Game logic on the server! Good or bad?

Question: I'm currently planning a simple online multiplayer game. And here is the question. Does it make sense to make the whole game logic on the server and just send the input from the client to the server? Which are the pros and the cons or are there any reasons why I shouldn't do that?
Answer: You don't want to send player input to the server.  What you probably want to do is send an abstracted representation of what the player wants to do to the server, and then run the logic on there.
Likewise you don't necessarily want to send back everything the client needs to do.  For example, you can send some kind of message saying "NPC X died", and the client determines what animation/sounds to play.  Stuff like that.
The trick is to find the line where bandwidth and processing power (on the server) is trumped by preventing people from cheating.  Usually you make any kind of game-changing authoritative decision on the server only, and leave all the ancillary visual stuff to the client.
There are a lot of more specific questions on this topic all over the site.  For example:
Should collision detection be done server-side or cooperatively between client/server?
Who does the AI calculations in an MMO?
Should the game host be the authority, or another dumb client?
Comment: +1 Beat me to it. Also, depending on the style of game, you may want/need to do some client-side prediction.
Answer: Well, you got answers but your real answer is at "try yourself". The things differ from game to game.
I did couple of multiplayer games for some distributed network game design course. The most challenging was doing a realtime action game where many players involved and sending inputs like hell. When it comes to that point, everything becomes problem. As you see the first link Tetrat sent, even determining a collusion becomes a problem. And you will read-hear terms like lag, interpolation, extrapolation, prediction... But if you never tried yourself coding from scratch, you will just accept these words and wouldn't know what they really mean.
My recommendation is:
Step 1
Just start with fully authorized server based design for now. As you said, just send user inputs to server and let server do everything and clients get the results. Your game will work fully consistent. But when you look at your clients, you will notice some lags, some teleport problems, not smooth movement...ect.
Step 2
Start fixing the issues on client side. The teleporting problems for example. Your character was at (0,0) and server said now you are at (100,100). Your character will just teleport to (100,100) which is not nice. There comes the interpolation. You should have a code in client side which will slide the character from (0,0) to (100, 100) in a smooth way. Yes, you will move your character from (0,0) to (100,100) but how fast? For now you can just use the time difference between each server update. If your server sends 10 packets in a second which means 100 ms delay between each packet.
Step 3
Now your game is already  good for fast networks where there is delay of (1-50)ms. But it gets doomed if there is a packet loss, high latency or calculation takes long in server...ect. In those situations you will notice when you press left arrow, you will see your character moving left with a delay of 200 ms. The delay between your packet goes to server, calculation time and comes back to you with your last position. This is bad, the worst disadvantage of server authorized design. Player wants his character move left as soon as he presses left, you can't make him wait. Luckily client also have the same code as server, so why not execute it on client immediately and fix the final result with the answer from server? Thats what basicly input prediction is. Client presses left, the code in his side will move him to left, after some time lets say 200 ms, the real position comes from server and client corrects its position with it. If everything went allright, client won't notice anything, "step 2" will also help us with this.
Well, net has many tutorials and things about this subject. But there are 2 I really like:
Really good, covers dark spots: Valve-Source Engine Multiplayer Networking
Kind of history, fun to read and worth it: 1500 Archers on 28.8 ,
Answer: Pros:

this approach is more (most) piracy proof
you can apply updates more easily
centralized community

Cons:

huge bandwidth requirements
some users can hate that approach (privacy and stuff)
problems with local gameplay (LAN parties), singleplayer
Comment: The problems with LAN gameplay can be avoided by providing a dedicated server binary or allowing one of the clients to act as server. A solution that fixes both single player and LAN problems would be to transparently host a server on the client computer (if it's only a single player game, there shouldn't be any significant difference in computing power between this approach and a traditional binary).

This may not work for all game types
Answer: Server side logic also creates scalability problems - you have to do all the work for all the clients on your server - verses letting each client do his own share of the total work.
Comment: It's funny when I asked similar questions here in 2016, everyone just told me "never trust the client".
Comment: It depends on the game, but clients cheating themselves are not a serious concern, and clients cheating against other, honest, clients; whatever the server might have done to not trust the client, the honest clients can do instead.
Answer: Depends on what game you want to create and what part of the game.
If developing an RTS (or any game with a lockstepped model), then you definitely should only send the input and which simulation step the input was recieved.
If you want to do a shooter you could use both input and abstract functions. If you take Unreal Tournament 3 as the case, they created the multiplayer mainly via replicated function calls.
For movement they take the player input( compressed into a single bit for each action) delta rotation, acceleration & timestamp and send it to the server.
For other purposes like weapon they synchronize when you shoot (AFAIK, havn't looked into this part in depth yet).
For more static / less often changed values like health they send the variable to the client or server depending on what the programmer specified.
And for non-RTS games, remember client prediction.

Game logic on the server! Good or bad?


Why does dark energy produce positive space-time curvature?

Question: My understanding is that dark energy, or equivalently a positive cosmological constant, is accelerating the expansion of the universe and I have read that this gives empty space-time positive curvature, ie de Sitter geometry. I also understand that parallel geodesics converge when curvature is positive and diverge when it is negative. I would expect accelerating expansion of space to make parallel space-time geodesics diverge and thus make curvature negative. Is there a nice visual explanation why dark energy actually produces positive curvature?
Comment: Christoph's answer seems fine, but I would home in on what seems to be the fundamental conceptual error that led to the OP's confusion. GR describes curvature of spacetime, not just curvature of space. If you slice along an xt plane, then initially parallel lines will later diverge, and this is due to the cosmological constant. Spatial curvature would be a slice along a plane such as xy. In this type of plane, the current evidence is that the geometry is nearly Euclidean.
Comment: WMAP found that space appears to be "flat" and that there is no evidence of any positive curvature. IMHO a correct understanding of GR means this should be no surprise. See where Einstein described a gravitational field as space that was [neither homogeneous nor isotropic](http://einsteinpapers.press.princeton.edu/vol7-trans/192?highlightText=%22neither%20homogeneous%22) then look at the [FLRW metric](https://en.wikipedia.org/wiki/Friedmann%E2%80%93Lema%C3%AEtre%E2%80%93Robertson%E2%80%93Walker_metric#General_metric) which _"starts with the assumption of homogeneity and isotropy of space"_.
Answer: A positive cosmological constant leads to positive scalar curvature by definition. Just trace over the Einstein equation and you end up with
$$
R = 4\Lambda - 8\pi T
$$
which is just
$$
R = 4\Lambda > 0
$$
in vacuum.
The implicit, but more interesting questions are probably the following ones:
Why can we interpret the cosmological constant as dark energy?
Modelling matter as a fluid in equilibrium, ie
$$
T_{\mu\nu} = (\rho + p) u_\mu u_\nu + p g_{\mu\nu}
$$
the Einstein equation reads
$$
R_{\mu\nu} - \frac 12 R g_{\mu\nu} = 8\pi (\rho + p) u_\mu u_\nu + (8\pi p - \Lambda) g_{\mu\nu}
$$
Now, if we want to fold the $\Lambda$ term into the matter terms, we require
$$
\rho_\Lambda + p_\Lambda = 0
\\
8\pi p_\Lambda = -\Lambda
$$
which is
$$
\rho_\Lambda = -p_\Lambda = \frac\Lambda{8\pi}
$$
a positive energy density with negative pressure.
Take note that this pressure is not directly responsible for any acceleration or deceleration of the cosmological expansion: It is uniform across space and stays constant in time, and lacking a gradient, does not induce any forces. Its effect is purely gravitational in nature - after all, this is just the cosmological constant in disguise.
Does positive spacetime curvature actually lead to parallel geodesics converging?
Not necessarily due to the Lorentzian signature of the metric. Take 1+1 de Sitter space, which can be realized as a hyperboloid in Minkowski space and would look like this (picture taken from Wikimedia Commons):

We get geodesics from the intersections of planes through the origin of the ambient Minkowski space with the hyperboloid, and time-like ones from those which are angled less than 45° towards the time axis.
The vertical lines thus correspond to time-like geodesics and clearly do not converge.
This is where slicing into space-like hypersurfaces comes in: In FLRW cosmology, there's a preferred slicing where the galactic fluid is homogeneous. In de Sitter space, there's no matter and thus no preferred slicing, but we can nevertheless use it to illustrate various features of the cosmological standard model.
The horizontal circles, which we obtain by intersecting a parallel family of planes in the ambient space with the hyperboloid, correspond to a spatially closed universe. Choosing appropriate coordinates yields the metric
$$
ds^2 = -dt^2 + \alpha^2\cosh^2\left(\frac t\alpha\right)d\Omega^2
$$
where $d\Omega$ is the metric of the Euclidean sphere and $\alpha=\sqrt{3/\Lambda}$.
By tilting our planes, we can also create flat slicings with corresponding metric
$$
ds^2 = -dt^2 + e^{2t/\alpha}dy^2
$$
and open slicings with metric
$$
ds^2 = -dt^2 + \alpha^2\sinh^2\left(\frac t\alpha\right)dH^2
$$
where $dH$ is the metric of the Euclidean hyperbolic space.
While the light-like geodesics shown above - corresponding to particles at rest in case of the closed slicing - diverge, the spatial curvature will determine what happens to particles in parallel motion through space. However, this is not something that can be shown in our picture of a 1+1 spacetime.
How does this result in an accelerated expansion of the universe?
Looking at the spatial part of the metrics, all three slicings ultimately lead to an exponential expansion of space, which, in case of a de Sitter universe, is just a matter of geometry. In the closed case however, accelerated expansion happens only after a decelerating collapse to some minimal size determined by the value of the cosmological constant.
In Friedmann models, as long as the cosmological constant dominates over the matter content, we'll eventually approach de Sitter geometry and thus also exponential expansion.
Comment: Thanks, @Christoph, this is looking great! The second question is the one that was puzzling me. If I read your answer correctly, then the constant time circles on the hyperboloid are *not* geodesics since they are not formed by planes passing through the origin. Correct?
Comment: Also I am not famimilar with the equation $T_{\mu\nu} = (\rho + p) u_\mu u_\nu + p g_{\mu\nu}$. Could you define $\rho$, $p$ and $u$.
Comment: Actually $\rho$ and $p$ are clear from the later equations. Is $u$ the fluid velocity? I guess this is a tensor form of Bernoulli's equation.
Comment: @DanielMahler: your guess for $u$ is correct, and I added a link to the corresponding Wikipedia page; you're also right that the horizontal circles aren't geodesisc, but we can use them to model a closed universe that's contracting in the lower half and expanding in the upper one
Comment: Great. Thanks. One more bit of confusion is the minus sign in $\rho_\Lambda = -p_\Lambda = \frac\Lambda{8\pi}$. This is saying that accelarating expansion is caused by negative pressure, which seems counterintuitive.
Comment: @DanielMahler: I added a note about that; see also http://en.wikipedia.org/wiki/Dark_energy#Effect_of_dark_energy:_a_small_constant_negative_pressure_of_vacuum
Comment: @DanielMahler: I just added some missing pieces
Comment: Thanks @Christoph. This is a really great answer and an excellent resource for others in the future.
Answer: This is really a comment, but it got a bit long for the comment box. It's a comment because I kept meaning to go off and research this properly but have failed to find the time (and probably never will). So I'll post my initial thoughts, but treat this as suggestions for things to look at rather than a definitive answer.
When you say I also understand that parallel geodesics converge when curvature is positive I bet you have a mental image of a 2-sphere (apologies if I'm libelling you, but this is definitely my immediate mental image of positive curvature). The thing is that the 2-sphere is a Riemannian manifold i.e. the metric is positive definite. By contrast the manifolds we use in relativity are pseudo Riemannian i.e. the metric is not positive definite and indeed has the signature (-+++) or (+---) depending on your preferred convention. This matters because the scalar curvature is:
$$ R = g^{\alpha\beta} R_{\alpha\beta} $$
So the positive scalar curvature of de Sitter space doesn't mean it's like a sphere. It would if the metric is positive definite, but it isn't.
Comment: Yes, my main misunderstanding was that I was not aware that the relationship between scalar curvature & geodesics did not apply to indefinite metrics. I had once seen an explanation of curvature in terms geodesics in a book and thought it was meant to be universal.


