Cannot type "ć" on Hungarian layout

Question: I need help with keyboard layouts. My layout is Hungarian and on Windows I could type ć using AltGr-9 + c which is a c with an acute. However AltGr-9 + Space gives me a single quote (') and AltGr-9 + c gives me this ç a c with a cedilla despite there is an acute printed on key 9. I tried the Hungarian and Hungarian (Standard) layouts in system settings as well, but the others I cannot understand (dead keys/comma/dot... what do these mean?). I didn't notice any problems with any other characters. Thanks in advance for any advice!
Comment: _Comma_ or _dot_ stands for the decimal point on numpad; and _dead keys_ or _eliminate dead keys_ is obviously referred to include dead keys in the layout.
Comment: There are many hungarian keyboards already installed in Ubuntu. Try checking the other layouts?
Comment: It should be bug with the dead key. I just tested **English international** and saw the same problem with _dead acute_ and "c" which behaves like _dead cedilla_.
Comment: This bugreport seems related: https://bugs.launchpad.net/unity/+bug/1079234
Comment: Could you please tell me where can I find info on the meaning of the kb layout names? I ofc know what's 101 or qwertz/qwerty, but what's keys/comma/dead keys? I can ofc try changing layouts randomly, but it would be nice to know.
Answer: Plain text programs
In plain text programs such as Gedit or gnome-terminal, do the following:
Right click your open document or the terminal window >> choose Input Methods from the context menu >> and then choose Simple (instead of the default System (IBus (Intelligent Input Bus))
AltGr + 9 + c will now work as intended.
LibreOffice
In LibreOffice, the AltGr/Compose key sequences work as intended, but you need to add Shift to get to the 3rd level:
AltGr (or Compose) + Shift + 9 + c.
Comment: Thanks for the answer, but pressing AltGr + Shift + 9 immediately gives me the acute character, so I have no chance pressing `c` afterwards.
Comment: I tried it in LibreOffice Writer and it worked fine, which is why I specified that in the answer. I just tried it in Gedit and it's also going straight to acute. I'm not sure yet how these two editors handle it differently. Which editor are you using and will LO Writer work for you? In gedit, I can inset the correct char  with ctrl-shift-u+107
Comment: The bug appears to be in Ibus. The plain text apps, such as gedit and gnome-terminal (these are the only ones I have tested) are running the key presses through Ibus _even when Ibus appears to be off_. Turning off Ibus for real solves the problem. LibreOffice is working correctly with according to AltGr/Compose key sequences. I'm not sure if it's possible to use AltGr+9+c with LO but I'm guessing not.
Comment: Changing the input method did the trick! Thank you!
Answer: Another alternative for inserting this character is to insert its unicode.
To insert a unicode there are two ways:
1st

Press Ctrl+Shift+U, an underlined u appears;
insert the unicode and press space or Enter.

2nd

Press Ctrl+Shift+U and keep holding Ctrl+Shift, the underlined u appears;
insert the unicode and release the keys.

Using Character Map you can find the unicode u+107 for the small letter ć, and u+106 for the capital Ć.

Cannot type "ć" on Hungarian layout


How much should an amateur charge for a portrait session?

Question: I am fairly new to photography and have done a few high-school senior sessions of friends here and there. I have been getting more and more requests to photograph families, seniors, etc. and am starting to spend quite a bit of my spare time doing this. I consider myself an amateur, but am thinking about charging money.
I am wondering what a typical price for a sitting fee is for a senior session or child/family session, and how many images people would expect from these types of sessions.
Comment: Thanks for the explanation. I assumed he was photographing elderly people.
Comment: I think your location plays important role here.
Comment: Probably worth mentioning that "Senior session" (in fact, the term "senior" meaning a high-school student itself) is pretty uniquely American.
Comment: Also, "American" means US citizen, not the whole continent with the 40 different countries.
Comment: See also http://photo.stackexchange.com/questions/7432/how-do-you-determine-how-much-to-ask-for-when-someone-wants-you-to-photograph-a-w (particularly, @Jay Lance Photography's answer, which isn't wedding-specific).
Answer: I don't agree that pricing should only offset your costs.  Photography was a hobby before you started making money with it, so the cost of your equipment isn't exactly an expense of your photography business.
Instead, I think the end product you produce is the only factor in pricing.  There is no reason for a client to have to pay for your expensive DSLR if you output photographs that could easily be made with a point and shoot.
So a good place to start is to look at other photographers and studios that output similar products (senior portraits) and have similar quality to your pictures.  Then check out their prices and maybe take an average.  This is a good place to start for sitting fees.
When selling prints remember that you aren't just selling the paper and ink -- your artistic talent, along with time dealing with printers, also went into producing that print.  Don't sell prints at cost.  This is also another place where it is a good idea to look at other photographers and studios for guidance.
Try mirroring prices of a nearby studio that does the same thing you do.  After a number of sittings, evaluate how well the prices you choose reflect your work.  Don't sell a valuable photograph for less than it is worth (called undercutting the industry and this is what makes 'pros' get so insecure and start to dislike you), but also recognize that you don't take the same photographs that a top-tier studio can.
Comment: Production may have no bearing on what the consumer will pay, but they do have a bearing on whether you can stay in business or not.  Don't set your prices for a new business based only on your established competition and disregard your costs.  Especially in this example, you may find yourself pricing against somebody with a much more streamlined workflow or tools that make his work more efficient - *that you don't have.  A new business can't compete on price*.  Set your price based on your costs and your time and if its not competitive with equivalent quality - you're in the wrong business.
Comment: I don't think the other answers are suggesting that one should _only_ price to cover costs, but that being aware of those costs is important in order to find a reasonable cost.
Comment: I don't agree with the notion that photography gear is not part of the cost model as it was already purchased before going into business. Any photography business has gear costs, it doesn't matter how those costs are funded or if the gear is used for both pleasure and business. A cost is a cost and gear is an ongoing cost. Charging should therefore always be cost + profit based, otherwise there is no point in going into business. If the end price results in a non-competitive offering, well then you don't have a business to begin with.
Comment: Agreed. The price of a product or service is what the market will bear. Production costs have no bearing on the price, only whether it is economically feasible to provide the product or service at that price.
Comment: @mattdum - Yup, costs must be considered.  This whole "price only against your competition thing" is *close* to what economists call "predatory pricing" and a business can't stay viable for long when they try to do this.  Photography IS A BUSINESS.
Comment: Keying off competition is a quick way to a losing proposition. I'd have a look at this answer (full disclosure: it's mine) for a good basic ballpark pricing strategy: http://photo.stackexchange.com/questions/7432/how-do-you-determine-how-much-to-ask-for-when-someone-wants-you-to-photograph-a-w/7442#7442
Comment: Commercial prices are generally set somewhere in the range between what the product costs to produce and what its worth to the consumer, so production costs do have a bearing. Where exactly in that range the price will be depends on the nature of competition in the market.
Answer: The key to setting your pricing is to figure out your costs, that way you can make an informed decision:
You need to not only consider the printing costs, but also all the other fixed costs:
As an example:
Costs per 3 years:

Camera - $500
Lenses - $1000
Accessories - $250
Software - $250

Total: $2000
Annual Costs:

image hosting: $100
website: $50

Total: $150
Per Project:

$10 - printing
$2 - gas

Total: $12
So your major purchases for 3 years would be $2000. To spread out the costs, we will split that up over 3 years, so $666.67 per year
If you want to break even and shoot 52 sessions per year (1 per week) then you need to charge
(amortized costs) + (per project costs) = minimum charge
(666.67 + 150.00)/52 + 12 = 27.71

to break even, covering the cost of your equipment. This is the bare minimum that you should charge, and as your skill improves you should charge more (you want to be paid for your time, right?)
This is obviously just an example and every person's costs are different, but hopefully this can be a good place to start to figure out what you will need to charge.
Summary
When starting out many people work at cost and some decide to work at a loss to build a portfolio, but you have to know what your true costs are in order to make that decision.
As far as what packages to offer, that is highly dependent on your local competition.  Find out what other local photographers offer and use their offerings as a starting point.  I wouldn't suggest copying their packages directly, but again, you want to make an informed decision.
Comment: @chills42: I think your example lacks a very important part of the pricing: Honoraries. All the things you listed are correct, but somebody else may have the same excat equipment and other costs, but the final product won't be the same. Your time and the preparation you've had that allows you to generate the output you do is what adds value to the product.
Comment: @Jahaziel Right, and that's why I've made it clear that all the calculations are just to get you to your *bare minimum* charge, basically, your break even point.  As you gain experience, hone your craft, and expect to actually make money on your work, then clearly your prices should go up accordingly.
Answer: One good guideline regarding pricing is the monkey principle:

Let's say your prospective client decides to ignore your photographic skill, and instead use someone totally incompetent to cut costs. They therefore decide to go to a local zoo and let a monkey shoot the pictures.
But there's a catch: the monkey has no camera. So they use local rental service and get some gear for the monkey to use. Monkey then snaps some pics and everyone goes happily home.
The moral of the story is that if you can produce better results that monkey + rental, you probably should not be cheaper than what it costs to rent the necessary equipment without your services.

