How to remove ball pen marks from the clothes?

Question: I got a lot of drawing from ball pens on my clothes. I tried washing them with soap, but that didn't help. How can I successfully remove ball pen marks from my clothes?
Answer: First off, you need to determine what kind of ink stain you're dealing with.
Not all pens with a ball are actual "ballpoint" pens.

Traditional ballpoint pens (like the ubiquitous Bic and Paper Mate) use a fast-drying, oil-based ink that requires a solvent to remove.1 Rollerball pens, on the other hand, (common manufacturers include Uni-Ball and Pilot), use water-based inks that are fairly easy to remove, while gel pens use a highly-pigmented type of ink that can be a bit more difficult.2

If you're certain it's an oil-based ink:

Find a suitable solvent. Common isopropyl alcohol is suitable for most stain-removal jobs and can be purchased generically at a pharmacy, for example rubbing alcohol.
Place the stained garment on several layers of paper towels, so the ink has somewhere to go.
Apply your alcohol-based solvent of choice.
Wait 3-5 minutes. The solvent needs a few minutes to break down the oils in the ink.
Blot the stain using layers of white paper towels.
Repeat as needed.

If it's water-based ink:

Soak the stained garment in (skim) milk.
Wait for at least half an hour.
Scrub the stain gently with a toothbrush, cuticle brush or similar soft-bristled brush.
Rinse thoroughly with warm water.

And if it's highly-pigmented ink:

Hand-wash with soap or regular detergent as quickly as possible.
Rinse thoroughly with running water.
Try to blot any remaining ink by pressing the fabric between two absorbent cloths, or stacks of napkins or paper towels.

Dissolve 1 teaspoon of ammonia in warm water.
Soak the garment in the ammonia solution for one hour.
Repeat steps 1 & 2 and scrub with a soft brush, if needed.

If the stain is responding to this treatment, repeat as needed until the ink is gone, and launder as usual.

Mix 1 cup of rubbing alcohol with 1 cup of vinegar.
Place the garment on a clean, dry towel and apply the solution.
Let it soak for at least 5 minutes.
Pour a small amount of table salt over the stain.
Wait 10 minutes.
Scrub with a soft brush and rinse with hot water.

If the stain is responding to this treatment, repeat as needed until the ink is gone, and launder as usual.

You may have to experiment with the above steps (hence the horizontal lines) or try other methods. Just make sure to rinse the garment very thoroughly between different methods to avoid mixing chemicals.

Sources:

about.com - How to Remove Ball Point Pen Ink
wikiHow.com - How to Remove Ball Point Pen Stains from Cotton
about.com - Steps to Remove Ballpoint, Permanent, and Water-Based Ink
Answer: I don't know if it works on every pen, but I have removed ball point pen ink from clothing a couple of times with aerosol hair spray. It worked very well. It also took ballpoint pen stains out of my dryer.
Comment: I don't know whether that applies to all hair sprays, but from the first source in my answer: `hairspray usually will remove ink, but it should only be used as a last resort because hairspray damages some surfaces and fabrics`
Comment: I have never had a problem with it, but that certainly makes it sound like it warrants some caution. :) I know it does not damage the inside of a dryer. Plus, if it is so bad for fabric, it is safe to use on hair? Most people apply it while wearing clothing. :)
Answer: I have had excellent results using trichloroethane for dissolving oil-based stains.
Comment: Yes, tric is an excellent solvent for this.  However, it is almost impossible for the public to get hold of because it is so toxic.
Comment: In New Zealand I have purchased it from pharmacies, and in the Netherlands I have gotten it from drug stores. Not sure about other countries. Although obviously you should use adequate precautions as for any solvent, it was used in whiteout correction fluid sold in stationary stores for years so I wouldn't imagine it's quite that toxic.
Answer: Getting pen marks, dots and lines on the back of your shirt is very common as a student. Because we always sit one behind the other and slipping of the pen is common. I have myself got many such designs on my new and expensive shirts. I once wore a costly casual plain white shirt to college. The person behind me had a Reynolds waterproof gel pen. He was very careless in handling it. So there were all zig zag lines on my white shirt at the end of the day. There was no way I could remove the lines.
As I am experienced in this, let me tell you.
1. Roller ink pen stains on your shirt are easy to remove as they are water based
2. Ball point pen marks will gradually disappear if you wash with alcohol
3. However if someone has used a waterproof gel pen or a marker on your shirt, you will never be able to get rid of it. Either throw it away or continue wearing it.
So please don't wear any expensive light coloured shirts to places where there is a danger of pen marks.


Prove that $\sum_{k=0}^n k^2{n \choose k} = {(n+n^2)2^{n-2}}$

Question: Prove that: $$\sum_{k=0}^n k^2{n \choose k} = {(n+n^2)2^{n-2}}$$  i know that: $$\sum_{k=0}^n {n \choose k} = {2^n}$$ how to get the (n + n^2)?
Comment: Where I can get proof for $\sum_{k=0}^n {n \choose k} = {2^n}$?
Comment: @Avra https://en.wikipedia.org/wiki/Binomial_coefficient#Sums_of_the_binomial_coefficients, https://mathworld.wolfram.com/BinomialSums.html.
Answer: Differentiating the binomial expansion
$$
(1+x)^n=\sum_{k=0}^n\binom{n}{k}x^k,
$$
we obtain
$$
n(1+x)^{n-1}=\sum_{k=0}^n k\binom{n}{k}x^{k-1} \quad\Longrightarrow\quad
n2^{n-1}=\sum_{k=0}^n k\binom{n}{k} \tag{1}
$$
and
$$
n(n-1)(1+x)^{n-2}=\sum_{k=0}^n k(k-1)\binom{n}{k}x^{k-2}
\Longrightarrow\
n(n-1)2^{n-2}=\sum_{k=0}^n k(k-1)\binom{n}{k}. \tag{2}
$$
Adding $(1)$ and $(2)$ we obtain
$$
n(n+1)2^{n-2}=\sum_{k=0}^n k^2\binom{n}{k}.
$$
Comment: @Avv that's a special case of the binomial theorem.
Comment: Thank you. Where I can get proof for $(1+x)^n=\sum_{k=0}^n\binom{n}{k}x^k,$?
Answer: Hint: The derivative of $(1+x)^n = \sum_{k=0}^n {n \choose k} x^k$ with respect to $x$ is $\sum_{k=0}^n k {n \choose k} x^{k-1}$. Can you see how to apply this twice and combine results to get your identity with $x = 1$?
Comment: This has a finite calculus feel to it. I like it :)
Answer: We have a group of $n$ people in a class. We want to choose $1$  or more of them to go on a special trip. And we want to appoint one of the people who goes on the trip Leader, and one of the people Treasurer, where Leader and Treasurer could be the same.
Then the number of ways to choose the people who will go on the trip, and assign the special awards, is $\sum_1^n k^2\binom{n}{k}$. (Whether we start summing at $0$ or $1$ does not matter.)
We count the ways to do the choosing in another way. We can choose $1$ person to be both Leader and Treasurer, and then choose a subset of the rest to also go on the trip. There are $n2^{n-1}$ ways to do this. Or else we can choose different people to be Leader and Treasurer, and get a subset of the rest to join them. This can be done in $n(n-1)2^{n-2}$ ways.
Add. We get $(n)2^{n-1}+n(n-1)2^{n-2}=(2n)2^{n-2}+n(n-1)2^{n-2}=(n^2+n)2^{n-2}$.
Answer: Alternative proof using no calculus, no combinatorics, just pure algebraic manipulation starting from the special case of the binomial theorem:  $$\sum_{k=0}^n \binom{n}{k} = 2^n.$$  We also note the identity $$\begin{align*} \binom{k}{r} \binom{n}{k} &= \frac{k!}{r! \, (k-r)!} \cdot \frac{n!}{k! \, (n-k)!} = \frac{n!}{r! \, (n-r)!} \cdot \frac{(n-r)!}{(k-r)! \, (n-k)!} \\ &= \binom{n}{r} \binom{n-r}{k-r}. \end{align*}$$
Then $$S_1 = \sum_{k=0}^n k \binom{n}{k} = \sum_{k=1}^n \binom{k}{1}\binom{n}{k} = \binom{n}{1} \sum_{k=1}^n \binom{n-1}{k-1} = n 2^{n-1}.$$
Similarly, $$S_2 = \sum_{k=0}^n k(k-1) \binom{n}{k} = 2 \sum_{k=2}^n \binom{k}{2} \binom{n}{k} = 2 \binom{n}{2} \sum_{k=2}^n \binom{n-2}{k-2} = n(n-1) 2^{n-2}.$$
Consequently, $$\sum_{k=0}^n k^2 \binom{n}{k} = S_1 + S_2 = n(n+1)2^{n-2}.$$  In this manner, we can recursively evaluate sums of the form $$\sum_{k=0}^n k^m \binom{n}{k},$$ using the general identity $$\sum_{k=r}^n \binom{k}{r}\binom{n}{k} = \binom{n}{r} 2^{n-r}.$$
Comment: Where I can get proof for $\sum_{k=0}^n {n \choose k} = {2^n}$?
Answer: How about a solution with combinatorial interpretation?
For any given subset of $n$, choose $k$ elements, then choose $2$ elements from this $k$-subset in an independent way. This is how we can look on the left side of the equation. There are $2$ ways of doing this:

either we choose the same element twice, or
we choose different elements,

Hence the addition $n^2 + n$ on the right side.
Answer: Its a bit easiler to evaluate up to $n+1$.
I will use the identity that $\dbinom{a}k = \frac{a}k \dbinom{a-1}{k-1}$.
$\sum_{k = 0}^{n+1} k^2 \dbinom{n+1}k$
$ = 0+1 \dbinom{n+1}1 + 4 \dbinom{n+1}2 + 9 \dbinom{n+1}3 + \cdots + (n+1)^2 \dbinom{n+1}{n+1}$
$ = 0+(n+1) \dbinom{n}0 + 2(n+1) \dbinom{n}1 + 3 \dbinom{n}2 + \cdots + (n+1) \dbinom{n}n$
$ = (n+1) \left( \sum_{k = 0}^{n} (k+1) \dbinom{n}k \right)$.
This can be easily evaluated from the derivative of $x(1+x)^n$.