Is it possible to simulate Mars gravity on Earth?

Question: Can you use an aircraft to simulate Mars gravity on Earth, similar to the way weightlessness is simulated by fling in a parabolic arc?
What would the flight profile have to look like to achieve mars gravity? I know the acceleration required to achieve weightlessness, 9.8 m/s2.
Comment: First: this SE is not, on the whole, about simulating reduced gravity in airplane flights, so it's really unclear from the way the question is worded what you're asking for. Second: you know Earth's gravity, Mars's gravity is easy to look up; all you have to do is subtract.
Answer: The short answer is "Yes, it's possible"
The typical technique to fly a zero-G parabola is to put the plane into a steep climb and when the airspeed is low enough, push forward on the yoke until the G-meter reads "0".
Mars gravity is roughly (3.71 / 9.8 = 0.38G).  Instead of pushing to 0, the pilot just pushes to 0.38.
This would result in a somewhat flatter arc and the experience would be a little bit longer than a comparable zero-G flight.
Source: personal experience.  I'm an aerobatic pilot and have flown similar profiles (but in a single seat plane, not a jet)
Comment: I've just asked [Could an aircraft ever simulate Martian gravity perpendicular to the aircraft's floor?](https://space.stackexchange.com/q/26731/12102)
Answer: Yes, and it is done in such parabolic flights as explained and showed in this video, (in French but with English closed-captions available) especially the cockpit scene between about 24:30 and 26:30 where you can watch the instruments and exterior view of the plane. Basically, you adjust the trajectory and speed of the aircraft to fit the required acceleration.
Comment: In theory, it is possible is the trajectory is carefully managed, but I don't see that 'lower gravity' anywhere in the video. Of course, when entering (and exiting) the parabolic trajectory, all the objects inside the plane are subjected to acceleration, and have 'extra weight' due to it. But during the phase of free fall, the apparent weight of those objects is zero...
Comment: @xxavier I may have blend memories from several videos including [this one](https://www.youtube.com/watch?v=xdJwG_9kF8s) as they were taken at the same time, buy I'm quite sure one of those explain they simulate several micro gravity settings (zero-G, moon gravity and marsian gravity)
Comment: @Manu H  It may be as you say, but it's not the case in the French video...
Comment: I've just asked [Could an aircraft ever simulate Martian gravity perpendicular to the aircraft's floor?](https://space.stackexchange.com/q/26731/12102)
Answer: Suppose at the start of the parabola the aircraft has
initial altitude $H$ meters,
speed $V_o$ m/s,
and is moving upward at an angle to the horizontal $M ^{\circ}$.
If the desired gravitational force is $G m/s^2$
then the aircraft must accelerate vertically at $(9.81-G) m/s^2$.
The horizontal component of the speed is constant at $V_x(t) = V_o\times \cos M$,
so that the horizontal co-ordinate after $t$ seconds is $X(t) = V_o\times \cos M\times t$.
Initially the vertical component of the speed is $V_y(t=0) = V_o\times\sin M$.
The vertical component of the speed is $V_y(t) =  V_o\times\sin M -(9.81-G)\times t$.
At the peak vertical speed is zero, and occurs at $t_{\text{max h}} = V_o\times\sin M/(9.81-G) $.
The vertical co-ordinate is $$Y(t) =  H + V_o\times\sin M\times t - {(9.81-G)\times(t^2)\over 2}$$
The maximum height attained is
$$Y(t_{\text{max h}}) = H+V_o\times\sin M\times[V_o\times\sin M/(9.81-G)] - (9.81-G)\times{[V_o\times\sin M/(9.81-G)]^2\over 2}$$
By symmetry it takes $t_{\text{max h}}$ seconds to go from the peak to the base altitude $H$.
Greatest altitude and time at reduced gravity occur if the initial angle is $90 ^{\circ}$, but steep angles introduce other problems. For a given initial airspeed and initial angle, a larger perceived gravity (as of Mars) has longer reduced gravity time than a smaller perceived gravity (Luna or freefall).
There must be sufficient airspace below the base height to accelerate and maneuver into the parabola, and recover from the parabola. At the peak there must be sufficient air density and indicated air speed for the control surfaces to function. The indicated air speed may be significantly less than the true air speed, and the pilot must compensate for winds that vary with altitude.
I am not sure that the perceived gravity will be perpendicular to the aircraft floor. For free fall that would not matter.
Example:
$$\begin{array}{lll}
  H                 & 6000 m      & \text{base height}                   \\
  V_o               & 200 m/s     & \text{initial speed}                 \\
  M                 & 30 ^{\circ} & \text{initial flight angle}          \\
                    & 3.71 m/s^2  & \text{desired perceived gravity}     \\
                    & 6.10 m/s^2  & \text{needed vertical acceleration}  \\
 X(t)               & 173 m/s     & \text{horizontal component of speed} \\
  t_{\text{max h}}  & 16.4 s      & \text{time to max height}            \\
Y(t_{\text{max h}}) & 6820 m      & \text{max height}
\end{array}$$
Comment: You raise a really good point about the direction of the gravity. Using a trajectory with constant ground speed (x) and a parabolic altitude profile (y) the simulated reduced gravity would continue to point to the center of the Earth, rather than be perpendicular to the floor. Trying to get the simulated gravity to be floor-normal makes the math problem much more interesting! And so I've just asked [Could an aircraft ever simulate Martian gravity perpendicular to the aircraft's floor?](https://space.stackexchange.com/q/26731/12102)
Comment: In comments [here](https://space.stackexchange.com/q/26731/12102) there is interest in you undeleting [your answer](https://space.stackexchange.com/a/26742/12102). Two votes so far. Seeing as how other answers are branching out and being well-received, I think yours would be a great addition. Consider undeleting?


How can I make a video more seekable?

Question: I am looking at the factor that allows software video players to seek at any (or close to) position in the video.
Is this the keyframes or what?
Answer: The problems with seeking are typically in the video player and not in the videos themselves, so you may want to look at different video player. A video player should be able to seek to any frame in the video, regardless of format and the encoder settings used. It is also technically possible to play any video backwards, even though very few players support this.
The problem is, seeking into frames that are not keyframes is difficult and CPU intensive. Frames that are encoded as keyframes can be decoded on their own, while non-keyframes depend on other frames to be decoded. If you are playing the movie left to right all the dependencies  for a given frame have been already decoded, but if you are seeking directly into the frame, then the player needs to search for all those dependencies, decode them and only then it can decode the target frame.
So I think I can summarize my advice as two different suggestions:

Switch to a player that can seek to any frame.
if you can't switch to a better player, then encoding your video with more frequent keyframes will give you better seek accuracy, at the expense of picture quality (if you keep the bitrate the same) or file size (if you increase the bitrate to compensate).

Good luck.
Answer: Yes, that has to do with keyframes.  Most players can only seek to a keyframe.  Others will go to the prior keyframe and decode up to the point selected.  Others will just play gibberish until the next keyframe.  Having regular keyframes increases your file size, but also adds many more points a user can seek to in your video.
If you are referring to how to make your video more seekable for the web, that is a different problem.  Video compression is typically not a constant bitrate which is why it is hard for a web-based player to guess the byte offset of a particular position in the video.  Many web players allow sending a file of metadata that contains offsets to help with this problem.

How can I make a video more seekable?


Usage of the word "senior"

Question: I was talking to a person from another company on the phone on the other day.
He asked me something that I could not answer, so I said, "let me go talk to my senior about the issue." Although she seemed to understand what I meant, I was wondering if this usage of the word "senior" is correct instead of using "supervisor" or "boss."
Comment: Where was this person located? I have heard this use of *senior* from South Asians, perhaps using a translation from usage in their mother tongue, but it is not used by native speakers in this way in Britain, North America, or the antipodes so far as I know.
Answer:
I was wondering if this usage of the word "senior" is correct instead of using "supervisor" or "boss.

