Alternatives for Cygwin

Question: Are there any command-line interface for Microsoft Windows other than cygwin. Currently, I am using cygwin but there are some commands that do not work as they are supposed to work on linux
Comment: which commands do not work?
Comment: -1 | For you did not even care to specify any command which allegedly does not work.
Comment: it's a reasonable question; cygwin is not an OS, so there are obvious (and not-so-obvious) differences, as anyone who has used both knows ( https://cygwin.com/cygwin-ug-net/using-effectively.html ). WSL is an alternative, but has its own issues ( https://superuser.com/questions/1119886/is-there-reason-to-use-cygwin-over-bash-on-ubuntu-on-windows-10 ) or git bash for windows, which is limited, but useful of course for git ( https://superuser.com/questions/1053633/what-is-git-bash-for-windows-anyway and https://superuser.com/questions/1191805/can-git-bash-and-cygwin-shell-do-the-same-things )
Answer: I use Swan which is Cygwin, but is much more organised and behaves just like a Linux OS.
Comment: @roaima Swan installs it self like a Linux System in C:\ProgramData\Swan which is mounted as root and the the users HOME folder is mounted at $USERNAME/AppData/Swan which cannot be accessed by other users (unless it's an admin) which is a really neat feature, almost like a Linux OS, I really recommend that you try Swan for yourself, it's not that big of a install
Comment: By "_behaves just like a Linux OS_" do you mean "_has a GUI just like a Linux OS_"? From the outside I can't see that Swan offers anything much more than that, and personally I don't really have a problem with Cygwin's command-line behaviour. Not complaining, just curious.
Comment: +1 for swan. As a long time cygwin user (but my main OS is Unix/Linux), I appreciate that swan has a decent command-line interface to the cygwin package manager (and decent terminal, albeit as always w/ cygwin-on-windows, some gotchas & differences to work-around.) Kind of like babun used to do, before it was seemingly abandoned.
Comment: Swan appears to be dead. The website cannot be reached and there haven't been any commits to the project for the last eight years.
Answer: You could use the Windows Subsystem for Linux instead; that solves a number of Cygwin's issues.
Comment: The subsystem has its own set of problems but is great for command line only applications, I feel that [Swan](http://www.starlig.ht/) although the same Cygwin under the hood, is much better.
Answer: If you are not content with Cygwin, you can try one of the following. These are more or less based on cygwin, but the behaviour and features are a bit different:

MSYS2. "At its core is an independent rewrite of MSYS, based on
modern Cygwin (POSIX compatibility layer) and MinGW-w64 with the aim
of better interoperability with native Windows software. It provides
a bash shell, Autotools, revision control systems and the like for
building native Windows applications using MinGW-w64 toolchains." -
Unlike cygwin, this has built-in package manager pacman (like Arch Linux)
Git bash for windows - It supports rather basic commands, but it
might be enough for you.
MobaXterm - basically an interface for Cygwin, but has it's own
package manager and it's quite well integrated with Windows shell. It comes with X server, tabbed SSH and other tools. Full version is paid, but you can do quite many things with the basic version.

Alternatives for Cygwin


Is a 3h 30m layover between LHR and LTN enough?

Question: I am flying from New York, making a three and a half hour stopover in London. I'm landing in Heathrow while taking off from Luton. Is three and a half hours enough for this transfer?
Comment: Please use correct grammar and punctuation when posting on Travel SE.
Comment: Why the downvotes, people?
Comment: Some clarification questions which may affect things a little: where is the second flight to (I assume within Europe?)? Are you flying on one ticket or two? What is the frequency of flights to that destination from LTN, or more importantly if you had to rebook, when is the next flight? What would be the cost of an additional flight from LTN to that destination if you had to rebook?
Comment: @martin smith suggests renting a car. Is there any chance you've booked through BA? They have discounted rental cars for their customers that you can pick up in Heathrow and most likely drop off in Luton.
Answer: On two tickets - no way. If you suffer any delays at all, you'll miss the checkin deadline for the onward flight, and you'll have to buy a brand new ticket. It's just too tight
On one ticket, if you miss the second flight you'll be rebooked for free, so it just depends on how long you'd have to wait for the next flight and how much of an issue it'll be for you
When you land, you need to go through immigration, collect your bags (bags can't be through-checked between airports), clear immigration, then get to the bus or train or tube.
In terms of how to get from one to the other, you have four options:

National Express bus - coaches every 30-60 minutes, journey time of about an hour
Tube (Piccadilly line) to Kings Cross St Pancras, train to Luton Airport Parkway, then bus up the hill to the airport - 1 hour for tube then 30-60 minutes for train+bus
Train (Heathrow Express) to Paddington, tube to Kings Cross St Pancras, train to Luton Airport Parkway, then bus up the hill to the airport - 40 minutes to Kings Cross, then 30-60 mins for train+bus
Pre-booked minicab - 40-45 minutes drive assuming no bad traffic