Covered call and put options as separate trades

Question: Let's say I write a covered call and a buy separate put option. After a period of time, the call expires, leaving me with the underlying stock. Thereafter, the market price went down and I can exercise my put option. Will the underlying stock that I own before be use for the assignment?
Comment: Yes. Of course, you can always buy more stock at the current price and sell it at the put strike price if you want to keep your original stock and just want to "cash out" the long put.
Comment: If the original stock is sold at a loss, it will create a wash sale violation if the replacement stock was bought within 30 days before or 30 days after realizing the loss.  In that case, the loss will be deferred until the second position is closed. In addition, you will have to designate that you broker sell the second lot of stock and have written proof of that otherwise the IRS will default to FIFO.
Answer: Yes, if the call expires worthless, leaving you with stock. Then you can exercise your put when the stock goes below put strike price.
Answer: Owning 100 shares and selling a covered call to fund the purchase of a put is called a long stock collar.  If the strikes are different, it is equivalent to a vertical spread.  If they are of the same series, it's a conversion.
The only way that you could exercise your long put to sell the stock AFTER the short call has expired would be if the put expired at a later date than the short call.


Is a brad nail gun suitable for attaching pickets to a fence?

Question: I have a large fencing project and I'm thinking about purchasing this nail gun:
RIDGID 2-1/8 in. 18-Gauge Brad Nailer:

Would this be suitable for attaching pickets to the rails, or is there a better tool for this?
Comment: You could use it to quickly fix the planks in place, then put in large nails by hand without having to hold the planks at the same time.
Answer: No -- an 18 ga. nailer is ideal for attaching small pieces of trim, like shoe molding/quarter round, inside your house. Outside, the nails will quickly rust and fall off -- they aren't galvanized, they are TINY, and they have little to no head on them. If you want to use a nailer, you need to use a framing nailer like Shirlock suggested. Make sure you use hot-dipped galvanized nails.
Personally, when building a fence, I use coated decking/exterior screws. They won't allow boards to warp and move like nails will, they absolutely won't ever rust unless you stripped the coating off somehow, and if you need to replace a fence plank because it cracked/warped/discolored, or you need to repair storm damage, or you need to remove an entire run of fencing to get a pickup truck or a large piece of equipment into the backyard, you can just unscrew a couple of screws. I haven't used nails for fencing in several years, and I've been happier as a result.
Comment: Just to follow up on this…I purchased a screw gun to put pickets up.  One of the best purchases I've ever made!
Answer: I think you will find that 18 gauge is way too light for your needs. I know that a lot of guys use finish nails for spindles and some light weight fencing, but I'm old school and prefer a headed galv nail, preferable threaded. At a minimum, I think you should use 16 gauge galv nails. Depending on the picket and rail dimensions, if meaty enough, I'd recommend a framer gun with 2" to 2 1/2" 4D galv ring shank nails. I guarantee these nails won't back out over time.


Test on a set of high degree polynomials whose coefficients in {-1,0,1}

Question: I'm looking for the best way of implementing the following algorithm: consider the set of all polynomials with a high degree (say, degree 30) whose coefficients ranges from a given set of values (say, {-1,0,1}). To any polynomial of this set, I want to apply some test (say, to verify if all its roots are real). If the polynomial pass in the test, I want to print it and its roots (numerically evaluated). If it does not pass, do nothing. (actually, my test is somewhat more complicated than this, but this is enough to clarify my point).
In the example above, I do not need to evaluate the roots of each polynomial in the set to verify if its roots are all real or not, since I can use instead, for instance, the Sturm theorem, or some numerical algorithm for isolating the roots intervals, and also other intermediate filter-tests as Descartes's rule of sign and so on. It is only when the polynomial pass on all these tests—so that I'm sure that all its roots are real—that I want to print the polynomial and its roots.
The problem is the following: since the degree is very high, there are too many polynomials to test for. This takes a high computational time even to run the list only. Therefore, I want to know what is the best language to implement the code and what is the best way of generating the list of polynomials for run the tests. Currently, I implemented the code on Maple, through a nested loop structure (one for loop for each polynomial coefficient), but I believe that there is a smarter way to do that. Maybe some way of parallelizing the loops would be desirable.
I do not master any programing language, but I can learn fast. I'm comfortable with Maple, Mathematica and I'm learning SageMath. I know a little of Python as well and I think that Cython is a good idea to implement the code, but I'm not sure … Any help will be very welcome and I thank you all in advance.
Answer: You can use backtracking to generate your polynomials. This can be parallelized in pretty much any language you choose. You may also want to call the Sturm sequence finder in the FLINT library from your script for speed.


How much do roof racks hurt gas mileage?

Question: I'm going on a big national car trip, and I want to increase cargo space by getting a roof rack, but I'm wondering how much the additional drag will increase my gas bill.  Is there any way to figure this out?
Comment: Please remember that there are two different mpg's: US and UK. mpg is "miles per gallon" - unfortunately there are two different gallon sizes used, a US gallon of about 3.78 litres and an UK gallon ("imperial gallon") of 4.54 litres. As a result, the same car that does 50 mpg in the USA does 60 mpg in the UK. Fuel consumption is made up of several components: Losses in the engine, rolling resistance, and wind resistance. The roof rack will mostly increase the wind resistance, and wind resistance grows enormously with speed, much more than rolling resistance. So a slight reduction in speed will
Comment: This greatly depents on the car. As shown in another answer with a small car (with a small engine) it will greatly affect fuel usage (but i'm shocked on the 50%). I've recently fitted a roofrack on my jeep and hardly noticed the difference. This is partly because of the brick like aerodynamics and because of large diesel inside. The only answer I can give is that depending on your type of car your milage can change by as much as 50% or as little as 2%.
Comment: @HTDutchy it also depends on the driving speed and the weight of the cargo.
Comment: There is no way to correctly determine this. Other factors (such as driving with the window down, the type and configuration of cargo, number of passengers, tires and tire pressure, engine configuration, elevation, gearing) also affect your fuel efficiency.
Answer: ConsumerReports.org has done the analysis.  Obviously it'll be different for every car and shape and size of roof rack, and contents of the rack, but in their experiment:
<code>2013 Honda Accord (4-cyl.)       MPG (Miles Per Gallon) @ 65 mph  = 105 km/h
----------------------------------------------
No rack                             42 mpg     =  5.6 l/100km
Empty rack                          37 mpg     =  6.4 l/100km
Empty rack and wind deflector       35 mpg     =  6.7 l/100km
Rack with two bikes and deflector   27 mpg     =  8.7 l/100km
</code>
So that gives you an indication that it can add close to 50% to your fuel bill, depending on the load.
Comment: It doesn't matter if the measurements are in MPG or Light Years per Flanian Pobble Bead, it's the relative difference between them that matters.
Comment: note that MPG is a notoriously bad metric for comparisons: http://datagenetics.com/blog/april12014/index.html
Comment: @MichaelBorgwardt no MPG isn't the inverse of fuel efficiency.  More MPG means more fuel efficiency.  l/100km is the inverse.
Comment: @Doc: yes, it matters, because MPG is the *inverse* of fuel efficiency, which leads to counterintuitive behaviour whe you use it to reason about the latter. See my link for details.
Comment: What's the purpose of a wind deflector, considering its effect is to *worsen* fuel efficiency?
Comment: @MichaelBorgwardt Moreover, *Three significantly different sizes are in current use: the imperial gallon (≈ 4.546 L) which is used in the United Kingdom, Canada, and some Caribbean countries; the US gallon (≈ 3.79 L), which is used in the US and some Latin American and Caribbean countries; and the least-used US dry gallon (≈ 4.40 L).*.  If a Canadian or Brit talks about "miles per gallon", what gallon does xe mean?
Comment: Also, I'm not sure this answer addresses the original question.  Consumer Reports seems to have done their test with bikes in mind not cargo/luggage in a box as Finnish test did.
Comment: That's getting off-topic, keep these discussions to the [chat] ;)
Comment: @MarkMayo: Are you aware of comparable data for an aerodynamic cargo box, which is what I'm looking at? Bikes must have a terrible effect on the resistance, but maybe a wing shaped box isn't so bad?
Comment: @JoshuaFrank road bicycles are extremely aerodynamic, as it makes a several mph difference.
Comment: @gerrit the wind deflector reduces wind noise from the rack and is, to some, aesthetic choice.
Comment: What kind of rack did Consumer Reports use?  I would think that would make a difference.
Answer: A local newspaper here in Finland recently ran a fuel efficiency test that might provide some relevant data here.  The original article is, alas, in Finnish only, but I'll summarize the results below.
The test compared the fuel consumption of the test vehicle (a Volvo V70 D4 diesel), on a test route that included both highway and urban driving, in three rooftop configurations.  The results were:

No roof rack: 5.6 l / 100 km (≈ 42 mpg)
Roof rack with Thule Dynamic 800 aerodynamic cargo box: 5.9 l / 100 km (≈ 40 mpg)
Roof mounted Thule Xtender 739 ski carrier with skis: 6.0 l / 100 km (≈ 39 mpg)