No, unless you're being very broad with the definition of a "supervisor".
I think the word you were actually looking for is superior. This is a valid synonym for someone who is above you in the hierarchy.
Note that the antonym, inferior, is technically correct but you shouldn't use it. It is considered disrespectful because it implies that you are putting the other person down or calling them incompetent.
As per T.J.L.'s comment, "subordinate" is a contextual antonym of superior, which is more acceptable to use. However, I would still suggest that you refer to your subordinates as colleagues as a matter of politeness and respect, to avoid inferences about you stressing their lower place in the hierarchy.

Contrary to the other answers, I do think there is a valid use case for "senior", but it is not in reference to a superior.
Senior does not denote someone who is above you in the chain of hierarchy; but rather an equal who is more experienced than you.
The antonym, for someone who is less experience than you, is junior. Medior (= of average experience) is only rarely used and more often omitted.
A senior developer is not a developer's boss. He is simply a more experienced colleague of the developer. They are on the same hierarchical level.
As a simple example, I've worked at the company for 4 years, and Tim has worked at the company for 8. We are both developers, but he is more experienced than me. To me, Tim is a senior developer. To Tim, I am a junior developer.
A colleague of yours isn't particularly assigned to you, it would be more correct to say "a/the senior [colleague]" instead of "my senior [colleague]".
However, it's possible that your company has rules that effectively give senior colleagues some limited authority over their junior colleagues.

My current company does in fact assign senior developers to junior developers, with the intent of coaching. However, I still wouldn't use "my senior", since the person you're talking to likely isn't aware and doesn't need to know that you have a coach. However, it would be correct to call your coach your supervisor. In this case, senior is indeed synonymous with supervisor.
Other companies may defer to the judgment of senior colleagues. E.g. if a senior developer disagrees with a junior developer, the company follows the senior's opinion. This can lead to a work environment where senior colleagues are effectively seen as a "mini boss" by the junior colleagues. In that sense, one could consider a senior to be higher up in the hierarchy.

But these examples are context-specific. As for the phone call you were having, you would've been better off referring to your boss as your superior.
Comment: In context, the antonym of "superior" is "subordinate" not "inferior".
Comment: I'll add that "Senior Manager" is an official title at some businesses, and it does represent a superior/subordinate relationship. (Senior Managers are in charge of the junior managers.) In such an environment, it's possible that "let me talk to my senior" by a junior manager is an ellipsis for "let me talk to the Senior Manager who is in charge of my department".
Comment: @R.M.: There are indeed fringe cases where it's correct, like the one you referenced. But it would still be unclear for the person who you're talking to (unless they are aware of the company hierarchy and titles). Part of communicating clearly is communicating in a way that the recipient understands your meaning, and "my senior" isn't all that clear without the recipient knowing the proper context.
Comment: Another alternative to "inferior" is "report".
Comment: _"A senior developer is not a developer's boss. He is simply a more experienced colleague of the developer. They are on the same hierarchical level."_ While I agree that this is sometimes true, it is not always true. It depends on the organisation. When I was first made a senior dev, although I did not become their bosses in pastoral terms (I was not their _manager_), I had a level of formal technical superiority and oversight/approval privileges on their technical output. We were not equals on the company's organisational chart. I don't _believe_ this is unusual, though I could be wrong.
Answer: It is not the common usage. The word senior can be used as a noun, but then it normally means "Old person", or (in American use) "Final year student". In the context you give, "senior" would be understood, but there are better alternatives.
To mean a person above you in the company you can use "supervisor" "line manager" or "boss". You can use senior as an adjective "a senior colleague".
You should also be aware that there are cultural differences between English speaking cultures and many others in the attitude to hierarchy.
Answer: Yes but this is not a fairly common term to use. I've heard it used by phone support. "Let me talk to my senior." But more commonly: "Let me talk to my senior supervisor." For some reason I most often hear senior and supervisor combined. Certainly boss and supervisor are two other ways that are perfectly acceptable in conversation.
Comment: I agree. I would take it to mean that "senior" is a specific part of the person's title, differentiating it from the speaker's own title. As in, I'm a Junior Shipping Clerk, and Bob's a Senior Shipping Clerk, and for stuff over 100 lbs I have to get "my Senior" to approve it. Within such a strict context I can imagine that this idiom could be the norm.
Answer: It is acceptable to use senior in this context- see meaning 2 in the Oxford Dictionary definition- but it is not common. This NGram shows that boss is considerably more widely used.
Answer: In such call, if I needed to talk to my peer who has more knowledge about technology (and not a boss/supervisor), without involving the caller into hierarchies, I might just say "let me talk to our local expert (on X)".

Usage of the word "senior"


backup and migrate Cannot delete or update a parent row: a foreign key constraint fails

Question: I have tried to use backup and migrate from an existing system into a fresh Bitnami Drupal 7.4.1 Civicrm 4.6.9 install on another machine. Win10
BandM 7.x-3.1
I received the following error:
PDOException: SQLSTATE[23000]: Integrity constraint violation: 1217 Cannot delete or update a parent row: a foreign key constraint fails in backup_migrate_source_db_mysql->_restore_db_from_file() (line 199 of C:\Bitnami\civicrm-4.6.9-1\apps\civicrm\htdocs\sites\all\modules\backup_migrate\includes\sources.db.mysql.inc)
I looked at the existing answers and am unable to get it to work.
Please help.
Answer: Backup and Migrate module may not be compatible with CiviCRM, and may not understand how to handle the many foreign key constraints within CiviCRM.
Here is the easy way:

Drop the database entirely (back it up first please)
recreate that database with the same name
then restore from your backup.

Here is the hard way:
Particularly, if a failed update has altered the table structure of your database, simply restoring may not work with any tool, because the schema has changed. More information:
http://wiki.civicrm.org/confluence/display/CRMDOC/Ensuring+Schema+Integrity+on+Upgrades
Comment: Thank you. That was easy, the BAM module had me consumed for hours. This was a few minutes. Thanks so much. My version of PHPMyadmin had an import feature which made it very easy.


Are there any sites that let me book 7 or more multi-city flights?

Question: I have a project that is requiring me to travel to seven different locations and I need to find a travel site that will allow me to book more than six multi-flights in order to accommodate for this need. does anyone know of any sites that will allow me to do this?
Comment: Why not split this in 2x4 legs?
Comment: what about a round-the-world ticket? It might not be the best fit for your specific case (there usually are some conditions like always go eastwards) but it's worth trying: http://travel.stackexchange.com/questions/26/what-should-i-know-about-around-the-world-flights
Comment: I don't know any systems that support such an extensive multi-location flight. I've experience that sometimes it's already a lot more difficult to book a flight consisting of four legs than to book 2x2 legs individually. Is there a reason you cannot split your six stops?
Answer: The only time I have done 19 stops is with a traditional travel agent but you can do this with Air Treks and they do have really good multi-city prices. It took several days to get it all but the agents did most of the work and I got a folder with 39 boarding passes several weeks later.
Traditional sites like Expedia, Travelocity, etc are extremely expensive for multi-city routes, at least every single time I tried! They even have a shorter limit which may be fewer than 7 stops.
Now you did not say where you are going - which is great to keep the question general - but you may try some variants if you visiting both cities which are close together and some that are far.
For example, you can get a price for a route that goes through major cities and then take short round-trip domestic flights on local airlines to reach the smaller cities. Otherwise you may end up with excessive costs or really strange itineraries like getting a stop over in China between two cities in the Philipines which happened to me!
Another option to save costs is to build your trip out of enclosed round trips. For example if you want to go A -> B -> C -> A, you can A -> B -> C -> B -> A by booking A <-> B and B <-> C as two round trips. I saved over $1K like this once.
Comment: How do you get 39 boarding passes for 19 flights?
Comment: There were 19 stops on my itinerary. The other 20 passes were for connections, all but one segment passed through a single hub city (Hong Kong mostly - got to know the airport quite well!) and the last segment had two stops.
Answer: Kiwi supports 8 segments in multi city flight search

AirWander supports upto 16 segments in multi city flight search

see: https://travel.stackexchange.com/a/152708/40874 for more detail


How to spin up 1541 drive without C64

Question: I have a 1541 drive and I want to make it spin but I don't have a Commodore computer. I don't need to read data, I would just like the drive to spin. Can I manually tell it to spin using a raspberry pi or something?
Comment: There are various ways for modern-ish computers to emulate the IEC bus, google for "X1541 cable".
Answer: One way to do this is to program a Raspberry Pi to simulate an IEC bus controller, then drive the 1541 that way, via the 6-pin IEC port on the drive.  This is very similar to using a PC parallel port with a specially wired parallel-to-IEC cable, just using a Raspberry Pi instead of a PC, and using some general purpose I/O pins rather than the parallel port.  Once that's done you can save files, load files, format disks, or whatever, just by sending the appropriate commands down the IEC bus.
If you're willing to open up the drive and tinker with the internals you could probably drive the 'motor on' line directly.
Comment: The [raspbiec](https://github.com/Flogistoni/raspbiec) project on GitHub looks promising.
Comment: Another promising project is Pi1541 at https://cbm-pi1541.firebaseapp.com/  I can't wait to put this together and give it a try.  Source code is available at: https://github.com/pi1541/Pi1541
Comment: I wondered whether there's actually a timeout in the C1541 for IEC communications. If not then it feels like you could just wire up a couple of switches and tap out a few commands for yourself, given that the data clock is explicit?
Comment: What would I have to do to "drive the 'motor on' line directly"? Thanks.
Answer: The procedure to enable the spindle motor of a disassembled 1541 drive is given in the Service Manual for the drive. This is the procedure you would use to calibrate the motor speed.

_MTR output from the PLA is active "low". This signal is passed, through the current driver UD2, to the motor control PCB. When _MTR is "low," Q1 is biased off, and Q2, Q3, and Q4 are biased on, allowing current flow through the spindle motor coil. Attached to the shaft of the spindle motor is an inductive tachometer that generates low level AC voltages, as the motor spins. The output of the tachometer is rectified by CR1-CR4. IC 1 monitors the output of the rectifier and adjusts the bias to Q2, which changes the bias on Q3 and Q4 to regulate motor current for a constant velocity. VR1 is a manual speed adjustment. The speed can be adjusted by watching the 60Hz strobe as the adjustment is made or loading the system test from the diagnostic disc.
  The Newtronics Motor Speed PCB is electronically the same as the ALPS Motor Speed PCB, but some of the discrete components have been integrated.

