change the serial number every time you make a change, and it must be a higher number than the previous one. This ensures proper propagation and loading for slave zones.
I recommend using a ten-digit serial, using the date (in YYYYMMDD format). Today would be 2011123000. Next revision today would be 2011123001. This allows for 99 revisions. The serial number will increment naturally using this method.
Answer: If you don't change the serial number, by the next zone transfer, the changes you've made will not be recognized (as the entire zone will be recognized as unchanged), and thus you might end up getting the updated records overwritten.
But it's only important if you want to maintain the changes you've made, if you just made them for fun, I'd say it's not important :-)
Answer: Please see the SOA notes here:
http://rscott.org/dns/soa.html
While technically the serial number should be updated, I find many people do not actually have multiple nameservers.  Instead, all nameservers run from the same server.  In this case, the serial number does not matter since the primary and secondary server are one in the same.
I however prefer to update the serial number using the YYYYMMDD date format as suggested by lunchmeat317 as this makes it easy to spot the last time you updated DNS.
Answer: It's only important at all if you have multiple content DNS servers replicating using the "zone transfer" mechanism.
… otherwise it's just frippery that nothing uses.  If you don't have multiple content DNS servers, you aren't replicating your database anywhere.  And if you are not using the "zone transfer" database replication mechanism, you very probably aren't using a mechanism that relies on anything in that entire resource record set in the first place.
I suspect that you are using "zone transfer" and have multiple content DNS servers.  But that's just an educated guess on my part, since you don't say in your question.  If so, remember that a change can comprise multiple resource records in one go.  Serial number updates are tied to changes, not to single resource records.
Further reading

Jonathan de Boyne Pollard (2004). The semantics of the fields of an SOA resource record.  Frequently Given Answers.

DNS records serial number


Relation between Orbital Inclination and launch site?

Question: Dear Friends,
             Is there any relation between inclination of injected orbit and the launch site ?
Comment: It's really not a good idea to edit a question and completely change its meaning. Best to add a new question.
Comment: Hi and welcome to the Space Exploration stack exchange.  People like to see some evidence of prior research here.  I suggest you take the tour https://space.stackexchange.com/tour . Also, check out the the related questions list that has appeared on this questions page or do a online search if you are stuck.
Comment: Just to illustrate the last comment and get you thinking on how to improve the question, the easy answer is "Yes, there is a relation, sometimes." If you want a better answer you will need to improve the question.
Comment: I agree: the edit completely changed the substance of the question.
Comment: I downvoted as in my opinion this question does not show any research effort. [Similar](https://space.stackexchange.com/questions/17679) have been asked before, and plenty of [things](http://www.orbiterwiki.org/wiki/Launch_Azimuth) to read online.
Comment: @PrzemekD I accept that !
Answer: Yes. While you can change your inclination over a burn, in a classic "plain" launch your starting latitude is the inclination peaks where your orbit is directly  above them relative to the launch site location. If you launch from Cape Canaveral and go "straight" from it with no immediate major change in longitude, the antipode will be the opposite coordinates, so 30°N is 30° south. And if you do have a change in longitude it makes your orbit even more inclined. If you do an inclination changing burn in ascent you can avoid any major inclination from launch sites' latitudes.
Answer: For a direct injection into orbit (i.e. no dog leg later), then by simple geometry, the orbit inclination will be greater than or equal to the absolute value of the latitude of the location of that injection, which is very close to the latitude of the launch site. A launch azimuth of zero (due East or due West) would result in an inclination equal to the latitude.
There may be further constraints on the inclination due to the allowed launch azimuth to avoid overflight of populated areas, or to provide telemetry coverage with available downtrack ground stations.

A nice illustration of dog leg maneuver during launch can be found in this answer, and dog legs are mentioned here, here, and here.
Comment: Could you elaborate on what you mean by a "dog leg" maneuver?
Comment: When you cross the equator some portion of an orbit later, you can do a maneuver to change the orbit inclination to a lower value than the launch latitude.
Comment: @Paul I've added some links to discussions of dog legs.