Thus, the cargo box on the roof increased fuel consumption by about 5% compared to the baseline.
(The full test also measured the noise level at the driver's ear, and compared the ease of installation and various other aspects of the different options, but I'll leave those out of this summary.  Suffice to say that the cargo box caused some steady but noticeable hum, and made the car somewhat more sensitive to side winds.)
Comment: It's billed as an aerodynamic box, and if that figure is correct then it certainly is just that - only 5% effect is pretty great! This would seem to indicate that the design of the box - or lack there of - is very important in determining the effect on gas mileage.
Comment: @BrianDHall other important factors are the driving speed and the weight of the cargo.
Answer: Short answer: It depends tremendously on who you ask and what vehicle is used.
An empty rack has been reported to increase the cost of fuel over time from anywhere from 1% to 15%, while a fully loaded roof rack will add 20% to 50% to your fuel bill. I'll justify these numbers below.
Note that however the exact same sources put the effect of "driving behaviors" at a shocking 35% - so the difference in calming down, using cruise control, and being in a relaxed travel mood while avoiding lane changes is about the same as putting on a roof rack and stuffing it full of bags, depending on your vehicle.
Methodology and citations below.
Sources: Consumer Reports - While this is reported in another answer, it solely uses MPG figures which are terribly bad for cross-comparison, and the empty-roof rack effect seemed so ridiculously high that it made me suspicious. Reports on different vehicles reported at little as a 1% reduction with an empty rack, so YMMV.
Edmunds.com - A multi-vehicle comparison with lots of assorted tests are run, and the data appears to be correctly interpretted into % savings.
Using a 2013 Honda Accord and data provided by Consumer Reports, an empty roof rack will increase the amount you spend on gas by 12% compared to no rack at all, assuming highway speeds. A two-bike rack with wind deflector will increase your gasoline costs by 36%. I am somewhat suspicious of this first figure, but it's possible.
Using a 2008 Buick Enclave with data from Edmunds, empty rails add only 1% to fuel costs but one suitcase and a cooler gave a 21% increase in fuel costs.
I very much like the Edmunds article for it's comparison of driving behavior, A/C usage vs rolling the windows down (verdict for the truck they tested: windows down better than A/C usage), however there still is little comparison amongst vehicles in the same conditions. In my 2010 Chevy Cobalt, for instance, I find A/C has an indiscernible effect on gas mileage possibly due to how the car is engineered, but this is not with scientific testing principles at all.
Final words:
There appears to be a definite effect of loading luggage onto the roof of a car, and it is very likely in the neighborhood of 20-50% regardless of vehicle.
The reason is quite logical - the top of a vehicle is the worst possible place to put things, from an aerodynamic point of view. It tremendously adds to forward-facing surface area that directly hits the wind, it completely screws up the entire wind envelope for the rest of the vehicle, and it does this usually less than 1/3 of the distance into the length of the vehicle; you've basically completely thrown out all aerodynamic gains in the engineering of the entire vehicle, you might as well drive a giant cube.
On the other hand, what if you are already driving a big cube which isn't terribly aerodynamic to start with? Well, I just don't know, but I'm sure putting things on top will make it worse.
However, driving behavior can clearly have an effect as big as a roof rack, so don't stuff luggage inside the cab, annoy the inhabitants, and make yourself want to get there faster - you'll end up losing a lot of money that way!
As to exact or even more precise effects than this rather large range of 20-50%, it appears that bigger, heavier, stronger-engined vehicles are likely to show a smaller % change from roof-racks than smaller, more aerodynamic, lower-powered engine vehicles.
For short trips it probably won't matter, as your gas bill won't be all that high anyway...but if you are talking about a cross-country tour, that little roof rack can cost you a few hundred $ pretty quick.
Answer: The answers posted are in line with my experience.  I recently traveled in a 2014 Audi A6 3.0 TDI on a trip to pick up my daughter at college.  Round trip was about 800 miles.
On the roof was a Rhino Rack with oval shaped cross beams and on the rack was a mountain bike and Yakima box filled with items such as duffle bags, books, etc.  Inside the car were more items plus my wife and daughter, and myself and the rear trunk was full.
On the way home over a distance of 400 miles, the vehicle averaged 33.5 mpg on mostly freeway driving at 60-65 mph using cruise control but some smaller roads with a few towns to go through, down from the normal 40 mpg that I have typically measured on long trips.
That is a reduction of about 16% from the 40 mpg, which is close to the range of 20-50% reported by others.
Answer: Consider how many pounds of force (which is proportional to horsepower) is required to move the roof top box through the air at cruising speed.  Assuming for now that the additional drag is the same for all vehicles (it probably isn't), the box will increase the fuel consumption (in gallons per mile or gallons per hour) at a given speed by the same amount for all vehicles regardless of their size or fuel economy.  While the additional amount of fuel is the same, the increase in consumption will appear as a larger absolute change to gas mileage for an economical car than for a gas hog, but it's the same amount of extra fuel and thus the same extra cost (for problems like this it's easier to calculate the European way, consumption per unit distance).  In real life I expect a car design that is optimized for low drag will experience a drag increase larger than that of the box itself because the box interferes more with the car's air flow than it would with a vehicle that has a higher drag coefficient, but this gives us a place to start.
Now for some numbers.  Last year we made two cross country trips  ~ 20,000mi in a 6cyl. 2006 Subaru Outback wagon mostly on interstates at 70-80mph, AC on.  We carried a somewhat streamlined Thule box of ~ 3 ft width for on the first trip and no box on the second.  We kept careful mileage records (total consumption/miles for each trip), calculating ~ 23mpg with the box and ~26mpg without it.  Convert this to the difference in gallons per mile and you can apply it to to obtain a rough extimate for how a box would affect your car.  Assuming that a gas engine consumes ~ .45 pounds of fuel per horsepower-hour one can calculate the power needed to push the box.  (Diesels might realize ~ 0.40 lb/hp-hr.)
In comparison, we once drove cross country with a 3ft. wide 16ft. canoe atop a minivan - mileage was unchanged indicating that the canoe's improvement of the vehicle's drag coefficient just offset the additional frontal area of the canoe.
Answer: Two road bikes on my car roof increased the fuel used by about 50% on a country trip I frequently go on. Normally, I get around 1200km (up to 1350km) range with my 2009 Ford Mondeo 2.0 diesel hatchback. However, I only traveled 810km before having to refuel. Very disappointing but still worth it. Fuel cost was about $90 instead of $60.
Comment: 810/1200 is 67.5%. If your measurements are correct, you are actually getting an increase fuel consumption of 32.5% not 50%.
Answer: I have a diesel car with 2L engine, when I drive with 4 bikes on the roof my fuel increases from 6L/100Km to 8.5L/100Km at around 110-120 km/h cruising speed.
I have find out is better to avoid highways so I can go slower in order to decrease the fuel consumption and temptations to accelerate and drive at a higher speed :)
For example driving with 100 km/h will decrease my fuel consumption with 4 bikes on the roof to 7L/100Km
Answer: I've used a Packasport 60 on my 2012 Acura MDX on a stock roof rack since I purchased it, so 8 years of use now. The Packasport looks pretty aerodynamic, and compared with other's results, perhaps it is. Based on my measurements the drag reduces my U.S. MPG by 20% when empty when I am doing about 50% freeway travel. If I am only traveling at slower speeds, around town, it reduces my MPG by about 12-15%. The Packasport has seen a lot of use and is now oxidized and cracked on top, so not as smooth a surface as originally purchased. This hasn't translated into a significant difference in MPG reduction. Without the Packasport I get about 16 MPG around town and 22 MPG on the freeway. The first four years I left the Packasport on all the time, but now take it off when not in use.
I also have a hitch carrier that folds up. When folded up it reduces my gas mileage by ~3%, which I mostly attribute to its 60 lb weight. When folded down it reduces my gas mileage by ~4%.
In the coming year I plan to upgrade to a Lexus 450 (hybrid) for the better gas mileage and will probably only use the hitch carrier.


Is there a penalty to ride checks on invisible mounts?

Question: Assuming I'm correct to say that if I'm invisible and my mount is also invisible (separate spells in this case) then I can't see my mount, do I get a penalty to ride checks for that mount?
Comment: Because being able to address specifics is often more useful, do you know yet what kind of mount?
Comment: The mount happens to be an Eidolon. Flying, 6 legs, large.
Answer: No, there isn't
The invisible condition applies the following:

Invisible creatures are visually undetectable. An invisible creature gains a +2 bonus on attack rolls against sighted opponents, and ignores its opponents' Dexterity bonuses to AC (if any).

The penalties of being invisible are all applied against attackers, it doesn't affect the invisible creature in any way, or seems to affect her own dexterity or strength based checks in any way, which includes the Ride skill.
Not only that, but an invisible creature can be found by trying to touch it, as described under the Invisibility special ability. Since you are, you know, mounted on the creature, you are always touching it, and no other checks should be necessary.
Finally, the rules for Mounted Combat also have no mention of invisible mounts being an issue.


What is the term for two kanjis, that when written in the reverse order, have the same meaning?

Question: What is the term for two kanjis, that when written in the reverse order, have the same meaning? For example, "northeast". I have seen this situation occasionally.
Comment: I found a interesting page. https://oshiete.goo.ne.jp/qa/7266471.html
Comment: There's a similar list also on this site bacause OP asked about this before. https://japanese.stackexchange.com/q/44242/5010
Comment: It'd be useful if you could give some examples.  Even with 東北 and 北東, I'm not sure they're used interchangeably.  I might be wrong, but 東北 seems to be used in names of places, but 北東 I haven't seen that much and it might be used more for the cardinal direction.  Not entirely sure.  Nevertheless, if there are other examples you have in mind, it might be useful to post them.  They may or may not be entirely interchangeable.
Comment: @naruto, this question asks about two identical kanji's. My other question asks about two kanji compounds.
Answer: There is no widely-known specific term for this.
There is a website maintained by a Japanese amateur kanji fan, where you can find the list of kanji compounds that makes sense when written in the reverse order (not necessarily the same meaning). The owner of the site calls such words 反対語(はんたいご, literally "opposite word").  But normally 反対語 means antonyms such as 男/女 and 大きい/小さい, and he owner admits this is his own definition of 反対語 which is usable only on his site. He just could not find a better specific word, and ended up borrowing the word 反対語 for his own purpose.
Yoshinori Sakai, another amateur kanji researcher, published a book called 可逆語を探す in 2004, where 可逆語(かぎゃくご, literally "reversible word") appears to be defined as a kanji compound that still makes sense when written in reverse order (again, not necessarily the same or similar meaning). But apparently almost no one have accepted this term after this book.
Comment: BTW, if I had to coin a new term for this, perhaps I would use 可換語 or 可換熟語. 可換 ("commutative") is a mathematical term that exactly means "the meaning is unchanged when written in reverse". For example `a + b` is the same as `b + a` because the addition is 可換. No one seem to have used this term, though.