And here is the link to the 1541 Service Manual. Just search the document for "_MTR".
Comment: Perhaps I'm missing something, but all I get out of this is that if I adjust VR1, I adjust the speed of the disk drive motor. I guess, that if _MTR is "low", the drive will spin? But how does one manually drive _MTR low?
Answer: Since the main drive runs for a short moment on reset (POST), the easiest method to keep it spinning is to pull down /RESET on the serial port (pin 6, middle to pin 2 (GND), at 4 o'clock position).
You can simply use a serial-port reset button intended for the C64.

How to spin up 1541 drive without C64


Brexit deal and the EU national governments

Question: Once the Brexit deal has finished going through the UK parliament, does it still have to be ratified by the national government of each EU member or has it already got past that stage?
Comment: My understanding is that it still has to go through all 27 parliaments and some regional legislatures too. It is a very good point which you raise. And in that context the potential *cause célèbre* between the UK and Cyprus (which involves, by extension, Israel), takes on a new importance.
Comment: @WS2: you're talking about the "future relationship" (as an actual treaty, not a mere "political declaration") which is a different thing. https://www.euronews.com/2019/11/01/brexit-draft-deal-first-of-many-hurdles-to-a-smooth-exit
Answer: Under Article 50(2), once the European Parliament has approved the withdrawal agreement, the European Council (i.e. heads of government) will vote to approve it.  None of these votes has yet happened.
There is no need in EU law for the agreement to be ratified in individual parliaments.  Only a qualified majority of EU states (15 states representing 65% of the population) voting for it at an EU summit is required for the withdrawal agreement to be approved by national governments.
Comment: The exact requirements will depend on the laws in each individual country.  I believe they all require at least a vote in their national parliament, while some will have additional requirements on top of this (eg. Belgian law will also require the consent of regional parliaments).  But this applies to the future trade deal (if one is reached), not to the withdrawal agreement.
Comment: But presumably any eventual trade agreement requires parliamentary support in all countries?
Comment: The Council thresholds you mention only apply if the deal (or any proposal) also has the approval of the Commision, which in this case it does... (The Council threshold is higher [72% % of the members and representing 65% of the population] otherwise.)
Comment: @WS2, the requirements for the eventual agreement depend on the scope of that agreement. Trade matters are up to the EU, many others are up to the individual nations.


Power supply turn off when connected to sata HD

Question: Hi I bought WD Essentials 1TB and it worked fine until I used wrong power supply (from netbook) and it stopped working. I opened the black case and found WD Cavier Green SATA drive. I took it out and bought IOMAX usb connecter for sata and pata.
I tested first with PATA drive and it worked fine but when I connected WD Cavier drive (taken out from WD essentials) the power supply just turn itself off for no reason. can someone help?
Answer: It sounds like you damaged the the hard drive by using the wrong power supply.
All I can suggest is either testing another SATA drive in your new dock and if it behaves how you would expect, then it sounds like the drive has gone faulty.


Are edits for just filling in image descriptions accepted?

Question: I'm a somewhat new user on this site and I was wondering, I've come across many posts that have an image within them but with no image description or it still includes the default message of, "enter image description here". I do not yet have enough reputation where my edits are instant and have to go under peer review. If I were to edit these posts only filling in a description of the image and change nothing else, would that be substantially enough to get accepted under the peer review?
Comment: Personally, I would reject an edit, if the only thing it did was provide an image description.  You can be banned from suggesting edits if enough edits are rejected.
Answer: Not really. if they are alongside other reasonably substancial edits, go ahead. Editing to fix something 90% of our users will never see seems pointless.
One exception might be if the question would be of interest to someone who uses a screen reader, in which case, go ahead. Just make sure you mention that in the edit summary.
I'd also keep in mind that seeking these out, and the resulting flood page edits might make people irate, new user or not.


How exactly are correlated defaults used/analyzed?

Question: I've read a lot about correlate defaults but I can't seem to understand how they're used practically in a portfolio theory setting. Suppose I have two (?) companies, X and Y, and historic default information for each. How does knowing the correlation of defaults between X and Y help me with constructing my portfolio/loss curves? And how does this change if I have a basket of securities instead? I can add more details if needed.
Comment: what does mean "constructing my portfolio/loss curves" ?
Answer: The correlation does not play any role for a linear portfolio, such as a CDS index, However, for a portfolio with nonlinear dependence on the loss of  underlying entities, such as the case for a CDO or an $m$-th to default swap, the correlation plays a role. Here, certain techniques such as copula may be needed, depending on the complexity of the structure.
Answer: The way to model the correlation may depend on the portfolio you have.
For example you may model the default distribution for a small portfolio of loans using a mixed binomial model. In this case the state of the economy determine the probability of default, but in each scenario the individual defaults events share the same probability (homogeneity). Thus, we have correlation in default events through common dependence on a factor. This is obtained by making the mixture parameter stochastic: p (the probability of default) is randomized. Let $p ̃ $ be the stochastic default probability, which we assume, has a distribution on [0, 1] which can be continuous (i.e., given by a density f) or discrete. Conditional on the value of  $p ̃ $ the number of defaults follows a binomial distribution with probability parameter $p ̃ $.
For example, in the discrete case, with two possible scenarios, the probability that k out of N default is given by:
$P(D=k)=f(p_1)\binom Nk p_1^k (1-p_1 )^{N-k}+f(p_2)\binom Nk p_2^k(1-p_1)^{N-k}$
The variance of the number of defaults is:
$Var[D]=Np ̅(1-p ̅ )+N(N-1)Var[p ̃]$
The first term is the variance that would apply if the default probability were fixed (i.e. without correlation). The second term is additional variance. Variation in $p ̃ $ is an important contributor to the variance in the number of defaults because it determines the correlation between defaults events. Let $X_i$ denote the default indicator of issuer i (equal to 1 if i defaults and 0 otherwise), we have:
$ρ(X_i  ,X_j )=\frac{Var[p ̃ ]}{p ̅(1-p ̅)} ,   i≠j$
Note that, since the variance in $p ̃ $ determines the correlation between default event indicators, we can model the correlation by properly chose the distribution of $p ̃ $.
It can be proved that for homogeneous large portfolios of loans the distribution of the loss function is equal to the distribution of $p ̃ $. Merton model has an economic meaning and fit whit in this framework so it is often used for this purpose. Assume all firms have the same correlation $ρ$ and same default probability $p ̅ $. The "Fraction of defaults" cumulative distribution for a Large homogeneous loan portfolio may then be written as:
$P[p(M)≤θ] = N(\frac{1}{\sqrt{ρ}} (N^{-1} (θ) \sqrt{(1-ρ)}-N^{-1} (p ̅ )))   $
This is also known known as one-factor Gaussian copula model and has many applications with CDO.


Is there modal logic without possible worlds?

Question: Would it be desirable to carry out a deflationary research programme in modal logic? In other words, would it be desirable to re-think modal logic without the possible worlds semantics? The original hierarchy of modal logics was originally based on Lewis's axioms (1914) interpreted by Kripke in terms of possible worlds in 1950s. But that seems rather technical and removed from intuition. Is it avoidable?
Comment: First welcome to Phil.SE! Secondly, it's probably useful to explain, or at least link to what you mean by Lewis's axioms, and how you imagine a 'deflationary research programme' would work here - otherwise you're leaving to the community to work out quite what you mean by them; by putting in some *effort* explaining, you're more likely to get a better quality answer.
Comment: @conifold: ahem, is this another one of your binges?
Answer: Yes, there is, and for a number of reasons it is also desirable to rethink modal logic without the possible world semantics altogether, including Kripke's models. Forster in Modal Aether gives a detailed analysis of presuppositions behind it and shows that most of them are not satisfied in the "possible world talk" by philosophers:

"I can well imagine that many philosophers reading this will irritably exclaim that these assumptions are distorting oversimplifications which they do not make when applying possible world semantics to their concerns... the point is being conceded that possible world semantics are not applicable to their concerns".

Girard in Transcendental Syntax writes that "what people do with Kripke models and similar constructions [is] they take the language as it is, call it reality, and state a completeness theorem". Kahle in Modalities Without Worlds lists other philosophical and technical criticisms:

"The ontology explodes. Next to the actual world, one needs additional possible worlds to interpret modalities... If we do not consider nested operators, modal logic does not provide more than a box in front of the derivable formulas. Thus, the power of modal logic is located
  only in the nesting of operators... In fact, also outside of logic, we are not aware of any practical examples where modal logic or possible worlds semantics helps us to determine a necessary truth, which was not already (explicitly or implicitly) built in by certain axioms or constraints on the variety of worlds".

Kahle traces the problem to Lewis's axioms, especially S4, and his modal realism that embraces "exploding ontology" in semantics. He then discusses proof theoretic alternatives to possible world semantics. Possibility is defined as independence from a specified set of assumptions, and the usual definition of necessity as negation of possibility is discarded. Unconditional necessity  in natural languages hardly occurs at all, and most uses are of the form "p is necessary for q", e.g. "team must win today to win the league", this leads to an alternative treatment of necessity. He also suggests that, as in natural languages, applicability of axioms should be context dependent. For another approach see Divers's Possible-Worlds Semantics Without Possible Worlds and Fine's Counterfactuals without Possible Worlds.
Answer: In short, yes it is. In fact, it may be desirable to re-think Lewis' entire approach. His objections to Lukasiewicz' approach to modal logic (as discussed in Lewis & Langford "Symbolic logic" ( p. 213-234) are not insuperable.
Answer: One can always topologise:

As McKinsey and Tarski showed, the Stone representation theorem for Boolean algebras extends to algebras with operators to give topological semantics for (classical) propositional modal logic, in which the "necessity" operation is modeled by taking the interior of an arbitrary subset of a topological space. In this article, the topological interpretation is extended in a natural way to arbitrary theories of full first-order logic. The resulting system of S4 first-order modal logic is complete with respect to such topological semantics.