Progression through Eorzea

Question: I'm having quite a hard time looking for leveling spots in Final Fantasy XIV, and I was wondering if you guys can recommend an 'order of zones'.
Answer: In the old 1.x version of the game, there was no "order of zone progression" as in other MMOs like World of Warcraft or The Old Republic; each starting region has levequests, quests, and monster camps appropriate for players of all levels. There was content appropriate for levels 1-50 in each of the three nations, so it was entirely possible to level all the way to cap without needing to leave one's home region. It wasn't uncommon for various activties (storyline missions, faction levequests, parties, etc) to take a player to Coerthas and Mor Dhona, but strictly in terms of leveling, it wasn't necessary at all.
As this was a particular complaint among many players, all of the zones have been completely redone in A Realm Reborn. All of the regions are broken into smaller unique, more traditional "zones", and provide an intended order of progression as you move through the main story content. Figuring out this order isn't too complicated, as the main storyline and your class's hunting log will both guide you to the proper zones where you can find content appropriate for your level. Here's a rough list:
1-15: Depends on your starting city. Limsa Lominsa: Middle La Noscea, Lower La Noscea, Upper La Noscea; Ul'dah: Central Thanalan, Western Thanalan, Eastern Thanalan; Gridania: Central Shroud, North Shroud, East Shroud
15-20: Dungeons (Sastasha, Tam-Tara Deepcroft, Copperbell Mines); Eastern Thanalan, East Shroud, Upper La Noscea
20-25: South Shroud, East Shroud, Upper La Noscea
25-30: Southern Thanalan, North Shroud
30-35: Eastern La Noscea, Southern Thanalan, South Shroud, Central Shroud
35-40: Coerthas Central Highlands, Eastern La Noscea, Upper La Noscea
40-45: Coerthas Central Highlands, Mor Dhona, Northern Thanalan, Upper La Noscea
45-50: Mor Dhona, Northern Thanalan, Outer La Noscea
Answer: Someone (not me) created this map with the level ranges of each part of the zones.
It is primarily only useful for your 2nd or 3rd class, as going through the main story quests should get you the levels needed.

Progression through Eorzea


Laptop screen turns on by itself after turned off

Question: I just got this new laptop ASUS N56VZ, which has a rather strange feature. If I press fn+f7 to turn off the screen, it will be turned on by any mouse/keyboard event. If it's not a big problem itself(while never happened to my old laptops, and I don't like it at all), the most annoying part is that the screen always turns itself on right after I turn it off. And unplugging my mouse do solve the problem. I'm wondering if it's possible to disable this "feature"? "Allow the device to wake up the computer" in hardware settings of the mouse doesn't help(But my mouse does not wake up the system from sleep automatically, very strange). It's using Windows 8.
Comment: If you can't get the fn-F7 to work, you might consider setting the "close the lid" to not go to sleep or hibernate when on AC power.  Nice part about this is that the laptop continues to run and the screen is disabled and turns back on when you reopen the laptop.
Comment: I think Windows just gets lonely and wants attention.  But one thing to do is to go through all the gorp in Task Scheduler and delete/disable about half of it (eg, things like some app checking for updates every 10 minutes).  Those that you want to keep, set all but the critical ones to not wake the computer from sleep.
Answer: The problem might just be that your mouse is very sensitive and when it detects even the slightest jitter, your laptop then wakes up.  Try making absolutely sure that your mouse is not moving at all - even a tenth of a millimeter!  If in fact your screen does still turn on, your only recourse will probably be to turn off your mouse if it's wireless or unplug it if it's not.
Disabling "Allow the device to wake this computer" won't do anything, because this feature is not actually managed by Windows.  It's managed by your computer hardware at a baser level.  It's more like when a monitor on a desktop goes to sleep (yellow light) and turns back on when any input is given.
Answer: It's also possible that the trackpad is receiving input, make sure it's clean.
Perhapse get a mouse-bungie like gamers use, if the mouse is moving slowly or slightly because the cord has a springy effect or tension from hanging off the edge of the desk, its possible that it's moving indetectably slowly or slightly.
This used to wake my computer immediately after "sleep-display" as well.
Answer: Oh My friend I just found it now, if it constantly turns the Display on after fn+f7 go to your "power4gear hybrid" settings and from the last menu named "Enable/Disable" turn off Presentation mode. That would definitely solve the problem.