500 error after dragging joomla website out of subdirectory

Question: I recently dragged a website I built with joomla out of a subdirectory and now the whole website just shows a 500 internal error, can't even log into the backend.  I've already tried changing the log and tmp path variables in the configuration.php file with no luck.  any help as to what could be causing this?
Answer: You haven't specified a Joomla! version but this is our current check list for migrating a Joomla! 2.5.x websites to a live location:

fix the configuration.php file settings for tmp & log directories.
Clean out the cache directories
check the permissions on:

.htaccess
index.php and /administrator/index.php
make sure folders are 755 and files 644 or lower

We do these steps on any move not just ones where we end up with a server error.
If those steps don't rectify (usually do for 99% of 500 errors) check the Apache error log to see if there are any clues to the root cause of the problem.
If you find something in the log you're not clear on add it to your question so people can provide further help.
Answer: I also have the same issue on my site backend. Finally I solved it.
Add these lines to /etc/httpd/conf.d/mod_secuirity.conf
<IfModule mod_security2.c>
SecRuleEngine Off
</IfModule>

Save it and restart apache. It works fine for me.
Adding these lines disable mod_secuirity engine off. I don't know if it causes secuirity problems in future.
Answer: When you do a backup of the site while it's in the old place and unpack with the script in the new place, the userrights are good to go.


How to evaluate the performance of open source solver?

Question: I am looking for a reliable open source solver to solve LP and MILP (with a few thousand variables). How can I evaluate the performance of a given solver for a particular use case?
Answer: The pitfall is to only focus on performance, will ignoring scalability, maintenance, integration and reliability. Some of these are easier to measure than others:

Performance: if I give 2 constraint solvers a - for example a VRP - dataset with 100 visits, which one is better after 5 minutes. See Marco's answer on this question and my blog post on benchmarking.
Scalability: if I give a constraint solver 3 VRP datasets, one with 100 visits, one with 1000 and one with 10 000 visits, for 5 minutes each. How does it scale up? Don't just focus on solution quality, also look at memory consumption.
Maintenance: How easy is it to write a constraint? How easy is it to hire juniors and train them to write constraints? Most business constraints change often. Some even completely pivot their business problem.
Integration: How easy does it integrate with other Java/C++/Python/Kotlin/Scala/... libraries. Can you reuse an existing date & time API (just watch this video why you too will fail at writing your own)? Is available in the library repository (Maven Central / Ruby Gems / Nuget / ...)?
Reliability: Does it fail-fast (or pretend nothing is wrong when things go very wrong)? Does it eat exceptions? Does debug or even trace logging show you what's going on inside the black box?

And that's just the tip of the iceberg. See also my slides on What makes an open source project mature? which covers fun topics such as which licenses are open source ok to build your proprietary business on and which are not.
Comment: I liked the slides, thanks. Do you have some references for the claim that BSD & MIT are widely accepted, while EPL & MPL are disliked by legal departments?
Comment: No, just personal experience I am afraid. Note that EPL & MPL are disliked by *some* legal departments, but those aren't the majority. Same for LGPL. It doesn't make much sense to me though. The far majority do ban *import statements* to GPL libs (to avoid having to release as GPL themselves, which does make sense to me).
Comment: Thanks for the info nonetheless. Most of the software I use (as dependencies) is MIT licensed, so I should be future proof for potential commerical ventures. The exception being COIN OR solvers that are often EPL licensed.
Comment: Yes, the survivors usually use non-exotic licenses (including MIT, ASL & EPL) or have long since switched. When I started OptaPlanner in 2006, it had no license (it was very amateuristic at the time - things have changed a lot) and I ended up with ASL (Apache Software License) in 2007 due following the practices of other successful open source projects. In hindsight, I got lucky, it was the best choice :) ASL is MIT/BSD with patent protection for users - and it also has trademark (= reputation) abuse protection for the authors/community.
Answer: For the evaluation of several solvers you need

several solvers
a testset of instances
a performance measure

Several solvers you probably already have in mind. The testset of instances is a bit tricky, because ideally, this is a not too small, not too large, not trivial, not too hard, still representative set of instances (that is, LPs or MIPs) that you will later see when solving actual instances. There are several ideas how to choose such a testset, I think the MIPLIB2010 paper is still a very good reference for this. Then you run your solvers on the testset, gather the results, and plot them in a way that you can interpret them. For performance (mainly: runtime to optimality, or runtime to a "good" solution) I would use performance profiles as described by Dolan and More. They are kind of an industry standard in the optimization community.
Comment: On performance profiles the note of [Gould & Scott](https://doi.org/10.1145/2950048) is useful, which shows that relative performance has to judged carefully.
Answer: If you're just trying to "evaluate performance" to decide what to use, then avoid LP_SOLVE and GLPK (and the results above are also indicative of their LP performance) and the solution time for LPs (and MIPs, so long as they aren't really nasty) won't be an issue. I suggest Clp/HiGHS for LP and HiGHS/SCIP for MIP.
Comment: GLPK has the advantage that it's open-source (while SCIP is not) and that it can be customized easily with callbacks (which is more difficult with CBC?).
Comment: HiGHS is so much better than GLPK and CBC, and soon will have callbacks as well
Answer: Meindl and Templ published the paper Analysis of commercial and free and open source
solvers for linear optimization problems in 2012 in which they investigate the running times and solving percentages of various solvers. The main table is replicated below. \begin{array}{cr}\hline\sf{solver}&\sf{running\,time}&\sf{instances\,solved}&\sf{solved}\,(\%)\\\hline\sf CBC&10.20&41&47.13\\\sf{CPLEX}&1.45&73&83.91\\\sf{GLPK}&22.11&3&3.45\\\sf{GUROBI}&1.00&77&88.51\\\sf{LP\text{_}SOLVE}&19.40&5&5.75\\\sf{SCIP\,\text{-}\,C}&3.76&63&72.41\\\sf{SCIP\,\text{-}\,L}&6.40&52&59.77\\\sf{SCIP\,\text{-}\,S}&5.33&57&65.52\\\sf{XPRESS}&1.29&74&85.06\\\hline\end{array}

The following data are based on data from the 9th of January of 2012. The following solvers have been used in the test on PC with an Intel Xeon X5680 processor with 2 x 6 cores, 32 gigabytes of RAM on a Linux 64-bit operating system. A total of 9 different solvers were compared using a single thread.

You can thus try to replicate some of the analysis used in the paper where possible.

 Reference
 [1] Meindl, B., Templ, M. (2012). Analysis of commercial and free and open source
solvers for linear optimization problems. Technische Universität Vienna, Austria. Available from http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.455.3926&rep=rep1&type=pdf. [Accessed 5 July 2019].
Comment: Too bad they didn't use geometric mean time instead.
Comment: These results are now 10 years old, so don't include HiGHS or newer commercial solvers. Get proper up-to-date benchmark results from Mittelmann


I can't open DVDs in VLC whenever I suspend my system, why?

Question: I know there are a lot of similar questions out there, so I hope not to get the same answer I've already read a couple times.
I know that DCD playback does not work with stock VLC; you have to install the restricted extras. so far so good, I did that and everything works fine.
But: I tend to suspend my computer, rather than fully shutting it down, because I don't like waiting that much. I also use a program to do timed suspends (qshutdown), so I can fall asleep watching a DVD and not have to worry about a running computer.
You maybe wondering why I'm telling this? here you are: almost every time, I wake my computer from suspend, I can't open DVDs in VLC (it works, if I open it without DVD menus, but then it crashes somewhere in the middle of the film). Is there a known solution to it?
Answer: Okay, someone posted the answer on Google Plus.
Micah Green (https://plus.google.com/u/0/102136182668884097283/posts) suggested that you install libdvdcss.
Tim Cummings (https://plus.google.com/u/0/104389497239909407158/posts) says that hibernating and suspending can cause odd behavior like this.


check quota inside debian openvz vps

Question: How I can check the user quota inside a debian openvz vps ?
The user's mail quota looks wrong; I have this error:
procmail: Quota exceeded while writing "/xxxx/Maildir/tmp/xxxxxxxxxx.com"
but the user quota looks under his limit.
Answer: Check your diskspace and inodes inside the VPS:
vzctl exec  ps -f # for diskspace
vzctl exec  ps -i # for inode usage
In case some of them are out of boundary correct them;
vzctl set  --diskinodes [minvalue]:[maxvalue] --save
vzctl set  --diskspace [min]GB:[max]GB --save

check quota inside debian openvz vps


How do you e-mail a webpage to yourself?

Question: Is it possible to e-mail a webpage to e-mail address. I dont mean the link of a page. I mean the actual webpage in html forms so that the webpage can be viewed in an e-mail.
Comment: Did a Google search and can able to find a lot like this :)
Answer: In IE8 : Page -> Send Page by Email ...
Firefox : Use the add-on Send Page By Email.
Some of these might not work, depending on your mixture of browser/mail-client.
Answer: When you use Microsoft Outlook 2000, Microsoft Outlook 2002, or Microsoft Office Outlook 2003 with Microsoft Internet Explorer, you can send a viewable Web page with active links to others who use Outlook, Microsoft Outlook Express, or other HTML-aware e-mail programs.