Adapted from what I've read on John Harrington's blog some time ago.
Comment: How much is it to rent a monkey?  How much is the monkey insurance in your area?
Comment: @florin: In practical usage, you can approximate all monkey-related expenses to the cost of one reasonably tasty banana.
Comment: Guess the cost of rental of equipment + (minimum wage fee per hour * hours of shooting) is a more realistic formula. Assuming equipment is camera, lens, and computer to copy the jpeg files to a CD or DVD for a set of digital pictures with no editting and taken without any particular skill.
Answer: I agree with James that you should consider the fees that professionals charge.  However, there is a baseline cost of work for you below which you should not do the job.  Here is how you calculate it:
There are three components that go towards figuring out the value of your work. If you charge below the sum of these components you will be losing money.

Labour time
Fixed assets
Consumables

I'll address these individually, albeit briefly, below.  You will need to put some flesh on the bones of this calculation:
1. Labour time
This is difficult to estimate.  It is essentially the rate of pay needed to keep yourself in the manner you are accustomed too.  This is obviously a subjective measure - if you are giving up an afterschool job to take photos, then its probably the rate of pay from your other job.  If you don't have any need for income because your parents cover all your costs then you don't have to value your labour time at all! This is obviously a competitive advantage - other professional photographers not only have to sustain themselves, but often have a family to feed!  Its worth noting that for adults there is a socially acceptable minimum standard of living quantified by the minimum wage.
For the purpose of this calculation however, lets assume you are giving up a four hour shift of your after school job to complete this job for which you would otherwise be earning $10 per hour, or a total of $40..
2. Fixed assets
I am assuming here that you will not purchase any durable equipment for a photography job but will instead use equipment you already own (otherwise the calculation becomes a little more complicated, but is still tractable).  In this case, the contribution of your fixed assets (e.g. camera, lenses, car, accessories, etc.) is calculated as a proportion of their average lifespan consumed by use.  In some cases you can calculate this directly.  For example, if you are shooting with a 500D that you purchased for $750 with an average lifespan of 100,000 shutter actuations, and shoot 500 photos for a job the calculation looks like this:

Asset value x Amount of asset used / Amount of asset in average lifespan
= $750 x 500 / 100,000
= $3.75.

You need to reproduce this calculation for each of your fixed assets.  Rather than working this out directly, lets arbitrarily quintuple the figure for your camera body and get a value of $18.75 of the value of your fixed assets consumed by a job.
3. Consumables
This is the easiest component to calculate, as you can simply keep the receipts.  Lets assume that this job requires $10 worth of gasoline and $20 worth of photo printing.
This gives a cost of consumables of $30.
Value of your work
The value of your work is the sum of these components.  In this rather contrived example, that is:

Labour time + Fixed assets + Consumables
= $40 + $18.75 + $30
= $88.75

This is your break-even point, below which you should under no circumstances charge.  If you charge less than this amount you will be losing money.
Price of your work
Now, you need not charge your work out at its value.  Indeed, you would have no monetary incestive to run a business if you did so.  Instead, you need to make a profit by charging a rate greater than your costs.
Exactly what this profit will be depends on market forces.  You probably cannot charge as much as high-class professional studios, as they offer a quality of services you presumably do not at this stage.  However, you are likely to be the fortunate position (from the perspective of a business owner) that the cost of your labour time is likely to be significantly less than that of your competitors who are presumably raising families, etc.  Thus, you are in the fortunate position where you may be able to undercut your competitors prices and thus attract business while still making a profit (at least until your life becomes more expensive, either by getting expensive tastes or leaving home or starting a family yourself).
Comment: Not to be too picky with a good answer, but I would question a bit of your reasoning in the 'fixed assets' category. One of the interesting things to come out of micro economic analysis of business is that it can make perfect sense to operate at a loss (short term) so long as your variable costs are covered. I.e., you are already out the cost of the camera, lenses, etc. and that is money you won't get back either way. So you might as well (if necessarily) work for $40+$30=$70 in your example. That is your real break-even point. A minor point, because as you said, you do want to make a profit.
Comment: Not long term, no. But for an amateur just beginning to charge for their work, it might be an option to consider. Absent the economic lingo, it would probably go something like, "I have a camera anyway, so I might as well make a little money with it." This is not the kind of thinking that makes for a good business plan, of course, but it might suit some people who just want to dabble or who are learning while building a portfolio.
Comment: @Sean True, but this isn't really a viable long term strategy is it?
Answer: There are a few ways to slice this:
Charging just to make a little money on the side.
Or
Setting the appropriate costs for your services and time.
The former makes some sense: as a friend, you might want to give discount prices. After all you're doing people a favor, and maybe these friends have helped you out with pricing breaks. That's fine, so long as it's a tit-for-tat kind of deal, and it's a rare occasion. For example, I agreed to do the senior photos for my friend's daughter probono--he gave me one hell of a referral which landed me a really good (re:high paying) job.
However, this sounds like this is getting to be more serious, then you should consider the latter option.
For the latter, I recommend looking up the local branch of some professional photo association, skim the directory and find several photographers, especially those who's skill level you feel you could compete with, and see how much they charge for their services.
And price yourself near that level.
Food for thought:
By pricing yourself at the level of the competition you are essentially setting the proper value of the services you are providing. Just because you're an "amateur" does not mean the service you provide is any less valuable. Also, just because you're an "amateur" does not mean you should not attempt to act like a "professional." This means having at least:

one spare camera (rent if you have to)
multiple redundant backups including backing up images during the shoot
a legally binding contract that explains who retains what rights for the image
a model release form should you decide to use these images in your marketing (better to ask now, then later).
Comment: Remembering the value of work is an excellent point to make.
Comment: I want to upvote this more than once, because it emphasizes that the cost should be based on the level of skill you bring along, while at the same time you as the photographer, being paid a certain amount that will be out of the 'just amateurish league', also have to provide the professional infrastructure, too. While it works out 99% of the time, clients do not see the fact that they also pay for the security that there will be a photo even if the camera meant to take it in the first place breaks down ;-)
Answer: Whoever says you can do this with a point and click needs to stop talking. You need to offset your cost and pay yourself. When we in this industry get that one guy who thinks it's OK to shot with his point and shot and not charge anything it's like Walmart stepping in.
We buy our equipment because it will get the best results and the client is looking for the best results and they are paying for your talent. You got into this because you have a talent and a passion; don't undercut yourself just to make them happy. Pay yourself and help pay your overhead (remembering your overhead is not a studio with employees and such, it's you and your car).
In my area charging $150 for a senior/family session as long as the family is under like 6 people and then giving a CD with printing rights is about fair; or the other route people are taking in my area is like $50-ish for the sitting fee then offering $35 - $145 print packages.
Answer: For an update, the article " How Much Should Photographers Charge In 2016? " could give some help.
So:

Amateur: $25 – $75 per hour. (...) Different types of photography lend themselves to different pricing models. Event photography is generally based on an hourly or day rate. When it comes to commercial photography, some photographers, like me, charge on a per-image or per-project basis.
Depending on the photographer, the per-image pricing model is lower risk for the photography buyer, and rewards for the photographer for a job well done. Some photographers charge as little as $25 per photo, while top photographers receive thousands of dollars for a single photograph. (...) Rates also fluctuate depending on location. (...)
Student: $50-100 per hour / $25-100 per image. As with all types of photography, the student rate varies, depending on their photographic discipline, industry experience, and interaction with, or assisting, professionals. Some advanced students do – and should – command as much as professionals. (...)
Semi-Pro: $50–$150 per hour / $25-125 per image. These are photographers who have ambitions to join the ranks of the professional. They may have another job or income source to keep them afloat, but which they aim to leave behind. Sometimes their additional skills are compatible with their photography. Many compete with professional photographers for jobs, but are not quite ready to jump in with both feet.

For a professional:

Senior Portrait Photography $125-$300. This rate depends on many factors, such as the number of locations, changes of clothes, and reprint package that you chose. (...)

And now, ask yourself:

– How much do I wish to earn in a year?
– How much are my annual business expenses?
– What's my marketing budget?
– How many days will I likely work next year?

You also can calculate your costs at this NPPA calculator.
NPPA includes in the calculation the following:
Expenses

Office and/or Studio

Phone (cell and/or landline)

Photo/Video/Audio Equipment and Accessories

Equipment Service and Repairs

Computer(s) (hardware and software)

Broadband Internet

Web Hosting / Portal Service

Vehicle Expenses (Lease, Insurance, Maintenance)

Office Supplies and Furniture

Postage and Shipping

Professional Development

Advertising and Promotion

Subscriptions and Dues

Equipment and Business Insurance

Health Insurance / Deductibles / Copays

Legal and Accounting Services

Taxes and Licenses (Business and Self-Employment)

Office Assistance (Payroll, Answering Service, Intern, etc.)

Utilities

Travel and Entertainment

Income Factors

Desired Annual Salary

Non-assignment Income

Number of Days You Can Bill Per Year

Your Results

Total Annual Expenses

Weekly Cost of Doing Business

Overhead Cost for Each Assignment Day


Is real image formed by a single optical element always inverted and virtual image always erect?