AWODEY, S., & KISHIDA, K. (2008). TOPOLOGY AND MODALITY: THE TOPOLOGICAL INTERPRETATION OF FIRST-ORDER MODAL LOGIC. The Review of Symbolic Logic, 1(2), 146-166. doi:10.1017/S1755020308080143

We present the main ideas behind a number of logical systems for reasoning about points and sets that incorporate knowledge-theoretic ideas, and also the main results about them. Some of our discussions will be about applications of modal ideas to topology, and some will be on applications of topological ideas in modal logic, especially in epistemic logic. [...]
In the area of applications of topological ideas in epistemic logic, we include a section on the following topics: a topological semantics and completeness proof for the logic of belief KD45.

Parikh R., Moss L., Steinsvold C. (2007) Topology and Epistemic Logic. In: Aiello M., Pratt-Hartmann I., Van Benthem J. (eds) Handbook of Spatial Logics. Springer, Dordrecht

This paper presents a survey of topological spatial logics, taking as its point of departure the interpretation of the modal logic S4 due to McKinsey and Tarski. We consider the effect of extending this logic with the means to represent topological connectedness, focusing principally on the issue of computational complexity. In particular, we draw attention to the special problems which arise when the logics are interpreted not over arbitrary topological spaces, but over (low-dimensional) Euclidean spaces.

Kontchakov, R., Pratt-Hartmann, I., Wolter, F., & Zakharyaschev, M. (2008). Topology, connectedness, and modal logic. Advances in Modal Logic, 7, 151-176.


On-top-of-fridge storage

Question: Is there any concerns (food safety, quality, otherwise etc) with storing dry goods [spices, protein powder], or bottles [wine bottles, pop cans] on top of a refrigerator unit?
Answer: The top of your fridge might tend to be a relatively warm spot in your kitchen: it's up high, and the fridge itself gives off some heat. Exactly how warm would depend on your kitchen and your fridge.
So it might not be the best spot for spices, since heat can make them age and lose flavor more quickly. Some other foods also prefer relatively cool storage.
Otherwise it should be totally fine; most things can handle being slightly warmer than the rest of the kitchen.
Answer: No. There are no issues with using the top of your fridge as you would a pantry.
Answer: I do it all the time. Wine bottles (for short storage, usually until the weekend ;), Bags of chips, some bread, etc.
Your fridge doesn't output any fumes or chemicals (it's a closed-loop system). Other than light getting to your items (which may shorten the "shelf-life for some items), there's no risk or hazard.

On-top-of-fridge storage


Can a Yongnuo YN-560 III wireless flash be used with a Hahnel Combi TF (both for Nikon)?

Question: Can a Yongnuo YN-560 III wireless flash speedlite for a Nikon DSLR be used with a Hahnel Combi TF for Nikon?
Comment: Possible duplicate of [Are RF wireless triggers systems compatible with one another?](https://photo.stackexchange.com/questions/40335/are-rf-wireless-triggers-systems-compatible-with-one-another) See also: [How compatible are different flash brands for remote control over the flash?](https://photo.stackexchange.com/questions/85241)
Comment: What are you wanting to control remotely? The flash from the camera, or the camera from the flash?
Comment: Those possible duplicates assume the OP wants to trigger an off camera flash while physically operating the camera. That assumption is far from clear in the question, particularly since the Hahnel TF is marketed primarily as a way to remotely fire the camera without physically holding it.
Answer: For triggering the flash remotely from the camera:
Only if you also have a Hahnel TF receiver attached to the hot foot of the YN560 III as well as a Hahnel TF transmitter attached to the camera's hot shoe. You'll only be able to tell the flash to fire. You will need to set the flash power and zoom head using the flash's own control panel.
The built-in radio receiver in the YN560 III is not compatible with the Hahnel TF radio protocol, and the Hahnel TF system is not compatible with the YN560/RF605/RF603 radio protocol.
If you want to use the built in radio receiver of the YN560 III, or if you want to control flash power and zoom of the remote flash from the camera, you need a transmitter that uses the YN560/RF605/RF603 protocol, such as the YN560-TX.
For triggering the camera remotely with the flash attached to the camera's hot shoe:
It will work, you just won't be able to place the receiver on the camera's hot shoe. The actual signal is communicated via a cable that plugs into the remote shutter release port. Some folks use velcro to attach such accessories to a camera body without tying up the hot shoe when communication via the hot shoe is not needed.


How do MLB Managers do the lineup card on Jackie Robinson Day?

Question: How are lineup cards and official scorebooks recorded on Jackie Robinson Day? Do the managers/scorekeepers use the players' regular numbers, or is it literally "42" for every player's number?
Answer: According to multiple sources I've seen, they don't even put jersey numbers on the lineup card, so I don't believe they put anything even on Jackie Robinson day.  Here is a picture of a game used card used in the Cubs vs Reds game last season during Jackie Robinson day, and no numbers are present.  The only information present is Batting Order position, Name, and Position number.
Comment: Ah very good, thank you. How about for scorebooks? Every scorebook I am finding shows player numbers - cannot find an official one for April 15, though.


WinOnX how to install DirectX

Question: I want to play a cool game called Just Cause 2. I have a copy, but there is a problem because it needs DirectX 11. Anybody knows how I can install that DirectX? Because I think it's only for Windows, but I don't know WinOnX is emulating Windows 7.
Answer: WinOnX is a repackaging of the Wine framework. Wine does not emulate Windows (strictly speaking), it just provides adapter libraries to allow Windows programs to run. According to this page, Just Cause 2's compatibility with Wine is rated "garbage" and it doesn't run. There is also a link to this page that shows the progress of re-creating the DirectX DLLs for Wine. As of early June 2012, they seem to be about 37% complete with DirectX versions 8-10, and there's no indication of work on DirectX 11 yet.
tl;dr: It won't work. You need to virtualize a real copy of Windows using VMware or Parallels or run Windows in Boot Camp to play a DirectX game like that on your Mac.

WinOnX how to install DirectX


Are DUPLO blocks compatible with LEGO blocks in any way?

Question: Can I build a model out of both DUPLO blocks and LEGO blocks? Do they fit together?
Answer: Yes! You can add LEGO on top of DUPLO, and DUPLO on top of LEGO. Here's an example picture from The Brick Blogger:

Because stacking LEGO on top of DUPLO requires the particular LEGO tube design on the bottom (to fit in the hollow top of the DUPLO bricks), many "LEGO-compatible" bricks do not share this compatibility with DUPLO - at best, you can stack DUPLO on top of them, but not the other way around.
In addition, you can use only some types of LEGO bricks with DUPLO. Plates, tiles and other modified pieces can't stack with DUPLO. DUPLO can sit happily on top of plates, but plates and tiles only balance on top of Duplo, there's no real clutch between them that way.
Comment: JANGBRiCKS has a nice video explaining this: http://youtu.be/abdZ2pSnde0
Answer: Some elements are compatible, others are not. IIRC

You can stack regular 2x2, 2x4 etc lego bricks on top of normal duplo studs and they fit and hold fine.
You can't cover only part of a stud, so bricks with odd dimensions can't stack completely on top of duplo and 1xn parts can't stack on top of duplo at all.
Bricks with curved edges are similarly going to be incompatible.
Thin plates don't have enough depth to take up the taller Duplo stud.
You can stack Duplo bricks on Lego studs but only the outside of the brick grips the studs which in my experience leads to a relatively weak connection.
Duplo base plates have studs with flat tops. These are incompatible with Lego.

It seems that the basic Duplo-compatible Lego bricks are a lot less common than they used to be. I just looked at a "Large Creative Brick Box" and found that only about 16% of the contents was traditional Duplo-compatible bricks. Themed sets (including the "Juniors" range ) often contain hardly any.
Answer: Duplo bricks manufactured post 2002 are also compatible with a larger brick, produced for a limited time, called Quatro- it is 4 times the size of standard system bricks in every dimension. Older 2x4 bricks were limited by the height of struts between the tubes.
Answer: Yes! Duplos are 8x the volume of the corresponding Lego bricks.
Comment: You are correct, but that fact does not prove that they fit together. As **@Joe Wreschnig** say in [his answer](http://bricks.stackexchange.com/a/46/171), many "LEGO-compatible" bricks are not compatible with DUPLO, although they have the same volume (and "outer shape") as a LEGO brick.
Answer: The answer is: Yes. In fact in my annual project I use a Duplo part that a friend got me from one of the Lego Land parks. Never had a problem using it.
Answer: Yes, the even by even sized bricks fit to the Duplo studs, can't overhang. Lego plates on top leave a gap. Could overhang from that and add bricks under it, but why bother as it costs more (A 2×2 Duplo brick costs 50p, a 2×4 LEGO System brick costs 19p). Any Lego fits under, but only some Duplo hold with fancy tubes then still not at the corners.
The Duplo brick's walls have the same thickness as older normal Lego, with ribs.In fact older 2×3 without cross support fit if over hanging, so this just leaving 3 normal Lego studs on the corners not over hanging. A 2:3 slope 3×3 fits when over hanging corner, so could build a roof with eaves.


Should I discard rough sketches as I develop my final version?