Common expressions of "thank you" in a formal setting

Question: What are common ways to say "Thank you very, very much" in a formal or business setting? I am interested in both, phrases for a written letter, and formal ways to express "thank you" in talking. Are they different?
Comment: 1) As it stands, this is a translation question which does not show prior research effort and would thus be closed. To avoid this and to get a satisfying answer, please clarify why a dictionary did not provide a satisfying answer (see also [this guide](http://meta.german.stackexchange.com/q/628/2594). 2) Can you somewhat clarify the desired intensity of thanking? The title of your questions seems to ask for regular thanks; "very, very" seems to be asking for something more emphasised or overly thankful.
Comment: @Wrzlprmft: edited Q to narrow it a bit down.
Answer: There is not the answer, but I think the most common and formal one would be
Vielen herzlichen Dank

Answer: To thank in a regular way, in Germany, you say

Dankeschön!

while in Austria you say

Danke sehr!

But you can use both phrases in both countries.
For a more intense way to thank, you can say in both countries:

Vielen, vielen Dank

or

Ich danke vielmals!

Sadly, I dont know how they thank in Switzerland, but I am sure, you will be understood also, if you use the phrases above.
Comment: In Switzerland, you'd probably hear "Danke vielmal!" in most cases, but there are regional variatons. And "Dankeschön!" is also used a lot, from my experience.
Answer: The "best way" depends on the context in which it is used. Without any further details I would say:
Vielen, vielen Dank.

If it should be a little more personal:
Vielen lieben Dank.

Comment: What's the difference between 'lieben' and 'hezlichen'?

Thanks a ton. I had it as wrong as 'Vielen Dank, dass Sie sehr, sehr viel' (Google Translate), haha
Comment: @ST42: "Lieben Dank" is more personal/intimate than "herzlichen Dank". The latter is appropriate for a business relationship, too.
Answer: To emphasize the very, you could say

(Meinen) besten Dank.

To add a more personal touch, herzlichen instead of besten works fine, in both cases you express above-average gratitude.
Answer: Supplementary answer: For business settings I would suggest a longer sentence, like

Ich möchte mich bei Ihnen herzlichst bedanken.

or

Ich möchte mich bei Ihnen für Ihr/e/n random positive attribute sehr herzlich bedanken.
Answer: I would go with

Vielen, vielen Dank

or

Ich danke Ihnen sehr

which expresses your special gratitude because you explicitly say that it is you who is thanking the other.
However... I'm not sure that it is at all common to thank people a lot in business relations in Germany. It would be a weird bit too personal for my taste to express deep feelings of gratitude, especially if you say the circumstances are rather formal. You would rather emphasize how happy you are about the great opportunities you gain by this deal, or how much this decision has helped you to reach your goals.
Comment: True - I was assuming the setting were a face-to-face conversation, during a meeting or the like, because I imagined the big thanks to be given as a more personal note in an otherwise formal setting. In a speech, in official negotiations or even written word, I would definitely not use that. "Vielen, vielen Dank" is as personal as I would go, if you will.
Comment: If used in a formal setting, "vielen, vielen Dank" would sound immature to me, especially in writing. But I am an old man.
Comment: I agree with that.
Answer: Usually, Germans tend to express emotions in not too many words, so a simple

Vielen Dank!

would be the most common way to say that. And that is perfectly fine to do so, there is no need to do it more bloomy.
I saw the difference when having a friend from the U.S. visiting me here and I just proposed to do a little show-around, and she used words like awesome and thank you sooo very much - if a German had uttered such words, I'd think he's kidding me, but with an American that means just thank you.
Nevertheless, Germans also had great poets and the language is able to express it in a more complex way, such as

Ich möchte Ihnen meinen allergrößten Dank zum Ausdruck bringen!

But one wouldn't use it in normal business talk, even in a formal one.
Answer:
Vielen Dank

or

Ich danke Ihnen

are the best ways so far
Comment: You know that for a fact? Try writing "ich danke ihnen" in an application correspondence.


Best way to add filtering for the data in grid ? dynamic filter fields or filter for each column separatly?

Question: How I can add 'Multiple' filters on my page for the data in the grid (grid is having 10 columns and I want to add filter for all the columns) which will be more obvious and easy to use for the user (i.e. without making them confuse) ? I have two options in mind.
First one is to add a dropdown list (having all the columns' names in it) and a text box (where user will type the value to filter the data with respect to the selected column name in the dropdown list).Then I'll add a '+' icon button at right to add another filter (clicking the '+' button will add another dropdown and a text box for multiple filtering) so that user can add filters upto 10.
The other option to implement this is to add a permanent text box on top of the data columns in grid for every column.
Which option will be more suitable and why ? or tell me if there any better way to implement multiple filtering.
I'll be thankful for your valuable suggesstions.
Answer: I have seen both implementations and I am all for the second option. The reason is simply because it provides a better spatial mapping between the filter definition and the data it is applied on.
One major problem of filtered grids is that the active filters are not obvious enough. Make sure you convey to the user that the data is filtered.
Another suggestion is to try to avoid free entry text boxes if possible. I favor a button that opens a popup (similar to a dropdown) where you have more space to place more usable controls like combo boxes, radio buttons, drop downs, sliders and so on. This make the filter definition process easier.


iPhone 6s, Jailbroken Stuck in Recovery Loop

Question: I jailbroke my phone and one day I accidentally dropped it in some water.
The iPhone around an hour or two later while charging decided to not charge any more saying that this cable is not supported by Apple (but it was), and didn't charge. I tried different cables and power sources, none of which worked.
I then proceeded to panic, and reset my phone in the settings app. The phone began to reset and then got stuck after a while on a full progress bar, so I did a reboot of the device, and now it is stuck on a boot.
It starts normal, than a progress bar appears, which goes about 1/5th of the way and then the phone reboots to a normal Apple logo, and then it turns a bit orange (F.lux from the jailbreak), and then just stays like that forever.
I was wondering if there is a way to enter DFU mode or recovery mode, without the phone being plugged into anything and then reset the device so I can go to Apple, or have I lost this phone forever?
Also, I have tried cleaning out the charging pins multiple times.
Comment: Sorry I just realized I don't Think that the apple logo turns orange when booting but is there still a way.
Answer: I thought this is not issue of jailbreaking. Please try to restore with Factory Settings or iTunes.


Is it possible to have a character who does not develop?