Question: Question:
Is real image always inverted and virtual image always erect with respect to the object? Is there any single optical device (a mirror, or a lens, or anything else) which could produce a real and erect image or a virtual and inverted image? Till now, I haven't encountered such a device. Does it mean this is not possible? Is there any fundamental law which prevents the existence of an optical device which could produce a real and erect image or a virtual and inverted image?
I know that we could produce a real and erect image by using two convex lenses by placing them one after the other, where the inverted image formed by the first lens acts as an object for the second lens which again inverts it to give a resultant erect image with respect to the original object. Here we get an erect image due to two inversions. This question is about a single device which could produce a real and erect image without any intermediate inversion steps.
Edit:
It was asked in the comments what is meant by a "single optical device". By this term, I meant that the device is made of a single piece of material of same refractive index throughout. So a combination of lenses or mirrors which may produce real and erect images do not count.
Comment: As a reminder, please do not post answers or attempted answers in the comments. If you can answer the question, please post it as an answer. Thanks!
Comment: Your definition of a "single optical device" still allows e.g. a piece of glass with an air bubble (or other hollow shape) inside, which can in effect function as a pair of lenses.
Comment: @Ruslan: Thanks for pointing that out. I thought "_...single piece of material of same refractive index throughout_" would eliminate such a case. I was unable to frame a better definition of a "single optical device". However, I hope you understood the real intention of my question. If there's anything else to improve, kindly let me know.
Answer: A gradient index rod lens will form an erect or inverted image, depending on its length.  A SELFOC lens is usually designed to transfer an image from the flat surface on one end of a rod, to the flat surface at the other end of the rod.  A SELFOC lens is usually designed to produce an inverted image, but when made twice as long (that is, with pitch 1.0) it forms an erect image.  The ray paths for a single pixel on one surface go through the rod as shown below.  They come to an inverted focus in the middle of the rod, then back to an erect image at the other end of the rod.

This image is one frame from a video on the Stemmer Imaging website, though there are several companies who provide gradient index rod lenses.  This sort of device is sometimes called a "Contact Imaging Sensor", and would be one element of a "line scan bar".
Edit #1 Some other approaches might meet the uniform refractive index, single-element condition:

Retroreflection: A ball lens with a refractive index of 2.0 and a highly reflective coating on its back half will return light to its source.  That means that an erect real image is formed from an erect source image.
Fly's Eye lens:  A slab of glass or plastic with small lenses on both sides can form an erect image.  Each lens on one face of the device forms a small field-of-view erect real image via the corresponding lens on the opposite side of the slab.  The lenses and the slab thickness are designed to ensure that the imaging is precisely 1:1, and the images all add up.  This is the principle of the contact image sensors (line scan bars), and is a variation on the principle illustrated by @BarsMonster: just build an array of the rod lenses he described, and fuse them together to eliminate boundaries between the rods, leaving only lens bumps on the surfaces.  Of course this element can be cast in plastic.

I'm pretty sure two optical surfaces are required, when the refractive index is positive, because we can show that an single optical surface (reflective or positive-refractive) can only form an inverted real image.  HOWEVER, negative index materials, in principle, can do it with only a flat, parallel-faced slab. See "Negative refraction makes a perfect lens" by Pendry.
Comment: _"See Science Direct article"_ — which one?
Comment: Thank you for your answer. If I understood properly, "gradient index" means the device is made of a material of non-uniform refractive index. I understood that we could produce a real and erect image using a SELFOC lens through an inversion process as depicted in the ray diagram. Is it possible to produce a real and erect image without any intermediate inversions? Further, is there any optical device of uniform refractive index which could satisfy the conditions mentioned in the question?
Comment: I have added edits that I think provide a complete answer - and a solution to the problem.
Comment: I changed the link to an original paper by Pendry, and the image to an image from Pendry's paper.
Comment: @S.McGrew: Thanks for making the edits :) So, the answer to the question "_Is real image always inverted and virtual image always erect with respect to the object?_" is no. And you provide examples of SELFOC lens, negative index materials etc., which produce real and erect image (well through intermediate inversion steps). However, the main intention of my first comment remains the same - Is it possible to produce real, erect images or virtual, inverted images by an optical element of uniform index without any intermediate inversions?
Comment: To be honest, I really learnt many new interesting things from your answer. It's really informative and it belongs to a level much higher than what I expected when I placed the bounty. Thank you for all your efforts.
Answer: I can only think of multiple optical devices combined in a single entity in a way to not violate your restrictions of being single device. Ether double lenses merged into one, or prism/mirror merged with a lens, or first surface curved mirrors with multiple reflections, while all this still being made from 1 piece of glass.
Comment: Thank you for your answer. I'm glad you understood my definition of a "single optical device". I think the ray diagram in your answer produces real and erect image through an intermediate inversion process (at the middle of the device where blue is below green which is below red). Even though the diagram clearly answers the question, I'm curious to know is it possible to produce a real and erect image as a direct process without any intermediate inversions?
Answer: Correct me if I am wrong, by "single optical device" you meant the device should either converge or diverge or do nothing to the parallel rays.
If we want to create a real image of a point light source, all the divergent light rays from the source must converge again to a point after passing through the stated device. In order to get an erect image, rays diverging from the point source, if present above central line, must also converge the above the central line. Consider a ray coming from the source and passing through the center. This ray must follow a V-Shaped path to get an image above the center line, which is impossible (because it won't be convergent anymore). I tried to depict my argument by a figure, it's not a very good drawing though.
Comment: Thank you for your answer. Can you explain why the real erect image in your diagram is impossible?
Comment: @GuruVishnu I explained the same with my text. By definition, single optical device can't converge and diverge both for a same light source but different rays.
Comment: Thanks. I understood the general optical elements we find in textbooks like convex, concave lenses could not produce real, erect or virtual, inverted images. Your answer explains that really well. However, as stated in the question, I believe if we aren't aware of such devices that doesn't imply real, erect or otherwise couldn't be produced. Are you saying real, erect image couldn't be formed by a single optical element without any intermediate inversion processes? If yes, it would be helpful if you could specify why it's not possible to have real, erect images?
Comment: All I am saying a real erect image is possible only when multiple divergent rays from a same light source behave differently after passing through a single optical device: at least one should converge and all other should diverge which is highly illogical. The simple device would follow the same logic in terms of bending the light.
Comment: I'll give it some more thought. However, I've upvoted your answer. Thanks.
Answer: From the mirror formula ;
$$\frac{1}{f} = \frac{1}{v} + \frac{1}{u}$$
magnification formula ;
$$ m =\frac{h_{image}}{h_{object}} = \frac{-v}{u}$$
and commonly used sign convention , it's easy to see that how it all works. An illustration as a hint is provided below for a special case.
Illustration:For a concave mirror when $u<f$:
As said , with cartesian sign conventions, we have
$f<0 , u<0$ and $ u<f$, we get ;
$1) v<0$ ( which means rays are not divergent and hence real )
$2) \frac{h_image}{h_object} < 0$ ( which means that image is inverted ).
It would be a good exercise if you verify all other cases yourself. Good Luck !


Ensuring strict concavity on log utility functions

Question: Given a vector $\vec{x}={x_1,x_2,\ldots,x_n}$ ($x_i \geq 0$), why is it that in a function $U(\vec{x})=w \log \left ( \sum_{i=1}^n x_i \right ) + \varepsilon \sum_{i=1}^n \log (x_i)$ the $\varepsilon$ term is is said to ensure strictly concavity for the function $U(\vec{x})$? Why is $V(\vec{x})=w \log \left ( \sum_{i=1}^n x_i \right )$ (i.e. without the $\varepsilon$ term) not strictly concave? Is there any relation of this with the log-sum inequality, i.e. for non-negative numbers $a_1$, $a_2$, \ldots , $a_n$ and $b_1$, $b_2$, \ldots , $b_n$, we have $\sum_{i=1}^{n} a_i \log \frac{a_i}{b_i} \geq \left ( \sum_{i=1}^n  a_i \right ) \log \frac{\sum_{i=1}^n  a_i}{\sum_{i=1}^n  b_i}$ with equality iff $a_i/b_i$ = constant?
Answer: The sum $\sum$ is not a strictly concave function. So you might have $\vec{x}$ and $\vec{x}'\neq \vec{x}$ such that $v=\sum_i x_i=\sum x_i'$. Then for every $\lambda\in (0,1)$, $v=\sum_i \lambda x_i+(1-\lambda)x_i'$. Hence $w\log(\sum_i x_i)=w\log(\sum_i x_i')=w\log(\sum_i \lambda x_i+(1-\lambda)x_i')$. So $w\log(\sum_i\cdot)$ is not strictly concave.
But the sum of a concave function and a strictly concave function is strictly concave, so adding the $\epsilon$-term ensures strict concavity (the logarithm is clearly strictly concave).
Comment: Thanks a lot, Michael! In fact I suspected the convex function property $f(\theta x_1 + (1-\theta) x_2) < \theta f(x_1) + (1-\theta) f(x_2)$ played some role here, but I simply forgot this other property you mentioned, i.e. the sum of a concave function and a strictly concave function is strictly concave, so you were of great help!


Are Frictional Forces Always Shear?

Question: Is frictional resistance always shear? Two examples I am thinking of are the cases of friction between solid bodies and "friction" in viscous resistance?
Answer: Viscous resistance can be normal to or along the surface. Resistance that is normal to the surface is usually called pressure, and the ones that are parallel to the surface is usually called shear.
Viscous stress tensor : https://en.wikipedia.org/wiki/Viscous_stress_tensor
The diagonal elements represents the normal pressure and the off-diagonal elements are the shear forces.
Comment: Wikipedia's stress tensor explanation does not make much sense to me, so I will look into other explanations.
Answer: Friction between solids is an adhesive process not a shear process. For a discussion of this see How is frictional force dependent on normal reaction?
However in most cases energy is also dissipated due to elastic deformation of the materials involved. The frictional force at the interface between the two materials causes elastic deformation of the bulk due to the shear stress. Although this is elastic in the sense that no permanent deformation is produced, energy is dissipated as the material flexes. So in this sense shear is involved even in solid friction, though it not a shear flow as it would be in a liquid.
Answer: In fluid flow past an object, the force per unit area at each location on the surface can be resolved into a normal component and a shear component.  The integral of the normal components over the surface (resolved in the flow direction) is usually designated as the "form drag" and the integral of the shear components over the surface (resolved in the flow direction) is usually designated as "frictional drag."  The shear components are strictly viscous, but the normal components are comprised of a combination of viscous stresses and pressure.