Question: I have a series of paper sketches done as part of my design process. As I take the design to the next stage I am creating a better representation of my design that builds on my sketches and will eventually lead to my final design. Do you discard rough product sketches? Some of my sketches are very rough and I feel as if it might help me to discard those I didn't take forward in order to hone my final design. At the same time I would like to keep at least an example of my thought process in a coherent / well presented way.
Comment: At my college / uni it was part of our practice to retain all dev work in a journal including any roughs and notes, even if on a cig packet. Initially of course this was to track the thought process rather than relying on a final piece (only) submission. However, recording is viewed as a useful tool for memory and potentially an inspiration for future briefs. You wont necessarily show these to a client, but it is useful for mentoring/tutoring and presentation to students. At some stage you should look to do this also - gives you a personal review / pit stop opportunity for your practice.
Answer: Never discard sketches. They may contain ideas and inspiration for other projects or even later versions of the same project. At the very least, you can reflect on them later and be inspired for new work.
They can also serve to illustrate a point when presenting your work. For example, if a certain shape or other decision seems a very obvious obvious choice that the client will probably expect you to make, it may serve you well to show your sketches of that idea and use them to show why you didn't go through with that line of thought.
I use a journal to sketch in, and even doodle and make small notes. I've gotten so used to having a repository of old ideas and doodles around, that I feel lost without it when starting a new project. When I've been doodling on a loose piece of paper, it even pains me to throw it into the bin!
Comment: Yesterday's crap can be tomorrow's gold. I'd rather keep too much than too little.
Comment: Good answer, but  I recommend keeping good order of all this stuff and some of it will be crap and not worth archiving.
Comment: Next question would be - how often do you revisit stuff and how much of it is visible in your workspace?
Comment: @AndrewWelch You're asking pretty precise questions about a process that is at least part art. I'd love to discuss this with you in [chat] at an opportune time, but I'm afraid I won't be able to give cold hard numbers.
Answer: I just bumped on this thread while i was working on a project and i thought it was worth answering to your question.
It's a real coincidence because in the contest i've just joined, the Contest Holder is specifically asking to show the work in progress from sketch to digital. I will not only keep the sketches, but add screenshots of my work in progress too.
IN my practice i do this not just to show that the work it's mine and original, but because i want to show the potential client the process my artwork creation.
1) The client get a better understanding of the work process and the amount of work i put in my job (sometimes underestimated from clients).
2) I think this part of the process can help both client / designer in case of changes are needed as the client has a better vision of the whole work so that the changes can be done quicker and more efficiently.
3) I agree with Vincent post. I myself get a lot of inspiration from old sketches i used for other projects. Sometimes i take 1 or more elements of a particular sketch or i redraw the same sketch again and in the process a new illustration come up.
4) I keep everything rough and better sketches. I leave my sketches close to my desk on top of a shelf and easy to access. This is important because it's quick to review them. If i don't use this system it would be too annoying and wasting time to look for all the doodles around the house and i'll end up never looking at my old works.
The only downside of this process is that my studio has paper flying every where! So once in a while you have to tide up because your work environment can become very messy... you'll drawn in paper!!!
This is my 2 cents. I hope it helps.
Comment: Sketches aren't for clients. And any 'contest' sponsor asking for them seems a little suspect. It's fine to show clients sketches, but, in general, you don't always want your clients seeing how the sausage is made. The sketches are also your own proprietary work. Strategically it may not always be something you want to expose to your clients.
Comment: seems sensible to be but I agree with @DA01 that it isn't always a good idea as clients might not be bothered about seeing that stuff. And to be honest, that is most likely to be the case.
Comment: I have been doing Contests for a long time and i never had a problem with any Contest Holder. They are Guaranteed so that the designers are safely paid. There's nothing suspicious if a Contest Holder / Client asks to see sketches. I disagree about not showing the process of "how i make my own artwork".  i think that not showing is the "old concept" of doing design. Clients nowadays have much more knowledge then the past some of mine are graphic designers that employe me for an illustration job.
Comment: Sometime they are interested to know the details and i don't have any problem to share with them my sketches. The more clients can learn the more "we" the designers community can benefits too in the future when we relate with a client. This is my opinion, but understand your concern of showing your work we are just different. Anyway i'm happy i triggered a little debate about this issue, difference help to grow the community, cheers!


Could vortex generators be used to preserve aileron authority during a stall?

Question: I know that using aileron input in the approach to a stall is generally inadvisable; what if vortex generators are placed at the wingtip (where the ailerons sit), meaning that the ailerons will still have roll control authority available even when the rest of the wing is stalled? In this case, would aileron input be permissible?
Comment: This question and answer will depend greatly on aircraft—especially wing—design. For example, certain common trainers can be quite stable in a wing stall, with substantial aileron and rudder control. VGs may be one way of aiding continued aileron control, but wingvtwist, or varied angle of incidence, or similar are other common approaches to that problem. See Cessna, Cirrus, and Quest designs.
Comment: Okay@J Walters,I will
Comment: Are you building a computer model, or are you intending to make a modification to an existing aircraft, or experimental aircraft?
Comment: Am actually building an ultralight..... From scratch@KorvinStarmast
Comment: Recommend you include that detail in the question, since ultralights have their own unique problems to solve.
Answer: Vortex generators re-energize the boundary layer and can slightly postpone flow separation at high angles of attack. Therefore, adding them in front of a control surface is a realistic way of retaining authority. In fact there are real life examples:

[picture by Peter Kämpf]
That being said, these devices are a crutch that is best avoided on clean-sheet designs. They add drag in every flight condition in exchange for some more margin at high alpha, this margin could be achieved by designing the aircraft better in the first place. That is why you will mostly see vortex generators applied as fixes late in the design process or as outright aftermarket modification kits. This constant penalty is compounded by the extra maintenance needed to keep the VGs clean and in good condition.
Ultimately, re-energizing the boundary layer can only do so much to prevent separation. A hard down aileron input at high angle of attack can stall the wing even with VGs, they are not a silver bullet.
Answer: I wouldn't dismiss them so lightly. On my Cessna Cardinal, the VGs from MicroAeroDynamics
https://microaero.com/
did wonders to improve the airplane handling at slow speeds - the airplane is responsive at slow speeds now, has the same feel as at higher airspeeds (like 25-30mph faster), and really increased my confidence at low airspeeds.  I used to fly out of a 1680 foot strip, coming in over tall trees. Hot days, low winds, it was a real challenge to get slow enough to get on the runway before midfield and stop before hitting the fence at the far end. After the VGs, it became no problem at all - so much easier to get the plane flying slower and still handle well, it was no problem to be on the ground well before the midfield mark and turning off before the end.
At the other end, there is no noticeable impact to top end speed of around 145mph at 24"mp/2400 rpm.
The only time I stall anymore is during flight reviews with instructors, and I have to really work to get the plane to stall, power off or power on. And when it finally does, just pushing the yoke forward recovers it immediately, with little wing dip to either side. Same with unusual attitude recovery, a little push and aileron correction and straight & level is returned.


Is asking a series of questions discouraged?

Question: I was able to solve my problem based on the advice given here - Imake and header files but I would like to know whether I can continue to ask questions on the same topic one question at a time. Is this discouraged and closed or it is on topic at Unix and Linux SE ? By that I mean the software is not compiling and one fix leads to other errors. Can I ask my questions in a series related to compilation of the same product ? I will obviously space it out over time and I try my level best to solve it myself.
Answer: No, it is not discouraged to ask follow-up questions.
However, avoid asking a series of very similar questions, and avoid using questions and answers as an interactive chat session to debug a particular thing.
A section in our Help Center mentions

We like to help as many people at a time as we can. Make it clear how your question is relevant to more people than just you, and more of us will be interested in your question and willing to look into it.

along with

Have you thoroughly searched for an answer before asking your question? Sharing your research helps everyone. Tell us what you found and why it didn't meet your needs. This demonstrates that you've taken the time to try to help yourself, it saves us from reiterating obvious answers, and above all, it helps you get a more specific and relevant answer!

For your problem with imake:  I answered the question to the best of my ability, with the information given in the question.  Had you provided more information about exactly what piece of software you tried to build, I would possibly have been able to see for myself, on my own machine, what the issue was and come up with a much more detailed and complete solution.
One possible issue with a series of follow-up questions is that the individuals that look at the questions do not know what it is you're actually want to do.  You say you're wanting to do "X", but it's actually "Y" that is the main issue that you're trying to solve. It is conceivable that solving "X" might even make it harder to solve the real problem "Y".
For example, copying that site.def file to a new location may solve the immediate problem of it not being found by the build process, but in doing so, it may mess something else up further down the line.
This is why I initially just left a comment rather than an answer on that particular question. I knew that my imake-foo was not up to scratch and I wanted to give a workaround that might have worked (but it didn't actually work completely in the end).
Comment: If the software had a public URL for download I would have posted it in the question.  Unfortunately I got it via an associate. It is no longer supported.
Comment: @gansub Yes, that makes it harder to write a good answer. In this particular case, we may simply need someone with more `imake` knowledge. Note that I _not_ say "don't write a follow-up question", just that it's important to (try to) frame it in such a way that an answer actually solves the real problem.
Answer: Adding to @Kusalananda's answer:
As long as your question contains a Short, Self-contained, Replicable example, it's fine. It might be a good idea to link the other asked questions for reference; however, each question must be able to stand for itself.