Question: Is it possible to write a story with a single character and no development of that character at all?
Comment: A classic example is Sherlock Holmes, who generally solves the case brilliantly and continues entirely unaffected. A story whose focus is on plot or setting might not need character development at all; character development might actually distract from the focus. But it depends on so much, particularly on _what it is that you're trying to do_, that I really can't say much beyond "yes, it can be done."
Comment: @Standback ACD's Sherlock Holmes does *not* lack character development. The man who meets Dr. Watson in *The Sign of Four* is not capable of the emotional outburst in "The Adventure of the Three Garridebs" when Watson is injured and Holmes fears for his life. And if he never changed or developed, he wouldn't be willing to settle down and retire to Sussex to keep bees; he'd continue to try to solve crimes from Baker Street regardless of age or infirmity. He may not change *much*, but he changes.
Comment: @LaurenIpsum: My intention wasn't that Holmes _never_ has character development, but that many of his individual stories don't have any character development.
Comment: @LaurenIpsum Definitely related, but I think this question contains a different enough shade of meaning to stand on its own.
Comment: @Standback Yes, that I'll grant you.
Comment: Related, nearly a duplicate: http://writers.stackexchange.com/questions/2920/can-a-book-be-written-without-an-antagonist
Comment: Yes, it's possible. Is this something you _want_ to do? Is this a criticism you're getting? Are you asking out of sheer curiosity?
Comment: A character who recieves no development is called a "static character" and is usually reserved for secondary characters who are meant to be the same personality.  Comedy and many Cartoons also use static characters as the point isn't to learn a lesson, but to make jokes related to the flaws (i.e. Yosemite Sam is famous for being a western outlaw, but also fitting as outlaws in other settings including a pirate, a black knight, and an evil Arab.  Yet he never stops being "Sam."  Similarly Bugs Bunny never changes between the eras or as a result of his stories.).
Comment: Brandon Sanderson refers to major characters with no development as "Iconic". He discusses this idea in depth in [this episode of Writing Excuses](https://writingexcuses.com/2018/07/22/13-29-iconic-heroes/).
Answer: You can always have a character who doesn't develop; flat Disney villains come to mind. But the flat character is generally in opposition to the hero/ine, who does develop.
So the question is, why would you write such a story? What could possibly happen in it? If you have one character, period, and that character doesn't develop, what is that person doing?
Answer: The TV show "Seinfeld" is an example of a show where the characters didn't develop. They never learn anything about themselves and this was a source of humor in the show. Or at least it must have been for the people who liked it (and there was a lot of them), personally I never really got into it.
I think also some of Samuel Beckett's work would have one or two characters and little or no character development, some of it is also comic, and indeed absurd.
Comment: This is actually a great example. Maybe it's one of the reasons I couldn't stand the show either; you had four horrible people who never got any less horrible.
Comment: Comedy is maybe the only genre where static characters can work. However, a sitcom like Seinfeld is mostly about interaction between characters, and the question was about a story without character interaction.
Answer: Is it possible? Probably. It may depend on the definition of "character development". I was just looking for a definition and didn't find one in 30 seconds, but it's normally understood to mean (a) revealing the nature of a character to the reader, and/or (b) a character growing and changing over the course of the story.
By definition (a), if you write, "Bob walked into the room", you have told us several things about the character: He is named "Bob". He is capable of walking. He has some reason for wanting to be in this room. Okay, trivial things, but you have begun the process of character development. It's hard to imagine a story where you literally tell the reader absolutely nothing about any of the characters, even indirectly.
It's a little more plausible by definition (b). I suppose you could imagine a story where the characters learn nothing and do not change in any way. But at the very least, you would think that SOMETHING must happen to the characters in the course of the story, so if nothing else they have gained experience. Even if you do not spell out how the character's react to these experiences, the reader is likely to draw inferences.
Perhaps you could be more specific about what you have in mind.
Comment: Maybe a story about an Alzheimer's decease patient?
Comment: @celtschk I suppose you could write a story about a character in a coma who is unaware of anything happening around him and so cannot react in any way. But that sounds like a pretty boring story ... unless the REAL story is about the other characters who come and go from his hospital room.
Comment: Another thought years after that post: You certainly could have a story where the character goes through some experience, and the whole point of the ending is that despite this experience, he has learned nothing. Like, the politician takes bribes, he is almost caught, gets away by some lucky break, a friend tells him that he really needs to straighten up because next time he might not get away with it ... and then the story ends with him taking another bribe.
Answer: It definitely is possible. If you don't want them to grow, then you should probably have another character who does grow. A reader finds a character growing from one extreme to another interesting.
If a character does not grow at all, you may want to make them close to, but not perfect. If it is the protagonist who does not grow, you want them to be at least a little noble, honorable, and possibly even have a past where did grow, but now are done growing. If it is the antagonist, then you should probably make them mean, malicious, and all the key elements of an antagonist.
Writing a story is a journey in itself, but what your characters do is up to you. If they don't grow at all, I would suggest you make sure their life is filled with challenges so that way it still is interesting to see how they handle each challenge.
Answer: It is possible. How, I know not, but it is possible. I once wrote a story that was literally a narration of events with no character, and the community (it was a fan fiction) really liked it. I still don't know how that happened.
A character did appear later on, but there was no character development. The closest it got was when the character almost sacrificed himself so someone could escape, but that event had no impact on anything else whatsoever. The character never changed.
Needless to say, that was written before I knew anything about development.
Comment: I'm just curious, but would you be willing to link to this story?
Comment: Certainly. I would prefer not to put it here though. Is there a private messaging system on this site? I can't seem to find one. (Just be aware that I did not know how to write when I wrote it, and there are a LOT of things wrong with it.
Comment: There's no private messaging system on Stack Exchange, but you can contact me [here](http://neilfein.com/contact-me/).
Answer: Normally, when the main character remains static, that character is actually a catalyst character and the world or characters around them are the true protagonists. A popular example is Ferris Bueller's Day Off. Ferris Bueller may be the titular character, but it is more or less agreed that his best friend Cameron is the real protagonist, Ferris merely gives Cameron an impetus to change.
This may be an interesting route to try if you were to write a story with a single unchanging character!
Some development must occur to have a successful story, even if it's a change in the audience's understanding rather than one inside of the story itself. Otherwise, there would be no point in consuming it, it'd be the literary equivalent of empty calories.
Answer: Anything is possible in writing.
There may be quality issues though.
Wait, let me get this straight.
You want to write a single story with one static character total?
You could, but I can only think of one other story that a single character and thats Hatchet by Gary Paulsen and that was a dynamic character.
Answer: I am actually adding a second answer based on something @user16583 mentioned.
In some long-running comic strips, characters don't age or change. Strips like FoxTrot and Sally Forth occasionally make sly meta-jokes referencing the idea that the kids in the strip have been 10 or 12 for decades. Beetle Bailey has been doing the same thing for 70 years.
But even really long-running strips have some changes: The cast of Peanuts expanded, Blondie has gotten a job, there have been new platoon members and sexual harassment training at Camp Swampy.
So while you might be able to pull this off with a series of short stories (like Jeeves & Wooster, perhaps) or a graphic novel, particularly if the stories are meant to be funny, I think you'd be hard-pressed to make it work with drama.
Answer: In many books on writing, a story is defined as the emotional journey (change) of the protagonist. Plot is the physical journey.
If you buy into that (as I do), then you need change in order to have a story.
Answer: This summary of K M Weiland's Creating Character Arcs: The Masterful Author's Guide to Uniting Story Structure, Plot, and Character Development discusses examples of her observation that the protagonist's character development often involves their discovering they believed a big lie, and is avoided if they consistently believe a big truth and can influence others to adopt it, even unintentionally. The two Paddington films are universally critically acclaimed examples of the latter approach.
An author worried their protagonist doesn't develop should review how others consequently develop around them, and decide whether (and if so how) they want to change the story so the protagonist develops as well. I've written at least one work in which, while the protagonist's influence in their world is largely characterized by how others develop because of them, they develop as well but in a dissimilar way.


Contact Summary Hook Implementation

Question: I am trying to add contact created date in contact summary. I am sure that https://docs.civicrm.org/dev/en/latest/hooks/hook_civicrm_summary/ helps the requirement. But I'm not getting how to implement this hook.Any help please?
Answer: As already pointed out, the created date is shown on the summary anyway - but since your question is more about using hook_civicrm_summary(), here's an simple example to add the date above the existing summary content:
function demo_civicrm_summary($contactID, &$content, &$contentPlacement) {
  // Lookup 'created_date' for the specified contact
  $dateCreated = civicrm_api3('Contact', 'getValue', array(
    'id' => $contactID,
    'return' => 'created_date',
  ));

  // Set $content to what we want to display
  // Can add html with classes for formatting ...
  $content = 'Date created: ' . $dateCreated;

  // Set $contentPlacement to specify where our content is displayed.
  // The default if we don't set this is to display below the existing summary
  $contentPlacement = CRM_Utils_Hook::SUMMARY_ABOVE;
}

Answer: The contact created date does show up on Contact Summary page at the bottom of the summary page

If you want as a field to show in summary section then i feel you can use civicrm_summary hook but it would to be very difficult to manipulate where to insert a section in $content as it would be pure html. I would use Buildform and/or Page run hook to add field with some JS to place the field in the page/form.
HTH
Pradeep
Comment: I expect you know the data is in civicrm_contact.created_date field but since no one has mentioned that i thought i should state the obvious

Contact Summary Hook Implementation


How do we promote our site?

Question: One of the big 7 questions.

One sugestion per answer, please
Answer: Comments on off-topic questions on Stack Overflow. There are lots of questions that pop up on Stack Overflow that would be better suited here. Using comments as a vehicle to promote this might be a good way to funnel traffic to its appropriate place in lieu of having a Migrate to Programmers close option.
Answer: Word of mouth. I'm at school now, but I'm planning on telling everyone I know who might be interested in this to check it out when it enters public beta. I'll probably also shoot an email to some old coworkers of mine, Tweet interesting questions, etc.
Answer: "Like/Share" type links for various social networks? I have a many people on social networks that I would like to spread this to.
This probably exists somewhere, but I haven't been able to find it
Answer: SEO - ask good questions and give better than wikipedia answers that are relevant and likely to get linked up to lot's of blogs.
If you really want to advertise the site, you've got to make the internet better.
Of course this is just a ruse to put Mr. Rock Hard Awesome through Stanford.  But I don't care, it's fun.
Comment: +1 The best way to promote this site is just to *use it*, and let Google do its job.

How do we promote our site?


Type of Navier-Stokes equation

Question: What type equation Navier-Stokes is: Elliptic, parabolic, or hyperbolic? Should it give always the same answer no matter what is the initial condition? How these statements could be proved?
Comment: http://physics.stackexchange.com/questions/62135/what-type-of-pde-are-navier-stokes-equations-and-schrodinger-equation
Answer: The question assumes that there is a strict delineation between equations, but there isn't. On paper, of course, the Navier-Stokes equations have a parabolic character because there is a non-zero diffusion term. But, in reality, we say that equations are "hyperbolic" when we mean that they are advection dominated, and "parabolic" when they are diffusion dominated, and the Navier-Stokes equations can be either depending on whether your Reynolds number is large or small.
I have tried to make this point in lecture #26 at http://www.math.tamu.edu/~bangerth/videos.html in more detail.
Comment: And in the limits: for negligible viscosity you get the Euler equations which are purely hyperbolic, for negligible advection (large viscosity) you get Stokes flow which is elliptic.
Comment: @WolfgangBangerth The compressible Euler equations are purely hyperbolic (they are diagonalizable and the eigenvalues are all real). Incompressibility is a further assumption and yes, it complicates things a bit. Conversely, It's my understanding that the Stokes equations are purely elliptic and there is no time dependence aside from the possibility of time-dependent boundary conditions. There is no memory in the system and information propagates instantly through the entire domain, the hallmark of an elliptic PDE.
Comment: Wolfgang probably mentions this in his lecture, but I'd add that a standard general approach to numerically solving NS is treating the advection operator as hyperbolic, the diffusion as elliptic, and the time stepping as parabolic.
Comment: @DougLipinski: Yes, basically. Though it's not that simple: in the large viscosity case, you get the time dependent Stokes equations which are, at best, parabolic. But, if you applied the strict conditions based on the operator involved, it's not actually that simple any more because you have a system of equations and it's not so obvious whether the eigenvalues of the system operator actually satisfy the conditions for parabolic-ness. In the limit of vanishing viscosity, it's the same: it doesn't quite fit the categories because there is no pressure time derivative.

Type of Navier-Stokes equation


Is a LATCH booster seat used without LATCH any less safe than a LATCH-less booster seat?