Are Frictional Forces Always Shear?


thermostat c wire question

Question: I am looking to install a new thermostat that will require a C wire. I have a single stage A/C unit and my current thermostat has Rc, G, and Y wires. There is also an unused blue wire which I traced to the A/C unit electrical panel - it is not connected to anything. My problem is - the guys that installed my A/C were kind of "half ass" and there is no easy way for me to just connect the unused blue wire in the A/C electrical panel. The unused blue wire is wrapped around the brown wire.
Comment: Unused low voltage wires in HVAC and telco, are often wrapped back around the cable.  It's a very common practice, which allows the wire to be used as needed in the future. Instead of criticizing the installer for doing this, you should thank them. Unwrap the wire, and use it as your `C` wire.
Answer: You should be able to see onto the board where the rest of the wires connect and find the "C" terminal. It likely already has something connected going to one of the many wire nuts (and yeah, that is pretty sloppy).
You can test for sure using a multimeter. Set it to measure AC voltage, and then between the Rc (or Rh) and C wire you will see around 24VAC.
Once you've traced C and verified it, connect it up to your blue wire. Do yourself (and anyone who works on this in the future) a huge favour and label each wire at the thermostat before you put it back in the wall.
Comment: Thanks gregmac - my one question is there is no standard board like you'd see in other HVAC units. Also, nothing is labeled R or Rc or anything like that. I can see where the power comes in from my shutoff switch, but it already has other wires connected to it so I'm not sure if I can just add the common wire to that with another wire nut.

thermostat c wire question


Simulating a load dump circuit

Question: I am trying to build automotive load dump circuitry to bench test my inverter design. I would like to know if anyone has any experience building something like this. I need to create a 172V spike that stays for 400ms.
Comment: Out of curiosity, why 172V for 400ms? I have seen in a couple of places that 60V for 5ms is a typical design point for automotive load dumps.
Comment: This is the requirement for the automotive application we are working on .
Comment: I was planning to charge up a big inductor and then open the switch to dump all that energy into my board. I was checking to see if someone already has built something like this up.
Comment: How much current?  I can rub a balloon on my wool sweater and get kV's that last for seconds.
Answer: Here OP is talking about ISO 7637 PULSE 5a, which is simulated version of load dump situation in automotive.
Specification of pulse 5a 12V(two wheeler) and 24V(4 wheeler) are shown below:
As it shows maximum of 174V can be produced for 400 ms in case a load dump situation occurs in the vehicle. And if load dump occurs all the electronics circuits will be fried if not protected.
Now,

What is Load Dump?

The worst instances of surge voltage are generated when the battery is disconnected when the engine is in operation, and the alternator is supplying current to the power line of the vehicle.
To test the circuits whether they comply with ISO 7637 PULSE 5a, it needs to be tested with Pulse 5a generator, like the one shown here.

Pulse 5a Protection

There are couple of good documents on internet about protection from Pulse 5a, and a suggestion 5KP series diodes are suggested to use, and some times two diodes in parallel are also used for protection.
Comment: @DaveTweed: I have mentioned about pulse generator using the link of noiseken. http://www.noiseken.com/modules/products/index.php?content_id=202
Comment: This is not an answer. You've described everything that the OP already knows, but you've failed to answer the question about how to generate/simulate the required pulse.
Comment: I read your answer Dave, which you have mentioned with the duplicate link. Thank you for improving my understanding about load dump simulation.
Comment: Dave - Could you please point me to duplicate post you were talking about?
Comment: Dave- I built a circuit similar to what you have posted in the duplicate post- inductor charging and discharging circuit. If I don't want to test it with my DUT yet, do I  need to attach a dummy load to it to test it?

Simulating a load dump circuit


Is rendering Markdown to HTML considered an "adaptation" under CC BY-SA 3.0?

Question: Title pretty much sums it up. Are the rights given to adaptations granted if someone renders Markdown?
Comment: Another post on the CC-BY-ND license with some relevance to this question: https://law.stackexchange.com/questions/51603/is-usage-of-a-still-frame-from-a-video-considered-a-derivative-work-adaptation
Answer: Usually not, usually
Translating literary works is generally regarded as an adaptation, but I don't think translation programs—and HTML and Markdown, two markup languages with similar principles—are adaptations. According to the description on Creative Commons,

Merely changing the format never creates a derivative.

So changing WAV to MP3 is not considered an adaptation, nor is changing DOC to PDF. As for HTML and Markdown, it seems a bit vague, but it can be said that although their encoding methods are different, the results presented are very similar.
According to https://creativecommons.org/faq/#when-is-my-use-considered-an-adaptation,

a modification rises to the level of an adaptation under copyright law
when the modified work is based on the prior work but manifests
sufficient new creativity to be copyrightable

Adaptation produces a derivative. A derivative contains both the will of the original author and the adapter. Creation involves choice, the painter chooses the colors to use, and the translator chooses the words to translate. There are inherently fewer options to create a program. Rendering markdown to html can be done directly through other programs, and it is difficult to see the shadow of the adapter. Editorial originality is very import.
Yet one more thing is important: legal definitions. This is what it says in the https://creativecommons.org/faq/#what-is-an-adaptation FQA page

What constitutes an adaptation depends on applicable law

So, the laws of where you live still matter. We all know that there is a large gray area in copyright law, which often makes everything depend on the actual situation.
This is just a little bit of my personal thoughts for your reference :)
Answer: A clear answer is yes, MD was the original source, and it is modified to an entirely differentiated version of HTML. Under the definitions of the Creative Commons Attribution-ShareAlike 3.0 (CC BY-SA 3.0) adaptation is generally covered. Citing the legal code of the paper, adaptation is defined by Section 1 of Article a as:

"Adaptation" means a work based upon the Work, or upon the Work and other pre-existing works, such as a translation, adaptation, derivative work, arrangement of music or other alterations of a literary or artistic work, or phonogram or performance and includes cinematographic adaptations or any other form in which the Work may be recast, transformed, or adapted including in any form recognizably derived from the original, except that a work that constitutes a Collection will not be considered an Adaptation for the purpose of this License. For the avoidance of doubt, where the Work is a musical work, performance or phonogram, the synchronization of the Work in timed-relation with a moving image ("synching") will be considered an Adaptation for the purpose of this License.

From this, you have to note this instruction clearly:

or adapted including in any form recognizably derived from the original,

The output of the HTML seems that content is clearly derived from the original work does not mean it is not an adaptation. It is counted as an adaptation.
However, there are no exclusive rights granted, the adaptation is of similar content so using the same license and citing the original author is compulsory.


Can an inspector require a specific grounding technique?