On Judgement day, everything will be destroyed in the earth and heavens

Question: On the Day of Judgement everything in the heavens and earth will be destroyed, but what if humans would have inhabited other planets or even other galaxies by then, will they be destroyed?
Comment: Wouldn't you expect other planets and galaxies to fall under the umbrella of "everything"?
Comment: is all the land in this universe collectively called as "Earth" in Bible and Qur'an??? @goldPseudo
Answer: On the day of judgment, earth will not be the only thing to be destroyed, everything that exists, everything in the universe, every galaxy, everything that was created, will seize to exist (except Allah). So inhabiting other planets will not save any living being from the day of judgment
Answer: Islam teaches us how the existence will end.
We know when the angel Israfil will blow the soor, the qiyamah will begin.
Allah says in quran that the heavens and earth were one point adjoined, then he cleft them asunder. (separating them.)
Allah says in the quran "as we originated creation, so too shall we return it. This, a promise binding on us"
When the soor is blown the universe/multiverse will collapse on itself and return to that single intense point. This will destroy everything, from there Allah will remake the universe/multiverse however he sees fit.
Comment: Your answer would e more helpful if you could add references to support your claims. I also strongly suggest you to consider reading http://islam.stackexchange.com/help/how-to-answer


Release mechanism for car drop session

Question: Hello, we are doing a car drop session and everything else has been already planned apart from one last thing. I haven´t been able to find any reasonable system for the release mechanism that connects the car to the crane. I´ve bee looking for products such as Elebia e5 crane hook system and Henriksen HMKST 8.0, MOB-Hook, WLL 8.0 T Art No.: HH000028, with the conclusion that neither of these are optimal for such task. I´ve heard that magnetic "hooks" and suction devices could also be used to lift cars to roughly about 30 meters high. Frankly this stuff goes bit beyond my set of skills and knowledge so any ideas concerning the subject is greatly appreciated. It would also be preferable if we could rent the system for a day or two instead of buying. Thanks for your help!
Comment: This is a pretty great question/answer.
Answer: When I dropped cars, we used this massive forklift thing:
https://plus.google.com/photos/112773450273987656053/albums/5575619157179451041/5575619181206793730
The great thing about the forklift vs cranes, is that it is very quick, you don't have to rig up quick release systems, and there is no reset time.  The downside is that your operator has to shut the engine of the forklift off the second he releases the car.  This is the method that John Fasal uses and he's done more car drops than anyone will ever do, so he's got it all figured out.
More photos from my drop session here:
https://plus.google.com/photos/112773450273987656053/albums/5575619157179451041
Comment: Hmm.. That seems to work quite well, the only downside is that we wanted to get the cars up to 30 meter high. How much of kinetic force can you get with such height, do the drops sound violent enough?
Comment: @Chuck Russom how many cars did you use on this session?
Comment: @ Ville Sora Wow, 30 meters is pretty high!  I think we got ours up to 40 feet, which is 12 meters or so.  They are pretty damn violent sounding, I can't imagine needing anything more.
Comment: @RedSonic01 I think we did 12 cars, with multiple drops each, over 2 days.
Answer: Ok, for those who ever might need the similar kind of mechanism, we used 70 ton crane to pull cars up to 20 meters and a Henriksen hook and a rope worked just fine. I`m sure there are similar companies that build these kinds of maritime hooks all over the world and I suggest you try to either lend them or rent them as they seem to be extremely costly.
Its also worth mentioning that drops beyond 10 meters seem to have less texture and more of a less interesting "bang" due to the force of impact. Its also better to drop them to another car rather tahn pavement or metal plates, it also gives more detail to the impacts.

Release mechanism for car drop session


mp4 file has no sound

Question: I recorded an mp4 file with 41mins, when i open it it shows the size and duration and plays through the file but doesn't have any sound. Does anyone know a way how to try and repair this or is this audio lost?
Comment: Is there anyway you can share the file so that we can check it out?
Answer: Try opening the file with some advanced video players just to find out if the audio is gone or there's a codec error.
Two video players that I use when having this sort of problems is Quick Time and Video Lan.
If indeed there's no audio attached to the video - there's little to be done - maybe useing a disk data recovery tool depending on the recording medium, to get at least some of it back (if it was written on disk).
Answer: I've had this happen before, howevr it was while recording the screen of my computer. Not certain if you've done the same or used a camera IRL. However easiest way to see if there's audio in a file is to play the file in VLC and press CMD+I or CTRL+I (Window>Media Information)
Notice under CODEC Details "Stream 0" & "Stream 1". 0 is your video and 1 is your audio. If you see Stream 1 (or 2) you have an audio encoded into your video. Next jump over to the "Statistics" pane right of "CODEC Details", you should see a lot of numbers in each section of that pane and the most important two parts are the top left "Input" and the bottom right "Audio". If you see that all jolly good then you probably just gotta give it some gas (gain). Many streaming / video players support this but if you'd like to further investigate, I suggest using Adobe Audition or Adobe Premiere (or both but Adobe Audition is strictly for sound and it a very high quality program). Best of luck!
Answer: I might be late but I've had the same issue - I tested a bit around and for me the solution was making the .mp4's audio track stereo. Don't ask me why, but for some reason Windows Movie Maker decided to not play 'mono' sound in mp4. (My) problem solved.
I hope some souls with the same problem will find my solution here (though the conversation is 3 years old already).
Good luck!

mp4 file has no sound


Detecting TV power on/off without CEC

Question: Is it possible to detect when I turn on/off the TV? Unfortunately my TV does not support CEC, but I want to somehow stop the XBMC process when the TV is switched off (or uses a different source).
Answer: You could use the GPIO pins to attach some kind of sensor.
I'm checking to see if my stereo is on, using just a simple LDR. I placed the LDR inside the SPDIF output of my stereo. If my stereo is on, the is light coming from the SPDIF, and the the LDR will pull the GPIO pin low.
Works like a charm.
I found out that the LDR I used in combination with the build-in pull-up resistor inside the Pi's chip will result in a LOW if the stereo is on, and a HIGH if off.
So all I needed to do is connect one pin of the LDR to ground, and the other to one of the GPIO pins. No other components needed.
This is (part of) the script I use to control audio playback, only when the stereo is turned on.
#!/usr/bin/python
import RPi.GPIO as GPIO
import time
import subprocess

GPIO.setmode(GPIO.BOARD)
# LDR (LOW if stereo on)
GPIO.setup(7, GPIO.IN, pull_up_down=GPIO.PUD_UP)

playing = -1
while True:
    ldrState = GPIO.input(7)

    if ldrState == False and playing != 1 :
        subprocess.call("mpc play", shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        playing = 1

    if ldrState == True and playing != 0 :
        subprocess.call("mpc stop", shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        playing = 0

        time.sleep(.5)

Comment: Thanks for the idea, maybe I'll try this in the future, but for now it's enough for me to start/stop XBMC via SSH.
Answer: If your TV has a USB port, you could use a gpio pin to sense the voltage on the TV's USB power pins.
Remember to use a level shifter or opto-coupler because USB power will be 5 volts.
Answer: Sorry you cannot, unless you create some kind of hardware device, that watches if your TV is switched on or not by checking the current in the power cable or by looking at the screen through the web-cam, and write appropriate scripts to process the data and shutdown xbmc at the appropriate moment.

Detecting TV power on/off without CEC


Looking for a verb that would be the opposite of smear, from a political/public relations point of view

Question: I'm looking for a single word that would mean the opposite of smear. Specifically, I'm looking for it in the context of a verb being an action that an entity has at his disposal. So you might have a dirty snook who has "Smear 4", or the ability to lower someone's public relations rating by 4 points. If you were the victim of a "Smear 4" you would need to hire your own consultant with "Unsmear 4" to get your public relations back to where they were before the smear campaign was run against you. Clearly, "Unsmear" is not a viable term. I've reviewed a number of thesauruses, but nothing really jumps out at me. The closest I've found is either flatter or glorify, but neither convey what I'm looking for. I'm looking for something that evokes images of kissing babies, attending ice cream socials, and other typical PR boosting stuff.
Comment: _Whitewash_ may fill the bill.
Comment: _Puff-piece_ is an article written to make someone look better.
Comment: @ΜετάEd I disagree that the question is not constructive. I researched single word requests on meta before and after posting this question. My primary criteria were [here]http://meta.english.stackexchange.com/a/1659 and I believe I hit no 'bad' criteria, and all of the 'good' criteria.
Comment: @Downvoter If you have ideas as to how this post could be improved, I'm all ears (eyes?).
Comment: "kissing babies, attending ice cream socials, and other typical PR boosting stuff." Sounds like *presidential campaigning* to me.
Comment: "Whitewash" is possible, though that means to attempt to cover up bad behavior. If the person is really innocent of wrongdoing and the attack is unfair, you wouldn't call the defense a "whitewash". Well, the other side might, but that would be more smear.
Comment: Is this for...a game? Do you want the opposite or just the zero state? Do you want it for _a_ smear (a noun) or for smearing (a verb). 'flattery' is a noun, 'stroke' is a verb. Did you look in a thesaurus first?
Comment: If you mean specifically defending against a smear attack and not positive statements about yourself in general, I don't know of any term besides "reply to the smear".
Comment: Answers should be posted as answers instead of comments. Also, this question can't be answered definitively: it is no more than a poll, with the OP choosing a "favorite". Voting to close Not Constructive. +1 for checking a thesaurus first.
Answer: The term hype is often used to play up or enhance a reputation.  According to Cambridge

to make something seem more exciting or important than it is

Three additional definitions from American Heritage say

Excessive publicity and the ensuing commotion: the hype surrounding the murder trial.
Exaggerated or extravagant claims made especially in advertising or promotional material: "It is pure hype, a gigantic PR job" (Saturday Review).
An advertising or promotional ploy: "Some restaurant owners in town are cooking up a $75,000 hype to promote New York as 'Restaurant City, U.S.A.'" (New York).

This is not unsmear but a concept of promoting.
Another aspect of countering a smear would be a rebuttal. Again Cambridge

a statement which says that something is not true; She issued a point-by-point rebuttal of the company's accusations.
Comment: I do really like hype, in that it also works in the context of never having been a victim.
Comment: I like "hype." The word I would most naturally use for what is described here is probably "promote" - to _promote_ a candidate - but taken out of context it might be problematically confused with the "ascend to higher rank" meaning.

Another option, which I thought of because OP unwittingly used it in their post, is **boost**.
Comment: @alcas Boost is a good option. Unfortunately, in the context of the game (these are abilities of entities in a game) boost would be ambiguous, as there are a number of other statistics that could be boosted.
Answer: To "spin" is political jargon for attempting to frame news or events in a manner favorable to yourself or your group. As in, "Stories are coming out about our candidate having numerous extra-marital affairs. We've got to spin this as 'popular with women voters'?"
But this is broader than just "undo the negative impact of a smear". It's also routinely used to refer to making an ambiguous fact look good for your side, or turning something potentially positive about an opponent into a negative.
Comment: I do like "spin", particularly because of how broad it is. It's very similar to "hype" as mentioned above, although not as broad. That is to say, hype can exist without a driving element - things can be (and most often are) invented to be hyped, while spin requires a driver to be spun.
Answer: Most positive I can think of is polish.
Smear implies covering with dirt, whitewash implies covering it up.
But if there is no dirt in the first place, and there are genuine merits to be highlighted, it is time to polish them up.
'Their smear campaign has hurt us. It is time to polish up our reputation.'
Answer: The opposite of a smear in P.R. is what is known as a puff piece or puffery:

Puff piece or fluff piece is an idiom for ... an article or story of exaggerating praise that often ignores or downplays opposing viewpoints or evidence to the contrary.
Comment: Puffery would fit the particular theme of the game being developed,  although I'm not sure it would be intuitive. The term would be "Puff 4" (which sounds more like smoking illegal substances) or "Puffery 4" (which to be honest sounds like a delicious bakery item). Both of those in their intuitive conext fits the theme of the game (an underhanded businessman doing anything to get ahead) and certainly has uses, but I'm not sure fits this particular application of it.
Answer: Lionize is a wonderful word.
Oxford Dictionary of British English:

give a lot of public attention and approval to (someone); treat as a
celebrity: modern sportsmen are lionized and feted.