Question: We have the Graco AFFIX Backless Booster Car Seat with Latch System, but our new babysitter's car does not have LATCH.  Would there be any difference between using this seat without LATCH (just with the seatbelt) and buying a LATCH-less booster seat?
Comment: How old is the child that will be riding in the car?
Comment: Almost 5 years old
Comment: Our 5 year old rides in a belt only booster now. I don't think it would matter much either way for you
Answer: Anchors for booster seats are only for convenience, not for safety.
he LATCH system, as mandated in US vehicles from 2002 onward, supports a total combined weight of both child and seat of no more than 65 pounds. I found this information on Consumer Reports.
Depending on the weight of your car seat or booster seat, this may mean the LATCH system only supports children weighing anywhere from 32-50 pounds. In these cases, it's necessarily safer to use the seat belts to secure the seat, rather than the LATCH system.
The reason LATCH was developed was not because it is inherently safer, but because it's inherently easier to secure the seats properly.
Securing seats properly with the seat belt straps is more difficult, so more care must be taken in doing so. However, seat belts do not have the surprisingly low maximum supported weight that LATCH systems do. Seat belts are designed to safely secure adult passengers of various weights.
Booster seats that only use the seat belt to secure the child, and don't secure the seat, gain no additional safety benefit from the LATCH system. It's there mainly for convenience: the child can get in the seat themselves without it shifting and it doesn't become "free" when not in use. Children in this types of seats are more likely to outgrow or already by over the weight limits of LATCH systems.
If the booster seat is not in use, it should be anchored with the LATCH system or stored in a safe area, in order to prevent it from becoming a hazard during a car accident.
Comment: no offense intended: I upvoted your answer before. My comment was just a clarification. With your edit, I can/will remove it. Ironically, LATCH for boosters means also more safety for *other passengers* when the seat is *not* occupied as it's held in place (vs. flying around) in case of an accident. Of course you are *supposed* to secure regular boosters when not in use, too, but LATCH does this "automatically".
Answer: With car seats for younger children (infants or toddlers), there are straps which hold the child into the car seat and then an additional system to secure the seat to the car. This used to be with a regular seat belt, but in modern vehicles is more commonly with LATCH. (Having once fed a seat belt through a toddler seat in a car without LATCH, it's quite obvious that the LATCH system was a terrific innovation for its ease of use.)
In contrast, the child is being restrained by the car's seatbelt when sitting in a booster seat.

A booster seat is a firm cushion of foam or plastic that raises the child higher in the car to improve the position and angle of the shoulder belt. Source
Booster seats are a type of child restraint that do not have a five-point harness system, but rather rely on the vehicle seat belt system to keep your child restrained. The booster seat elevates your child so that the vehicle seat belt is positioned properly over your child. Booster seats should be used in the rear vehicle seat with a lap and shoulder seat belt system, never a lap belt-only. Source

(emphasis mine)
The LATCH connection for the seat you have isn't providing any additional restraint -- imagine your child sitting it in without a seatbelt, it's just as easy to fall forward in the case of an accident whether the seat is secured to the car or not.
The key thing is to make sure the booster seat is is used with both a lap and shoulder belt.
I would personally purchase an additional (LATCH-less) booster seat for the babysitter's car, so it's always there and you won't ever have the problem of forgetting to transfer the seat. We actually own four booster seats for two kids, to cover a range of possible transportation situations -- the extra set purchased after one frustrating week where we forgot to transfer seats every single day.
Comment: Thank you.  FWIW, the booster seat is just for the babysitter's car.  We bought it before knowing her car didn't have LATCH.
Comment: If you can exchange it, I'd get a LATCH-less instead just because they're typically cheaper -- but it isn't a giant savings and may not be worth the hassle :)


Ingredients of Root Beer

Question: I want to make root beer, what are the ingredients required to produce that signature flavor?
Answer: The primary ingredient in the root beer flavor is traditionally sassafras root. However, modern root beer uses artificial sassafras flavoring because the US FDA banned safrole, the oil from sassafras root. It is considered a weak carcinogen as well as a List I chemical by the DEA (used in the manufacture of illicit substances).
Beyond sassafras the ingredients vary widely and drastically between manufacturers. The most common include vanilla, wintergreen, cherry/spruce bark, licorice, anise, and many more. A more complete list of root beer ingredients can be found on the wikipedia page.
If you're looking to make your own, I suggest finding a recipe and following it. Given the vast array of ingredients present, you'll have to do a ton of experimentation to stumble upon a suitable flavor without a recipe.
Comment: In the UK, whenever I have had root beer, [sarsaparilla](http://en.wikipedia.org/wiki/Sarsaparilla) has been the primary flavouring ingredient.  I have not encountered the sassafras style due to the health risks most likely, and because the root beer we have I think has a path more directly from the Caribbean, which I believe uses sarsaparilla more.
Answer: I am not a root beer expert, but to me (and a few others, including root beer homebrewers :)) Russian квас / kvass (a fermented rye beverage) is very similar to (family-made) root beer, so I think you might be interested in it too, as the ingredients for kvass might be easier to find in your vicinity.
Kvass variants run from clear and light to dark and heavy with all sorts of additives (usually fruit) possible. People use different kinds of bread, and some people cook or fry the bread first. Most kvass has a little alcohol in it (depending on its age) -- some has more, but usually not so much as to be dangerous if drunk in normal amounts.
A lot of enthusiasts give different recipes, but the usual ingredients are:

(stale) (dark/black) rye bread
water
active dry yeast
sugar or honey
raisins
Answer: Ingredients

1/4 cup sassafras root bark
1/4 cup winter green leaf
2 tablespoons sarsaparilla root
1 tablespoon licorice root
1 tablespoon ginger root
1 tablespoon dandelion root
1 tablespoon hops flowers
1 tablespoon birch bark
1 tablespoon wild cherry tree bark
1 teaspoon juniper berries
1 cinnamon stick
1 cup unrefined cane sugar
1/2 cup ginger bug, fresh whey or 1 packet kefir starter culture

Instructions

Bring two and one-half quarts filtered water to a boil and stir in sassafras, sarsaparilla, wintergreen, licorice, ginger, hops, juniper, birch and wild cherry bark. Reduce the heat to a slow simmer and simmer the roots, berries, barks, leaves and flowers for twenty minutes.
After twenty minutes, turn off the heat and strain the infusion through a fine-mesh sieve or a colander lined with cheesecloth into a pitcher. Stir unrefined cane sugar into the hot infusion until it dissolves and allow it to cool until it reaches blood temperature. Once the sweetened infusion has cooled to blood temperature, stir in the ginger bug or fresh whey and pour into individual bottles (preferably flip-top bottles which are easy enough to find online, leaving at least one inch head space in each bottle.
Allow the root beer to ferment for three to four days at room temperature, then transfer to the refrigerator for an additional two days to age. When you're ready to serve the root beer, be careful as it, like any other fermented beverage, is under pressure due to the accumulation of carbon-dioxide, a byproduct of fermentation. Open it over a sink and note that homemade sodas, like this one, have been known to explode under pressure. Serve over ice

From Nourished Kitchen
Comment: Under most circumstances**, the policies of the site are against specific recipes ... but as I'm actually really impressed with this one ... and the Nourished Kitchen site in general.  ** recreating specific dishes are the exception ... so if someone said that they were specifically trying o re-create [Wild Bill's](https://www.wildbillssoda.com), [Frostie](http://en.wikipedia.org/wiki/Frostie_Root_Beer) or [IBC](http://www.ibcrootbeer.com/), then we get to the specifics of recipes.
Answer: Root Beer Extract + sugar + champagne yeast
You can make your own extract, but I certainly wouldn't go there first.

Ingredients of Root Beer


Would Deathstrike's healing ability be able to save her?

Question: In the second X-Men movie, X2, Wolverine defeats Deathstrike by injecting her with liquid adamantium. Considering that Deathstrike has a healing ability similar to Wolverine's, would she come back to life if all of the [excess] adamantium was removed from her body? If yes, would there be a limited window of opportunity to perform such a procedure successfully?
Answer: This answer is purely conjecture, given the limited amount of information we know about Deathstrike from X2: X-Men United.
Due to the way that the adamantium was injected into her body, it is unlikely that Deathstrike's healing factor would've been able to save her, unless her cells found a way to regenerate a nervous system around the hardened adamantium. Wolverine's adamantium was bonded to his skeleton surgically, the liquid wasn't injected into his body haphazardly, which is how he was able to survive the process.
Additionally, when we last see Deathstrike in the film, she is both submerged and trapped in a tank of water, assuming that the injected adamantium wasn't completely surrounding her lungs, she would also have drown, in addition to any damage the adamantium caused. It is unclear how much lung damage someone with a healing factor can handle before they finally drown.
Deathstrike's best chance for survival would have been an immediate intervention from Magneto, whose power would've allowed him to return the adamantium to its liquid state and remove it from her body.
According to Wikipedia:

Kelly Hu wanted to reprise her role in X-Men: The Last Stand, indicating the she
  survived the fluid adamantium injection by Wolverine, but after Bryan Singer was not on
  the project anymore, she was not on the project anymore either. [source:wikipedia]

However no source is provided, so we can't be sure how accurate this information is. Regardless, we'll probably never know how Bryan Singer had intended for her to survive the adamantium injection.
Answer: It look like she survived, as she come back in X-Men: The Official Game, Chapter One :

In the depths of the base, Wolverine finds Hydra has a familiar agent: Lady Deathstrike, who was able to survive an apparent death in X2 after being pumped full of adamantium.
Answer: It depends totally on how graphic you want to be and how her regeneration is defined.

This version of Lady Deathstrike is not portrayed as a cyborg, but as a brainwashed mutant with regenerative abilities similar to those of Wolverine. This version of Lady Deathstrike also demonstrates superhuman strength in the film, throwing Wolverine across a room with enough force to shatter a concrete wall. The title of "Lady" was not used in her name.