Question: I had been taking classes to become an electrician at one of the bigger community colleges in my area (specifically LBCC) and my brother had been doing some renovation on his own home and asked me to help out so I wired up the boxes and switches and receptacles and while we grounded the switches and receptacles we forgot to ground the metal boxes them selves and the inspection failed but my brother tells me that the inspector said we're not allowed to pigtail the grounds between the boxes and devices that we have to use a long ground wire loop it around the boxes ground screw then run it up to the ground screw on the device ... can he do that? this runs counter to what I was taught which is to pigtail the wires to the devices and ground screws
Comment: If LBCC is in Oregon, I am sorry for you. Our inspectors really mess with home owners. There are some fine points on grounding I have seen them cite, yes the boxes have to be grounded and there are 3 ways they will pass locally. First the long ground looped to the screw as your brother said. Second crimped iriversable pigtail. Third a pigtail with a listed green grounding wire nut that the ground lug comes out of the top of the cap. There may be other ways but these are the methods I have seen that will pass in the Lynn, Benton and lane counties (LBCC)
Comment: I don't think there's anything that says the ground has to be continuous in NEC, but it could be a local ammendment.
Comment: What happens where you have more than one device in a box?
Comment: Are you sure there isn't a misunderstanding of the inspector's words through your brother? I could definitely see an inspector telling your brother you cannot just add another pigtail between the box and the ground screw on the device to fix the problem (because you cannot have multiple wires under a single ground screw/terminal--which just adding a pigtail would do). Perhaps that is what the inspector meant? However, if you rewire to where you have a single pigtail running to each grounding screw, then there shouldn't be a problem unless there are ridiculous local amendments in force.
Comment: When you screwed down the switches and receptacles to the metal boxes, are they fully seated hard flush on the metal boxes (not suspended out on drywall ears)?
Comment: they were seated flush at the time but I can see how that might not matter to the inspector as this is rough in phase only wall frame is up not the drywall or what ever he's going to put up over the frame so they might get loosened later for that
Comment: I just noticed testers comment on grounds not having to be continuous. Here the use the justification that a ground must have an irreversible listed splice if not long looped, the listed green wire nuts with the hole in the top are allowed by most but not all. I think those are better than irreversible crimps because if repairs or modifications are needed the ground has to be cut. I usually add a small service loop next to the boxes for this reason.
Answer: If you are taking training this can be found in the NEC section 90.4 "Enforcement" the second sentence states he is the legal jurisdiction having authority for the enforcement of the code and he has the responsibility for making interpretations of the rules, ...
So in answer to your question yes.
The only thing you could do is to appeal it to his employer (the city council or whomever) or try and reason with him. Personally I wouldn't try and tick him off.
Answer: Like the 'Retired Master Electrician' said, yes they can as per the NEC....but too the fact is that the NEC are standards, and are accepted by the individual city as guidelines, but the code that you live by ULTIMATELY depends on the LOCAL regulations...and specifically where the NEC contradicts local regulation, local regulations are the only thing that anyone give a hoopla about.  Generally the inspector will be under what is known as a "Project Engineer" or "Project Manager" for the jurisdiction under that governs the applicable inspection of electrical in the area.  The other thing though to be aware of is that even if the inspector is a moron.....make sure you have your ducks in a row before you call him one....because they can have quite a bit of power and authority (it depends on the situation of course, but I am telling you this from experience as an Electrical Inspector for the State of Alaska for several years on quite a few multi-million dollar projects.  My boss would back me even if I was wrong if he could have excused it politically.  It is just how things work ....its a game in many ways that you have to play to be successful (imho)...
Comment: If LBCC is in Oregon a supervising electrician is the same as a master + engineer in other states. A supervising electrician can design and install any electrical project in the state of Oregon.
Answer: Electric inspectors are about the only trade that has that authority.
Inspector Jeff
ICC/FL/SC licensed combination building inspector and building designer
Comment: I think that there's really no question that the inspector in question's an electrical inspector -- also, there's no need at all to sign your posts.
Answer: A wirenut/clamp is a continuous connection. Crimpclamp a ground connection in there and you're good to go. I do agree with your inspector - pigtails are worthless except in commercial work where you may run into alot of BX/MC cabling.
One thing you should learn in contracting - always know where to find it in the book. That trumps all inspector's opinions. You can politely point out discrepencies with your inspector, and earn respect.
Comment: If the AHJ says it is wrong and won't sign off it may be a local issue or a questionable call. They have the authority to have power disconnected from the service If there is a safety concern. I had a contractor friend bring me in to get power restored after a PISSING contest that he won but the customer was shut off for almost 1 week because the AHJ is just that they have the authority even over a supervising electrician in my state or in other states an electrical engineer + a master electrician.


Global hotkey not working in Chrome or Intellij

Question: I'm trying to create a global hotkey which can be used with any application open. Currently the shortcut is ^ Control⌘ Command⌥ Option⇧ ShiftP, though I've tried a few other keys as well. With most of the applications I use, the shortcut works, but when Chrome or Intellij have focus, nothing happens.
Answer: Apps can enable/disable shortcuts as their developers see fit.  In fact, they can completely override system defaults and choose to ignore any custom shortcuts you may have defined.
Chrome is notorious for this.
In Apple's Human Interface Guidelines, it specifically tells devs to "respect standard shortcuts."

Respect standard keyboard shortcuts and create app-specific shortcuts for frequently used commands. Keyboard shortcuts let people activate menu items and actions by pressing specific key combination.

Apple advises devs not to remap the standard shortcuts but we know that they do it with their custom method of closing the browser.  Press and hold ⌘ CommandW to close the selected Tab.

In general, don't override standard keyboard shortcuts. Users may become confused if the shortcuts they know work differently in your app. Only in very rare cases does it make sense to redefine a common shortcut. For example, if people spend a significant amount of time in your app, it might make sense to redefine a standard shortcut that isn't applicable to your app. Another option might be to let the user choose their own keyboard shortcuts.

So, while Apple obviously frowns upon redefining shortcuts - you still can.
So, why doesn't your key combo work? Chrome (and I suspect IntelliJ as well) have configured the application to ignore or rewrite certain system user defined key combinations.
Comment: What are the ways to get around it? I was able to accomplish what I wanted by using Alfred, but I'm wondering if there's a way without resorting to 3rd party software. Also, any idea how apps like Alfred are able to listen to shortcuts no matter which app has focus?
Comment: Google devs are doing it in code so you can't really (unless you "fix" the code in Chromium and maintain that fork).  Alfred can listen for shortcuts by listening to System Events.  Alfred's capabilities stop short when the App doesn't register the event but just executes it instead.  So, it's more accurate to say "...no matter which app that registers the event has focus"


How to clip very large shapefile in QGIS using ogr2ogr?

Question: I need to clip a large shapefile (600,000 KB) to another smaller shapefile (10 KB).  The vector -> geoprocessing -> clip command is taking very long.  Answers to similar questions say to use "ogr2ogr" but I am not sure where to start in installing ogr2ogr.  I have no Python experience either, not sure if that makes a difference.
Comment: OK, I'll try downloading and using 2.18.  (As an aside - does anyone know if 2.18 should speed up other processes in general, like using the field calculator to create a new field for the attribute table for millions of rows of data?)
Answer: On windows environnement, if you installed Qgis with OSGeoW setup you have access to a shell which can run directly gdal/ogr.
to run a clic processing use this command
ogr2ogr -clipsrc clip_polygon.shp output.shp input.shp
replace output and input with your files name and their path.
If you need more details about OSGEOW have a look to this page
Answer: Upgrade to a recent 2.18 release. From the change log:
"
Before the algorithm was written to optimise clipping a few
features against thousands of mask features. The revised algorithm
is optimised for clipping thousands of input features against
a few mask features.
Given that this second operation is much more likely, it makes
sense to optimise for this use case.
I've also applied some other optimisations like taking advantage
of spatial indexes on the providers, using prepared geometries
and also only applying an intersection operation if the geometry
isn't wholly contained by the mask geometry.
Benchmarks:
clipping roads layer with 1 million lines against 2 polygons
before: 5 mins 30 seconds
after: 10 seconds
clipping address layer with 5 million points against 2 polygons
before: 50 minutes
after: 30 seconds"
Comment: well thank you very much for doing that, champion, good'on'ya!
Comment: Thanks, that worked.  QGIS 2.18 really makes a huge difference with clipping.  It is buggy, however, with creating new fields in layer|properties (see https://gis.stackexchange.com/questions/258567/how-do-you-speed-up-creating-new-field-in-attribute-table-for-huge-amount-of-dat)


Tool in WoW to find a compatible guild based on a profile

Question: Is there currently a tool available on the web where I can put in my character information, times I like to raid, what kind of content I am looking to raid and/or whether I PvP, and guild leaders across the board can contact me via? I am willing to pay the cost of changing servers for the right guild. Blindly transferring to another server is too costly so I was wondering if there is an effective tool out there for finding a good guild. I see WoW Progress is out there, but I'm not sure how often that is used to contact individual players. Also, it doesn't allow me to enter my character if I'm already in a guild, which is a show stopper. I am not entirely ready to leave the guild I'm in now unless something better comes up.
Answer: The Guild Finder tool does exist in-game, but it is not widely used, since many people believe you have to be guild-less to use it.  You can bring it up using the <code>/gf</code> command.  There are some external resources, though.  Blizzard hosts a Guild Recruitment Forum on their own site that is pretty widely used and is probably your best bet to find a match just by looking through the threads until you find something good.  There are a couple other forums for guild recruitment, such as the Elitist Jerks forums, MMO-Champion, or TankSpot.
There are also some standalone websites, but I'm not sure about their quality.

Guildster
Wowmatcher
Wowstead

P.S. - If you're looking for a PvP guild, I'd recommend checking on Arena Junkies.
Comment: According to http://us.battle.net/wow/en/forum/topic/2483689459#10 and others I've read, you can type /gf or /guildfinder to bring it up at any time, you can be guilded or unguilded. So your statement above is incorrect.
Comment: Oh, hey look at that. I had never heard of that option.  As the guy said in the post below that blue post, nobody ever mentioned that.  Updated the answer.
Comment: Also if you don't get any bites from the guild recuitment forum on us.blizzard.net, try the individual realm forums that you belong to and put a LF Guild post there. Sometimes guilds don't bother to read the other forums on us.blizzard.net. Personally I only read class forums on there.
Comment: True, realm forums are also good. Although they seem to have really died out recently.  That might just be my realm though.


What is the origin of oil?