Some uses of it together with politicians on Google:

Will Dem re-enacters recreate the Chappaquidick incident as they lionize Teddy?
Requiem for a Reprobate: Ethiopian Tyrant Should Not Be Lionized

Some other possibilities are panegyrize, commend, laud.
Comment: I had considered commend, but it seemed too real. That is, you need something to be commended for, and the PR campaigns that would be run are based much more on nothing than they are on something (if *that* made any sense!) As far as lionize, I actually agree with your description of 'wonderful' - but would my users also 'wonder' what it means?
Comment: I had the idea laud always went with magnify, but per [ngrams](http://books.google.com/ngrams/graph?content=laud%2Claud+and+magnify&year_start=1500&year_end=2008&corpus=0&smoothing=3) for *laud,laud and magnify* not so much.
Answer: Have you considered exalt?  From OED:

a. To raise in rank, honour, estimation, power, or wealth.
d. To praise, extol, magnify.
e. To raise to a higher class, a higher degree of value or excellence; to dignify, ennoble
f. To stimulate (powers) to higher activity.
Comment: It crossed my mind, but there are two cons against it. One is the MTG mechanic *exalted*, and the second is the inherent religious connotation associated with the world exalt. Despite the image that underworld figures have of being highly religious, it doesn't seem appropriate given the context - a context that you personally are more familiar with than any other poster ;-O Ohhh no I've said too much.
Comment: ... and it's rarely used in a political context. In practice, we just don't say "We must exalt Senator Jones".
Answer: The first answer that sprang to my mind, when thinking about the "opposite" of smears – at least, in the realm of politics – are endorsements.
Former presidents and sitting politicians often endorse the campaign of another politician (presidents and former presidents endorse those running for the Senate; senators endorse those running for mayor, and so on.)  Moreover, mainstream news outlets (newspapers, magazines) will often endorse a candidate on the eve of an election, giving glowing, impassioned arguments on their opinion pages.
But you ended your question by mentioning:

I'm looking for something that evokes images of kissing babies, attending ice cream socials, and other typical PR boosting stuff.

Those are often referred to as photo ops (ops being short for opportunities).
Comment: This is very insightful, and I do like both terms. I get the feeling, though, that they are instances of what I seek. That they are too specific for the particular application in question.
Comment: @corsiKa: Good call. _Photo op_ as "an instance" is an astute observation; I think you're right. What I like about _smear_ vs _endorse_, though, is that they can both be used as nouns or verbs, and still work as antonyms.
Comment: Endorse would work, but it would require the endorser to be someone important. If a nobody were to come forward with a story about how you saved their cat, it wouldn't be much of an endorsement... who wants to be endorsed by the guy who let his cat require saving in the first place?
Answer: The word you want is "stroke".  The Free Dictionary gives it as a verb (section 2, definition 2) but it is also used as a noun.
Comment: Being a verb is preferable to being a noun, as it's an action an entity performs. This does seem to fit the bill, but I see two problems with it: 1) it's fairly obscure, so it's meaning would be learned by users as opposed to intuitively apparent, and 2) teenage users would never live it down...


Is there an otherwise liquid material that has angle of repose?

Question: I wonder whether there is a material which consists from individual molecules (that is, fluid), which has its angle of repose thus exhibiting propertes of a powder?
Answer: A liquid by definition has no fixed shape and therefore can have no angle of repose. I have noticed you have asked a similar question on Physics.SE; the presence or absence of this kind of property can be used as a means to classify powders versus fluids.
Note also that the conical "fixed shape" observed in powders is due to frictional forces between the particles, whereas any surface curvature in liquids from surface tension (e.g., a meniscus) is due to intermolecular forces between individual molecules.
Furthermore, take into account the melting point of the substance: it's a powder if the temperature of interest is below the melting point, and a liquid if it is above.
Answer: Such materials are called Bingham plastics.  An angle of repose means that the material must withstand a non-zero shear stress (from its own weight) while still exhibiting zero shear rate.
Examples include toothpaste, ketchup, mayonnaise, latex paint, and concentrated suspensions of coal particles in a otherwise newtonian liquid.  I'm not sure if any of these materials meets your requirement that it consist "of individual molecules".  I don't think a single-component, single-phase, non-polymeric substance will ever exhibit Bingham plastic behavior, although (I might be wrong and) I can't cite any theoretical reason why this is so.
Comment: Do they really have angle of repose?
Comment: Imagine a large tank of ketchup.  You stick a one end of a long pipe straight into the surface of the ketchup, and let the other end be a large height above the bulk surface.  Fill the pipe with ketchup, and after it is full, remove the pipe.  The large column of ketchup will collapse into the bulk, but not completely.  There will be a small pile left that will have some maximum angle w.r.t. the bulk surface normal.  Isn't that an angle of repose?


Broken image URL

Question: I seem to be having a problem with broken URL links in posts for images. If you click on the image from the post you will see the URL but if you try to then copy and paste that URL it will show as a broken link.
Here is a test page I put together to try and figure this out:
http://www.sixteeneighteen.co.uk/2013/04/work/
If you click on the image it'll show the url as http://www.sixteeneighteen.co.uk/wp-content/uploads/2013/04/remove01.jpg
but if you then try to refresh this page or copy and paste the link it won't show I've been playing with file permissions and that doesn't seem to do anything they are set to 755
I've looked everywhere online for something similar but can't seem to find any answers, any help would be greatly appreciated.
Many thanks
Comment: Its working for me http://www.sixteeneighteen.co.uk/wp-content/uploads/2013/04/remove01.jpg
Comment: Its working fine for me. Kindly clear the cache by ctrl+f5 and check it.
Answer: It worked for me. http://www.sixteeneighteen.co.uk/wp-content/uploads/2013/04/remove01.jpg
i dont see any problem with the link.

Broken image URL


No HDMI sound on Ubuntu 12.04 LTS

Question: I'm very new to Ubuntu/Linux.
I installed Ubuntu 12.04 LTS on my laptop (nVidia gpu) in dual boot, and, with some help from Google, I'm almost ready to go.
The only thing that I can't figure out is how to play sound trough my HDMI connected to my TV. Speakers of the laptop are ok, in the sound settings I can see -hdmi -digital -speaker outputs. The top 2 won't play sound so I Googled around, found a bunch of things to try but the only thing successful so far was to erase all the drivers from the audio settings and they stayed gone. So finally I re-installed from scratch but still no sound trough HDMI. I tried reinstalling several times, but it didn't work. How can I play sound on my TV connected with HDMI?
I will be glad to give more info if needed cuz this is driving me crazy,
thanks for your help in advance!
Answer: I Installed alsa control, un-mute everything and sound was ok.
<code>sudo apt-get install alsamixergui
</code>

No HDMI sound on Ubuntu 12.04 LTS


configure error: C compiler cannot create executables

Question: I was trying to install rvm ( \curl -L https://get.rvm.io |    bash -s stable --ruby --autolibs=enable --auto-dotfiles). It worked fine until ZI got a configure error:
Error running './configure --prefix=/home/nishant/.rvm/rubies/ruby-2.0.0-p247 --disable-install-doc --enable-shared',
please read /home/nishant/.rvm/log/1379591052_ruby-2.0.0-p247/configure.log
There has been an error while running configure. Halting the installation.

Following are the contents of the mentioned log file:
[2013-09-19 17:15:58] ./configure
current path: /home/nishant/.rvm/src/ruby-2.0.0-p247
command(4): ./configure --prefix=/home/nishant/.rvm/rubies/ruby-2.0.0-p247 --disable-install-doc --enable-shared
checking build system type... i686-pc-linux-gnu
checking host system type... i686-pc-linux-gnu
checking target system type... i686-pc-linux-gnu
checking for gcc... gcc
checking whether the C compiler works... no
configure: error: in `/home/nishant/.rvm/src/ruby-2.0.0-p247':
configure: error: C compiler cannot create executables
See `config.log' for more details

I then tried a "hello world" C program and got the following error on compilation:
nishant@nishant-Inspiron-1545:~$ gcc -g -o hello hello.c
/usr/local/bin/ld: this linker was not configured to use sysroots
collect2: error: ld returned 1 exit status

I'm not sure why this error is thrown. I couldn't find a satisfactory answer to this on the forum. Could someone please help.
Thanks
Answer: I had the same problem, that I solved buy installing certs and libs for building C programs
apt-get install build-essential


How to read barcode from ASP.NET?

Question: I'm not sure, is this possible or not? I want to scan barcode from within ASP.NET website. Anyone know how to do this?
Comment: I would provide a file upload control and then do some barcode "OCR" on the server.
Comment: check this out: http://sourceforge.net/projects/itextsharp/
Comment: http://silverlightbarcode.codeplex.com/
Answer: You would need a scanner and the relevant software to interact with the scanner. Most hand held scanners simply output the text into whatever field is in focus, so this could be Notepad, Word, or even a textbox in your app.
Best approach is to find a scanner that suits your needs and then look into the Driver software it provides.
Answer: The simplest way would be to use Flash to gain access to a user's web cam and have them place the barcode infront of the camera. I'm sure Silverlight can do this as well.
No matter how you cut it, though, you're going to need to use some sort of third-party control, whether Flash/Silverlight, Java applet, or browser extension/addon.
An alternative would be to use a specific brand of barcode scanner whose software can insert the results into an arbitrary textbox.

How to read barcode from ASP.NET?