If Deathstrike's regeneration abilities are reputed to be just shy of Logan's in terms of efficiency, then her resurrection could be accomplished in a number of grisly ways:

Physically removing the adamantium from her body. If her powers of regeneration are equally potent, you could simply cut the hunks of now solidified adamantium from her body and let her "return to the living state" much like Logan would.
It would be messy, ugly and unglamorous but certainly possible since such a thing would not stop Logan from regenerating once the same was done to him.
She could also opt for the cellular rejection method of superheroic regeneration. Her body could simply grow behind the now solidified chunks of adamantium until she was reformed with the adamantium outside of her body, the same way evil villains show off their power by expelling the bullets, pushing them from their bodies.

This would take a considerable amount of time, probably be VERY painful, and make for an EXTREMELY pissed off or even insane Deathstrike when she was done. She would certainly only have one thing on her mind after that. Revenge...
Comment: I thought she wasa robot...
Comment: No. She is a flesh and blood being who has been altered in a fashion similar to Wolverine using advanced technology. Check out the link.
Comment: Yeah, in an interview, Kelly Hu once mentioned that if they were going to do comic-accurate Deathstrike, they would have to cast someone like Dwayne 'The Rock' Johnson to get an imposing enough size, especially since just the arms and hands themselves are gigantic in the comics
Answer: Actually, somehow she was able to survive the belly-full-of-dangerous-liquid event. I am unsure how, but the character is seen last not in the tube, but in the classroom with Charles in the final few minutes of the film. She was the student closest to him in the seating arrangement and there were even a few brief seconds with her face on film. I am unsure how she survived, nonetheless she did.
Comment: That's Jubilee


What are the steps I should take to learn Selenium on the side?

Question: I am currently working a full-time job in QA that does not utilize Selenium. However, I am interested in learning about how to use it and wanted to know what steps I should take to gain knowledge of Selenium.
Comment: Are you familiar with coding? and if so how much experience and in what languages?
Comment: yes, I learned Java,C++,C# in school and have used small amount of C#/Java on the job for about a year.
Comment: I also have a small amount of Python experience
Answer: So for me C# was my language of choice, unlike Brandon Garlock suggests I am going to suggest that you don't use selenium IDE(because you know some code). If you know code, even remotely know code I would recommend writing your own scripts; mainly because of the control and reliability you can have, while building your own tests from the ground up. I started with the following youtube video here. Got selenium up and running in visual studio, and then just began playing around with its functionality. Hopefully this helps you in your search.
Comment: Thanks, this definitely helps my search. I'm glad you brought this method up since I'd much rather code than manually record tests.
Comment: Glad I could help, don't forget to mark the answer and up-vote if I answered your question!
Comment: don't have enough rep yet :/
Answer: The Video that DEnumber50 posted is what i used to get everything ready to play around with C# VS and was very helpful.
I would look up BAT(Black Box Automated Testing) Architecture with selenium. Then take a look at the website you wish to test and write down a list of test. It is important to keep your test separate from the Architecture you will be using in your test. It is my opinion that test driven design is the best way to approach the subject so just let the test drive what you need. So for each test write the classes and methods to facilitate the test. There should be no actual code within your test and similarly no NUnit(Program i use to run the test) assertions in the architecture.
Here are some links that i found helpful along the way

https://www.youtube.com/watch?v=cB1DX1LRMEE
https://code.google.com/p/selenium/wiki/PageObjects
https://saucelabs.com/resources/selenium-testing-framework-part-3-putting-it-all-together
https://code.google.com/p/selenium/wiki/PageFactory
http://simpleprogrammer.com/2013/09/28/creating-automated-testing-framework-selenium/
https://www.youtube.com/watch?v=6ueuLVZTDkk
http://blog.fogcreek.com/the-abuse-and-misuse-of-test-automation-interview-with-alan-page/
http://simpleprogrammer.com/?s=framework
http://james-prescott.com/2014/02/01/tutorial-setting-up-selenium-webdriver-visual-studio/
https://anoopjshetty.wordpress.com/2014/05/20/test-automation-framework-in-page-object-pattern-using-c-selenium-specflow-and-nunit/

I am a big fan of simple programmer he had a two hour talk explaining page modeling and automating test responsibly it is in his blog.
Comment: Videos when first starting out but after the first week documentation is king.
Comment: In your experience, have you found videos or documentation to be more effective?
Comment: Great, I suppose it is easier to quick reference docs rather than videos.
Comment: For sure and more detailed/comprehensive.
Answer: The best way to get started with selenium without having a business objective is to look for a website that you use often and ask yourself if there is a way you can automate what you do on that site that can help you on a daily basis.
Once you have a goal download the Selenium IDE plugin for firefox. Record the actions you want to automate. Then you will be able to export the recording to a variety of programming languages.
Now you will have an example tailored to your needs that you can expand on and use as a reference.
Comment: Firefox is the only browser that is available with the plugin.
Comment: Thanks, this is very helpful. Are there similar plugins available for other browsers?
Comment: Using test automation on other people's sites without their express permission is rather rude. They might even think you're a hacker.
Answer: Thanks for all the responses, they have provided great resources. For others interested, I also stumbled upon this website that seems helpful:
https://university.utest.com/automation-tools-selenium-the-basics/
Answer: Copied from my answer on Quora.
Beside having a good plan to learn something, to be successful, one should also be clear about their goals. You should make sure you understand that:

The demand for test automation (and test automation engineer jobs) will only be increase steadily.
Selenium is the way to go for automating end-to-end testing for web applications.

Learning test automation is possible for everyone—remember that even the greatest programmers know nothing about coding initially. You can also check out this energetic article by a manual tester: How I learned to write Selenium scripts in five days.
Now back to the topic.
Maths is not about triangle, ruler, calculator, pencil etc. If you wants to learn Maths, you should learn axioms, theorems, and how to use them to solve the problems. Tools help in the process, but they will not give you knowledge.
So if you want to learn Selenium and to be good at Selenium, put the tools (Selenium, Appium, Sauce Labs etc.) aside and learn test automation first. The concept stays for long, tools change every day. At the starter level you should know:
Types of test automation (it's not only about automate UI actions) - functional testing, load testing, security testing just to name a few.
Benefits and challenges of test automation (hint: it reduces the cost of execution, but test creation and maintenance will be a big loss if done wrong).
How to fit test automation into software development life cycle and available toolchains effectively (otherwise, tests will be executed, but nobody will care about the result).
You can also grab some good books to go deeper - for example:

Agile Testing: A Practical Guide for Testers and Agile Teams - because the mindset will be as necessary as the tools themselves.
Software Test Automation – Effective Use of Test Execution Tools - it's really old but still a great book.
The Just Enough Software Test Automation - it's a great complement to the first one.

And while reading, you can start following some thought leaders on Twitter.
Enter Selenium. All Selenium-based tools, no matter how they are advertised, share the same core issues of Selenium itself. There are challenges that soon will grow bigger alongside with your tests, to the point that will render test automation useless especially if it is done properly. A good understand of Selenium's pros and cons is necessary for you to write tests effectively later.
So the first step is to see how Selenium works. This answer and this article provide good explanation. You can read more at Selenium homepage.
The second step is to experience what you have read in real life, and feel initial benefits as well as the pains. Just pick up any free tool that help you skip through the complicated WebDriver installation and configuration, such as Selenium IDE or Katalon Studio. Tutorials for these tools are often available for beginners, so it will not take a lot of time.
Then, when you feel comfortable with the concept, you can jump into higher-level tutorials with professional problems. If you chose Selenium IDE, follow this excellent tutorial on guru99.net. If you wanted to learn with Katalon Studio, start here. In my opinion Katalon Studio is a very good tool to learn test automation. The good thing about it is that you can switch between beginner mode (point-and-click) and scripting mode (write code) at any time, so that you can learn and verify along the way.
Of course, you can practice and read books at the same time.
After that, you will know what topics/buzzwords you have to Google more.
Comment: Upvoted because of the guru99.net.
Answer: Sauce Labs has good "Bootcamp" using Ruby and WebDriver that is free (but you have to sign up to download). I've done it in spare time and was fun. Lots of example code and an example website.
Answer: Step 1- Start with Introduction to Selenium
Selenium is a free (open-source) mechanized testing suite for web applications that supports cross-program and cross-working framework interoperability. It is very like HP's QuickTest Pro (QTP, presently UFT), just that Selenium centers around mechanizing online applications. Testing done utilizing the Selenium instrument is typically alluded to as Selenium Testing.
Selenium is helpful for testing web applications as it were. Neither work area (programming) testing nor the testing of portable applications is conceivable with Selenium.
A web application is an application program put away on a distant worker that is permitted to get gotten to through an internet browser over the Internet. Numerous sites contain web applications. Any site part that performs capacities for clients qualifies as a web application. Hardly any instances of web applications are:
Google Search Engine
AliExpress
Returning, the testing of web applications done through the Selenium instrument is alluded to as Selenium Testing.
Step 2 - Understanding the Selenium Types*
Selenium isn't only a solitary device yet a set-up of programming, each obliging distinctive testing needs of an association. It has four parts:
Selenium Integrated Development Environment (IDE)
Selenium Remote Control (RC)
Selenium Grid
Selenium WebDriver
Step 3- Selenium IDE Download And Installation Steps
1- Download Selenium IDE from SeleniumHQ
2- Instant Installation of Selenium IDE for Firefox
3- Install Selenium IDE from the command line
Step 4- Start with the Selenium IDE
You can utilize any of the accompanying techniques to begin working with the web UI mechanization expansion.
After the Selenium IDE establishment, there seems a catch on the Firefox toolbar to open the Selenium IDE experiment architect. You can utilize that catch to open the module window and begin composing the test mechanization contents
You can open the Selenium IDE popup window from the fundamental menu of the program. Go to the Developer >> Web Developer >> Selenium IDE menu alternative.
There are two console alternate routes for dispatching the Selenium IDE popup window.
CTRL+Shift+s- It'll open the Selenium IDE popup inside the current program window in a split view.
CTRL+Alt+s- It'll fork another Selenium IDE popup window isolated from the program.