Question: Most people may believe that oil comes from dead plants and animals, but there are alternative theories that are known as Abiogenic Petroleum Origin. If oil in generated in this manner it could mean we could find oil on other planets or moons as well.
Answer: As far as we can tell, almost all crude oil (petroleum) is biogenic, and specifically comes from marine organisms. That's the only theory that is supported by the geological record, by the thermodynamics, and by what we know of the biology and the chemistry.
That's not to exclude the possibility of abiogenic petroleum: indeed, we know that abiogenic liquid hydrocarbons are possible, because we can synthesise them ourselves. So finding hydrocarbons that cannot be biogenic does not show that most fossil fuels are abiogenic: it merely shows that some abiogenic hydrocarbons exist.
However, the quack theory, popular in Soviet Russia and with other fringe pseudo-scientists, is that almost all oil discovered in the ground comes from abiogenic sources. Geoff Glasby looked at how the pseudo-science came about, in his article Abiogenic Origin of Hydrocarbons: An Historical Overview (Resource Geology, vol. 56, no. 1, 85–98, 2006) DOI:10.1111/j.1751-3928.2006.tb00271.x
Answer: Dead macro-organisms, plants and animals, are not necessary to form oil. For example consider oil from the Pre-Cambrian siltstones of Oman, which formed long before the evolution of land animals or plants. On the other hand, EnergyNumbers is correct, that the hypothesis of abiogenic origin of oil, proposed by creationists, etc., is completely defunct. There is plenty of abiogenic hydrogen in the Earth, such as released through the process of serpentinization, but it takes more than hydrogen to make oil. In fact there are three requirements: kerogen, temperature and time. The kerogen comes in many forms, being derived mainly from marine and lacustrine microbiota, and also from higher land plants. A  small fraction also comes from weathering of polycyclic aromatic hydrocarbons. These provide the complex polymers, in some ways similar to the tannin in your tea, from which the more complex oil molecules are formed. Oil is a complex cocktail of compounds, of which I would cite in particular the C27-C29 steranes as being indicative of the oil's age. It takes hundreds of millions of years under warm pressurized conditions for the 'C29' type of oil to evolve. I cannot envisage any conditions in which these compounds could evolve from simple methane-type precursors. That's not to say it is impossible (maybe my limited imagination?), but it's very improbable.
As for oil on other planets, without life, first define what you mean by 'oil'. Simple organics are widespread, both in the Solar System and beyond. More complex organics probably require life to evolve, especially in the cold conditions of moons in the outer Solar System. But who knows what exists in the hidden ocean beneath the icy surface of Europa? I would be surprised to find 'Earth-like' oils in this ocean, but the evolution of simpler oils in this environment would seem eminently plausible.
Comment: Isn't it true that creationists believe the Earth is 6,000 years old, while abiogenic oil proponents are referring to Pre-Cambrian time frame of 500,000,000 to 4,600,000,000 years ago? Then how honest of you is to refer to whoever proposed the abiogenic theory as "creationists"?
Comment: I have read some of the creationist literature on supposed 'recent' formation of oil, and I make no apologies for labeling their argument as facile junk science. Of course, there are other non-creationists arguing for abiological oil. As for Thomas Gold, I corresponded with him in the late 70s and early 80s. His main contribution concerns the deep abiological generation of hydrogen and methane. That much is strong. The supplementary argument of methane being a precursor of oil is weak.
Answer: So far the science has reached the following conclusion (from this report):
"Extensive scientific research and practice have proven that a relatively large percentage of hydrocarbons, especially oil, are generated organically. However, this does not rule out the possibility that another large proportion of hydrocarbons, gas in particular, may be of abiogenic origin."
However, oil exploration on planets and moons is a way far reaching proposition.
Comment: I wouldn't say that "science has reached" a "conclusion" based off of one paper. That paper (that I can't even access the full text of) could be completely refuted by a bunch of other papers.
Answer: Actual environmental scientist here. Crude oil and other similar "fossil fuels" are the result of organic materials held at intense pressures for millions of years. That is the only theory accepted by modern scientists outside of the Ukraine. There is no other theory, because no other hypothesis has been supported with the kind of evidence necessary to even consider mentioning it in conversation. Anything that says otherwise is pseudo-science.
Oil = organic materials
Comment: Just a semantic point regarding "Oil = organic materials". Methane and other simple aliphatic molecules are organic, but not oil! The oil under discussion here is a highly variable and complex mix of molecules.

What is the origin of oil?


Finish reading or finish of read. Why we use gerund forms as infinitives verbs?

Question: I see that some words in English are expressed in gerund, with the meaning corresponding to the infinitive, and used as infinitive verbs. Could someone please explain to me, why does this happen?  I'm a spanish speaker :)
Comment: Could you give an example of a gerund being used as an infinitive? It is unclear what you mean by that.
Comment: No entiendo su pregunta. ¿Qué significa "gerund meaning"? o ¿"used as infinitive verbs"? Unos ejemplos de lo que usted no entiende nos ayudarían a responsarle.
Comment: (Y N.B. que "finish of read" no es gramatical, por eso no se considerará como ejemplo . . .)
Comment: I've reopened this only because I believe that it was closed when the wording was unclear, and that the edits make the question clear. If anyone feels this is in error, especially Camilo Espinosa, please just speak up.
Answer: In English, the gerund phrase can be used either as a substantive or as a modifier. But in Spanish, gerund phrases can only ever be modifiers, specifically adverb phrases. So if you want to treat a verb phrase as a substantive in Spanish, you can only use the infinitive form there, never the gerund.
Since they're fine as substantives, infinitive phrases work as subjects or objects in both languages:

To drink is to live.
Beber es vivir.
He went there in order to see it.
Fue allí para verlo.

Similarly, you can use a gerund phrase as a modifier in both languages:

Starting his night as always, Daniel left singing out loud.
Empezando su noche como siempre, Daniel salió cantando en voz alta.
I arrived late, having forgotten her address.
Llegué tarde, habiendo olvidado su dirección.

But when English uses a gerund phrase as a substantive, the Spanish version must always use only an infinitive phrase instead:

Seeing her at night is harder.
Verla por noche es más difícil.

This is why Spanish speakers first learning English have questions like the original poster's.


Do I have to Cite an Image I have edited?

Question: I have received an Image from a source I am not sure about, I have edited it to suit my own project, now do I have to cite the main source?
Comment: Question aside, why would you use a source you are not sure about? Maybe this is licensed in a way that you are not even **allowed** to edit it, much less publish the edited version.
Answer: Of course, should you cite the original sources (just use the golden rule: think how you would like to be treated if you were the author of the original source). You may say something like
<code> adapted from < Figure X of original source >
</code>
However, as indicated in the comments, you should make sure that you have the right to do so. Note that sometimes it is possible to "read" the data values from an image and create your own image from those (but you still need to quote the source of the data).
Answer: I tend to use (author as derived from_________)
Your best bet is to use open sources. For example, when I manipulate maps I use openstreetmaps.com. Their policy explicitly allows for editing.
Otherwise, if the license is unknown, i.e. the author does not specify in any way, then you should contact the author and receive formal permission (this might need to be done with a form), if it is for formal publication.
Answer: I wouldn't use the source if you are not sure about it, and just use a new image.
Comment: It seems it's just your personal opinion. In order to develop an effective answer to a question you need to elaborate your reasons more concisely and give some example why you have this opinion regarding this matter.


Laser Colimator vs Cheshire eyepiece

Question: Both the laser collimator and cheshire eyepiece are tools used in astronomical telescope collimation. What are the main advantages/disadvantages of each? Which one might be best suited to start with for telescope newbies?
Comment: I think it's better to turn to the `edit` button than the `insta-close` button when the only problem is the way the question is phrased. This is certainly a good question and was pretty clear from the beginning. Saying "unclear what you're asking" is not the most helpful response here. I'm going to point to the [this excellent, accepted answer](https://astronomy.stackexchange.com/a/22310/7982) as supporting evidence that the question was already both *clear* and *excellent* and there was absolutely no need of closing it. SE is not Space Invaders and the goal here is not to shoot things down.
Comment: What is your source?  What are you trying to achieve?
Comment: @CarlWitthoft what do you mean by "my source" I heard collimation lasers need also to be collimated  which is tricky and are more expensive and are not always reliable. I just want advice from somebody with experience using both tools to tell its advantages and disadvantages I don't get the downvote
Comment: By "source" I mean the object which is creating your photons
Answer: Why not both? (if you can afford them)
Both will do the job, but each has its strengths.
Cheshire eyepiece (or, more properly, Cheshire/sight tube combo, which is the popular combination nowadays):
It's easier to use when the scope is grossly out of alignment. Like, when you put it together for the first time, or after it dropped on the ground and rolled downhill for a minute. But can you do that with a laser? Yes.
It's easier to align the secondary mirror, and it tends to produce dead-on results for this purpose. But can you do that with a laser? Yes.
It is not immune from precision issues. Most parts of the Cheshire are usually well aligned (because they are machined on a lathe), but the crosshairs on the sight tube may or may not be perfectly centered. But can lasers also suffer from alignment problems? Yes.
Recommended Cheshire / sight tubes: the ones made by Catseye.
http://www.catseyecollimation.com/
They make much more than just Cheshire eyepieces, and all their tools are very high quality.
Laser collimator:
It's faster and arguably easier to use for normal daily collimation before you begin your normal observing sessions. But could you use a Cheshire instead? Yes.
A laser is only as good as its own alignment precision. A misaligned laser will not collimate your scope properly. But do Cheshire sight tube combos suffer from precision issues with their crosshairs? Yes.
Recommended laser collimators: the laser collimator and the tuBlug combo made by Howie Glatter. Unfortunately Howie has passed away recently, so either wait until someone picks up where he left off, or find a used laser/tuBlug combo somewhere on eBay or classified ads.
http://www.collimator.com/
Howie's lasers are essentially guaranteed to have zero collimation errors from factory. From anecdotes told by users, these devices tend to keep their perfect collimation even after being dropped to the ground repeatedly.
The tuBlug is not mandatory, but it makes primary mirror alignment much easier.

Keep in mind that you also need a precision center mark on the primary, for these methods to work well. Hopefully it's been placed there precisely from factory; otherwise there are ways to re-center it.

How to verify if the laser is centered:
Place it in the focuser. Do not tighten the screws too much, allow the laser to rotate in the focuser a little bit.
Turn the laser on. Watch where the spot hits the primary. Now rotate the laser in the focuser. If the spot describes a circle as you rotate the laser, then the laser is misaligned.
Different method: Make a V-shaped trough from 2 pieces of wood or aluminum. Placed the through horizontally on a sturdy table. Put the laser on the trough. Turn it on, projecting the spot on a distant flat object, like a wall or fence across the street.
Now rotate the laser in the trough and watch the spot. Does it stay put? Then the laser is fine. Does it move in a circle? Then the laser is misaligned - find the adjustments screws (if it has them) and adjust it until it's perfectly square.
Comment: Regarding your last sentence, rather than say say the laser is bad, it would be more accurate to say the laser need adjusting, albeit some models are not easily adjustable.
Comment: @DrChuck - you are correct. I've fixed my answer. Thanks!
Comment: I've had a lot of success with the "Barlowed Laser collimation" - e.g. http://obsessiontelescopes.com/learning_center/collimation/index.php . It uses a laser collimator but rather neatly gets around the problem of the collimation of the laser and/or slop holding it in the focuser. It's very easy if you have a laser collimator, a spare Barlow and if your primary mirror center is marked accurately

Laser Colimator vs Cheshire eyepiece


Add Chakra to Grub (installed by Mint)

Question: I have 4x30G partitions on my SSD. I installed Mint to the first one. Mint installed grub2 with it, which recognizes Win7 on a HDD as well, so I thought I keep this boot loader. I installed Chakra to the second partition without installing grub again. After rebooting Chakra did not show up in grub menu. Can I add it somehow?
Answer: I found the solution
<code>sudo update-grub
</code>
this updated the grub and found Chakra.
Comment: nice simple solution :-)

Add Chakra to Grub (installed by Mint)


What exactly is a fortney grid transmission spectra modeling

Question: I am trying to model some exoplanets and I don't understand how this model works. Below is a link of the model. What I don't understand is how does graphing the transit depth  vs wavelength provide information. I am trying to determine the atmospheric chemistry/atmosphere/properties of planets.
https://exoctk.stsci.edu/fortney
Comment: $uhoh I just updated it. I hope it's better now
Comment: looks better, thanks!
Answer: Planets with atmospheres are not discs with hard edges, when viewed in transit across the star. The atmosphere allows light to pass through the limb of the planetary disc.
The radius within which the planet is effectively opaque to light from the star will depend on the density and composition of the atmosphere as a function of height and also the wavelength of light that it is illuminated by. This is because the opacity of the atmosphere will be much greater at wavelengths where some molecule or atom that is present has an absorption feature.
Therefore if you observe a transit at different wavelengths, you will see different transit depths, because the planet has a different effective area at different wavelengths.
For example, if the atmosphere contains lots of atomic sodium, then because sodium strongly absorbs light at 589nm, the planet is opaque to a greater radius at 589nm, and the transit depth will be bigger at 589nm than at wavelengths either side of this.
Ps. (Jonathan) Fortney is the name of the scientist who developed the grid of models.


How do you get explosive bullets in Dishonored?

Question: How do you get explosive bullets in Dishonored?
Answer: From the Wiki:

The only way to acquire explosive bullets is by purchasing them directly from Piero or black market shops, except for one case of explosive bullets that can be found in the Dishonored mission The Light at the End.
...they can only be purchased once the protagonist has found the Small-Scale Combustion Refinement blueprint.

According to the Wiki page for blueprints, you can find the blueprint that you will need during the Return to the Tower mission in the office of General Tobias or during the Flooded District inside an abandoned rail car in Central Rudshore.
Once you have the blueprint, you can buy the Explosive-Shot upgrade for 600, and this unlocks the ability to purchase them.


How to remove the "services" in front of micro services

Question: I use jhipster to generate UAA and gateway, but when I access their API interfaces through the gateway, it's like this: "http://xxx.xxx.xxx.xxx:8080/services/uaa/api/account ", I want to remove the word "services", what should I do?
Answer: Please have a look at how to write a custom RouteLocator in Spring Cloud Gateway doc and you may have also to modify GatewayResource and of course frontend code.
Also, you must understand that gateway routing should be determined on something in the incoming request or it will not work for resources which have same path in all services like swagger-ui JSON spec.


Double slit experiment query

Question: Seen as thought empty space in a vacuum is not empty is it not possible that the gluon fields that remain affect the trajetory of an electron when carrying out the double slit experiment affecting the outcome.
Comment: possible duplicate of [Double slit experiment and quarks](http://physics.stackexchange.com/q/152741/)
Comment: This question seems to be the same as your previous, with *quarks* replaced by *gluons*. It is really wholly unclear what you are asking - whether because of a language barrier, or because you are confused, I cannot say, but rest assured that an electron *has no trajectory to speak of* when doing the double slit with it. That's the whole *point* of the experiment.
Comment: surely if it hand no trajectory it wouldn't move would it?
Answer: An electron has a macroscopic trajectory from point A to point B, it can be drawn as straight line, if no electric or magnetic fields exist on the way, up to the slit with the indeterminacy of the width encompassing the slits, and from the slits to the point it hits on the screen.
When talking of the vacuum  and virtual interactions one is talking of very small dimensions with respect to the slit widths, even for electromagnetic interactions, and even smaller ones for strong interactions that are the domain of gluons and quarks. Gluons manifest at fermi distances  in scatterings, whereas the slits are at micron dimensions
If the electron had enough energy to raise interactions with gluons, which are higher order interactions, its wavelength would be so small that it would pass like a particle from one or the other slit with no interferences except, depending on the energy, of creating gluon jets  in scattering from the masses off the slit sides.
A real particle, as the electron is, to interact with a virtual particle from the vacuum would have to get energy from somewhere, as energy is conserved and an electron on a trajectory cannot change its energy unless in a very strong real field, as the gravitational field at the horizon of the black holes, which gives rise to Hawking radiation. .
So the answer is no, there is no effect from the virtual vacuum  fluctuations  in the double slit experiments.

Double slit experiment query


What is a term to describe something that is not necessary to begin with, but becomes so as a result of a non necessary choice?

Question: So basically, you have three different types of 'things' (for lack of a better term): You have that which is necessary, that which is contingent (you have a choice), and that which is necessary but only because it must be so after a contingent choice has been made. So it's necessary, but not to begin with, and is necessary in a very different way. I guess you could call that which was necessary to begin with, necessarily necessary, and that which is necessary by choice, not necessarily necessary. But of course, am sure there's a better word, or at least term, to describe this phenomenon.
Comment: You might consider [***concomitant**](http://www.dictionary.com/browse/concomitant) contingencies* (the collocation [has been used before](https://www.google.com/search?tbm=bks&q=%22concomitant+contingencies%22)). But *contingencies* aren't always a matter of choice - in fact, they're usually just "unforeseen" things that might or might not arise (by *chance*, not *choice*).
Comment: This needs context. "`Terminology` is a system of terms belonging or peculiar to a science, art, or specialized subject, nomenclature." If you just mean in general, it needs the SWR tag and an example usage. There's only two types: (un)necessary. Which one it is will be [*contingent*](https://www.google.com/search?q=contingent&ie=utf-8&oe=utf-8) on your context. Most of the answers so far are either synonyms of *contingent* or assume a specific context, i.e, medicine.
Comment: Can you edit in an example?
Answer: One of the senses of entailment applies:

entailment
...

something involved as a necessary part or consequence of something:

Long hours of work are an entailment of the job.

[Dictionary.com]
Comment: I nearly always hear this used in the form of "[the choice of] X *entails* Y".
Comment: Ah yes, entailment. I've come across this term before in my studies of logic, but I forgot it's exact meaning. Now that you've mentioned it here, it seems like a near perfect match for what am looking for.
Answer: That (originally unnecessary) thing has now become necessary because it is incidental to the other activity (choice that you made).
ODO:

incidental
ADJECTIVE
2 (incidental to) Happening as a result of (an activity):
'the ordinary risks incidental to a fireman's job'
'For instance, a charity has to refrain from political advocacy,
unless such lobbying activity is merely incidental to the charitable
purpose.'
Comment: And what's the downvoter's problem with this answer? Really surprising!
Comment: Not a downvoter, but to me, "incidental" does not imply that the thing in question is required, only that it is related. A requirement is something that MUST be present. An incidental thing is more like a side-effect.
Answer: If thing A is not an inherent requirement for an overall process P, but is a requirement if you choose to implement thing B, then A is a requisite for B.
A requisite is something required to achieve a desired goal or comply with something else. For example, if you work at Joe's pizza emporium, you can make pies, but if you want to deliver the pizzas, you need a driver's license. Having a valid driver's license is a direct requisite for being a Joe's delivery driver. Furthermore, having a valid license requires having a certain level of car insurance, so having that insurance is an indirect requisite for delivering Joe's pizzas.
Answer: A possible future condition, indirect effect or result of something (e.g. a choice) is an implication.

Definition:  something implied; a close connection.
Example: The newspapers discussed the implications of the president's election.
Answer: How about logical necessity or modus ponens?
Google search:

logical
  necessity:
  that state of things that obliges something to be as it is because no
  alternative is logically possible; a thing that logically must be so
modus
  ponens:
  the rule of logic stating that if a conditional statement ("if p then
  q ") is accepted, and the antecedent (p) holds, then the consequent
  (q) may be inferred

In the context of your question, all this means is that if A is a choice, and if A being chosen implies that B is necessarily true, then the consequence B is a necessary result of the choice A.
Answer: LATENT
Fuel, as gasoil or gasoline or alcohol, has heat latent energy waiting for pressure or spark to start.
Some people in special situations their true personalities or talents show up, that personality or that talent was in a latent state.
From Merriam Webster Dictionary:

present and capable of emerging or developing but not now visible, obvious, active, or symptomatic
Answer: Depending on your specific meaning, here's two phrases that may or may not apply:
"Mission creep" -- a military term referring to the inevitable broadening of the scope of the initial mission once boots are on the ground.
"Inheritable error" -- you want to go to the store to buy milk, but you can't find your key, then you realize your husband accidentally took your keys with him that morning so you go to call him, but your phone is out of battery, so you go to charge it, but you find your dog has chewed on your charger and destroyed it, and in doing so broke a tooth, so now you have to, by necessity, a) go to the vet, b) buy a new cell phone charger, c) charge your phone, d) divorce your husband... e) and you still haven't gotten any milk.
Answer: Your description the mechanism by which the the thing becomes necessary is very vague. However if the choice that led to the thing becoming necessary was the very choice to actually use the thing in the first place, the term addictive comes to mind.


Problem with simulation of the desired shape of the signal

Question: I am trying to generate a signal with specific frequency and shape. I have accomplished to get a time domain signal with the specified frequency, however the shape does not match. Is there any method to get the desired shape. Will phase be any helpful?
Comment: what kind of shape do you want/ do you suspect. What type of signal (audio?) and software do you have.
Comment: Are you measuring or are you creating a signal before measuring
Comment: I am trying to simulate a signal. I want it  to have a specific shape (ex: square) and also to have some specified freq( ex: 1 hz and 2 hz). I have got a signal of the specified freq but the shape is not square. I am using MATLAB
Answer: For a square wave as used in your example phase don't do anything.
Since the fourrier series is just based on a sine wave without phase.
The fourrier series are:
$$
S_n (x) = \frac{a_0}{2}+ \sum_{n=1}^{N} A_n \cdot \sin (\frac{2 \pi \cdot n \cdot x}{P}) \qquad \text{for integer } N \geq 1
$$
Since the square wave have only the odd frequencies. you can choose for the sinewaves: 1, 3, 5, 7, 9, 11, 13 ,...
For other functions it is different. In that case you have both sine and cosine signals. Combination of both give as result the phase.
if you have an series of 7 or 8 frequencies it is allready close to a square wave.
Comment: Whether the Fourier series only has sine or cosine (or both) components only depends on the signal being an odd or an even function or neither of the two (plus possibly a constant). So you can easily have a square wave with only cosine components or with sine and cosine components, depending on where you define the point $t=0$. For this reason it's a bit misleading to believe that 'a square wave' only has sine components as its Fourier series. That is just a consequence of how you defined it w.r.t. the point $t=0$.


Is the second diffraction order at different wavelength?

Question: If a monochromatic laser light of wavelength $\lambda$ is incident on a diffraction grating of period $A$, then does the second ($m$=2) diffraction orders have same or different $\lambda$? From the diffraction equation I see the wavelength, order and angle all variables so am not sure which will change.
Answer: The diffraction grating doesn't produce any output light with any wavelength that isn't present in the incoming beam.
However, you can analyze the different diffraction orders as resulting from the different spatial wavelengths present in the fourier decomposition of the transmission function of the grating.
For example, if you could make a grating whose transmission function was a perfect sinusoid as a function of position on its aperture plane, you would see only a single diffraction order. If you made a grating with a transmission function that's a perfectly periodic square function, you would get diffraction only into odd ordered beams (and the zero-order beam).


What options or solutions exist for photographers who have to use glasses?

Question: I wear prescription glasses.
They really get in the way when taking pictures.
I am aware of the diopter adjustment that some cameras have. Is this diopter aid equivalent to reading glasses?
Comment: @OlinLathrop That's been true of every camera I've ever used (which is a fairly varied bunch, including classic film cameras, all of who's viewfinders I found better than even the top tier DSLRs of today) except for a couple of waist level Med Formats. I just prefer to shoot with contacts in my eyes. It is impossible to get as close to any viewfinder with glasses on as you can get to the same viewfinder without glasses on unless you can place your eyeglass lenses flush onto your cornea (which means they are contact lenses).
Comment: You need to describe better what *"really get in the way"* means.  I take pictures with glasses on all the time and don't feel they get in the way significantly.
Comment: I wear contacts most of the time, but when trying to shoot when wearing glasses I know exactly what he means. I can't get as close to the viewfinder as I prefer.
Comment: @Michael: Then you need a better viewfinder.
Answer: Positive diopter adjustments have the same effect as reading glasses do. Negative diopter adjustments have the same effect as glasses for someone with myopia. My Canon 5D Mark II has a built-in diopter adjustment that ranges from -3 to +1. Other optional lenses are available from Canon that range from -4 to +3 diopters. If you, for instance, add an optional -2 diopter eyepiece to my 5DII, then the internal adjustment would allow a range of -5 to -1 diopters. Most DSLR camera manufacturers also offer such lenses that attach to the rear of the optical viewfinder for at least some of their cameras.
Answer: Yes, a positive diopter adjustment is exactly equal to reading glasses. The negative side is the opposite, for nearsightedness.
If the diopter built into the camera isn't sufficient, you may have some other options: see Are there any alternate eyepieces for people with glasses? for some options.
If possible, wearing contacts is really the nicest, but of course that doesn't help everyone. Of course, sometimes the reason contacts aren't an option is that the vision problem is severe astigmatism, and the diopter doesn't do anything for you there either. In that case, you may try mashing your glasses to the viewfinder anyway (I do this in a pinch, and with a viewfinder with a nice eye point it works out okay), or, you may consider adapting your photography habits to use a rear LCD screen -- DSLR "live view" or a mirrorless camera.
Comment: Well, yes and no. the "+" side of the diopter adjustment is the same as reading glasses; the "-" side is the same as distance vision glasses for myopics. In my case, all the way "-" is good without glasses (I'm severely myopic) and all the way "+" is good with (I'm also old). But that's nitpicking (as I so often do) and you're getting an up anyway.
Comment: Yeah, it's New Year's. I'll expand tomorrow. :)
Comment: I'm short sighted - so wear the opposite of reading glasses (as per    stan rogers). The dioptre adjustment works for me although im only a -2 prescription (which is relatively weak) and i have to have it all the way - side. so i dont think anyone who with a strong prescription would get away with it.

Of course the available amount of adjustment is camera dependent, but i have found this to be the case on all of my Nikons.
Comment: I have fairly severe astigmatism and wear Rigid Gas Permeable (RGP) contact lenses that correct my astigmatism much better than any eyeglasses do. They do so because the surface of the lenses are spherical and the space between the back of the lens and the cornea is filled by tears on the eye that are roughly the same density/diffraction index as the material the lenses are made of.
Comment: @MichaelClark "Severe" was probably the wrong word. I have _slight_ astigmatism, and my glasses correct for it but my contacts don't, because it would have been more expensive. I suppose a rewording of the post is in order.
Comment: Yes, RGPs are more expensive up front than soft contacts, they take more acclimation before you get used to them, and some wearers never get truly comfortable with them. But they also last for years. Although I probably shouldn't have, I once went over ten years before replacing a pair.
Answer: I wear glasses too, but don't find it much of a problem.
If you don't have much astigmatism and your correction is not too extreme, you could adjust the focus of the viewfinder to your uncorrected eye.  This is usually called something like a "diopter" setting.  However, then you won't be able to see the scene properly when not looking thru the camera.  I keep my glasses on, which correct my vision for distance viewing.  Camera viewfinders are usually adjusted for distance viewing too (the image appears at infinity), so there is no problem.
About the only real issue with glasses is that you can't get your eye as close to the viewfinder.  You need a viewfinder with a more narrow view angle so that all of it can be seen with the eye back a bit.  Camera manufacturers are well aware of this.  Nikon used to have options for "high eyepoint", but nowadays most cameras come that way standard.  It doesn't really detract from using the camer without glasses.
Comment: Are you saying that using diopter the image would look like the focus has been set to infinity?
Comment: @ange: There is no such thing as *"the diopter"*.  In general, the optics of viewfinders are such that the image in the viewfinder appears at inifinity to your eye.  In other words, your eye has to focus as it would looking at distance objects to see the viewfinder image clearly.  This has nothing to do with how the main lens is focused or how close or far the subject is in the actual picture.  Some viewfinders have a focus adjustment, sometimes calibrated in diopter, that changes the focus of the viewfinder as if you were putting different glasses between your eye and the viewfinder eyepiece.
Answer: My solution to glasses getting in the way of using the camera was to eventually change my glasses. Instead of ultra-light titanium wire frames I now wear heavier and stiffer metal frames that sit slightly closer to my face, and have smaller (but still quite practical) lenses. Not only is it now easier to see the information in the viewfinder, my glasses are less likely to be knocked askew by contact with an errant eyepiece.
Answer: One thing I did was to remove the little rectangular rubber part around the viewfinder (on my Canon DSLR bodies. I assume other manufacturers have something similar). This lets me jam my eyeglass-covered face a little bit closer to the viewfinder, so that I can see more of the viewfinder. It's not a total solution but it's an improvement.