Given that, I'd suggest the bus, though the minicab option is there if you don't mind paying a lot more
If you're an EU passport holder, you can probably get from the plane to the airport exit in 30-40 minutes. Then you need to get to the Central Bus Station in the middle of Terminals T2 and T3, that's a 5-10 minute walk from T2 and T3, or about 15 minutes from T4 or T5 via tube/train transfer. Next, you need to wait for the bus. Then about an hour on the bus to Luton, then checkin again there.
Don't take a black cab, the price will be crazy. You could pre-book a minicab or similar, but it'll cost many times more than the bus, and won't save that much time. If traffic on the M25/M1 is bad, you'd miss the onward flight either way, and if not the bus should get you there. If you're worried about a 10-15 minute difference, then you shouldn't be booking tickets at just above the MCT, and need to pick a safer itinerary!
Either way, that journey is most of your transit time there, so any noticable delay (flight, immigration, traffic) and you'll miss the checkin deadline for the onward flight. On two tickets you're screwed at this point, on one ticket you'll have to get re-booked and wait for the next available flight
Comment: It's worse than that. The National Express bus is only every 30-60 minutes so, on average, you'll have to spend 15-30 minutes sitting around waiting for that to leave.
Comment: Or private hire car would probably be about £50 from a quick Google and should be quicker journey time with no need to wait for a scheduled departure time.
Comment: @MartinSmith This might actually be a good suggestion. According to Google Maps, Heathrow to Luton takes about 36 minutes by car via the M25 and M1. I was sceptical at first given that London has a reputation for heavy traffic, but depending on when they arrive, it might be an option.
Comment: I would definitely take a car and I think you are pessimistic. The official minimum connect time between LHR and LTN is 3 hours 25 minutes. Most of the time the traveller will make the connection. It depends whether she is willing to take the risk. London traffic tends to be bad on London, but Heathrow barely qualifies and Luton is 20 miles from London.
Comment: @Calchas "Heathrow barely qualifies" - I take it you don't travel on that section of the M25 often, then? Between 7-10am and 4-7pm it's typically fairly horrendous. Outside of these times it's usually fine. I'd very definitely echo the `On two tickets yes, one ticket no` advice: London transportation is far too unpredictable to risk it on one ticket
Comment: @JonStory: Are you sure you haven't switched "two tickets" and "one ticket" around there?
Answer: This is not a job for public transport. All transport options involve going into the city and back out again. Both airports are outside the M25 on the same side!
Arrange for a taxi, it will cost around £50. You can pre-book one online to have it there waiting for you.
It can be done. You will be at the mercy of the traffic. As someone who has lived in London my entire life, I would not book these tickets. The money saved by booking a cheaper flight from Luton is unlikely to outweigh the additional stress it will cause.
*edit*
It has been pointed out that National Express coach does go directly around the M25, which would make it the only viable public transport option. The price is £22.50 (correct Dec 2015). An independent travellers guide has a dedicated page to this coach journey, and provides this statement:

"The absolute minimum time with no contingency between flights that
  you should contemplate making a transfer between Heathrow and Luton is
  4.5 hours."
Comment: Actually I think the National Express coach does goes direct via the motorways without going near central London - but still, even the motorways around London are notorious for often getting snarled up. But I agree 100% with the "additional stress" comment
Comment: £50 seems very low for a black cab. The OP might want info on what taxi to book (presumably Addison Lee or similar?) to get this kind of price.
Comment: OP will need to provide details of date, time, terminal, before I can accurately google an actual taxi quote on their behalf.
Comment: Googling "heathrow to luton taxi" one of the sponsored ads I see says "from £49" but maybe that is only at quite rare times.
Comment: @user568458 oops you are right, I will have to work out how to adjust my answer.
Answer: The official minimum connect time between Heathrow and Luton airports is 3 hours 25 minutes. This is the shortest time the airlines will allow if you book connecting flights on one ticket.
It suggests your timing is tight but usually doable.
Personally I think if this went smoothly, if you have an electronic EU passport, no bags and a reliable taxi firm waiting, you could be airside again at Luton in less than 90 minutes. But things do go wrong with air travel and that two hour contingency can disappear fast.
I suspect you are connecting across separate tickets because Luton is a low cost airport. Therefore you are taking the risk of being stuck there or having to buy a replacement ticket. If you are happy with that, book the tickets. If not, find another route.
Comment: "that two hour contingency can disappear fast" -- in two hours, to be precise ;-)
Answer: A lot of pessimists here. You'll make it 95% of the time using a cab. It just depends on how serious the 5% consequences are.
Comment: Consider that a flight from New York is more prone to delay than continental flights, though. And how bad actually missing the next flight is.


Trajectory following- What if the robot joint motor are not able to keep up with the generated trajectory?

Question: I want my robot manipulator to follow a user-defined path. Based on the waypoints given as input and the velocity and acceleration limits of the joint motors, I generate a trajectory.
At every time step (say 2ms), I send the joint motor controller the reference position, velocity and acceleration. But my robot's joint motors are not able to keep up with the reference command.
How can I update my generated trajectory, so as to ensure the robot moves along the user-defined path?
Thanks!
Answer: Great question!
In practice, you don't specify a dense trajectory for the arm necessarily
Instead, you should move the arm between "safe" positions before it moves to the point where it interacts with parts. Most robotic arms are designed to be controlled in this way. If you are trying to control the exact path of the end effector, then you are trying to do essentially velocity control, which requires force-torque control of the arm (usually). That's a harder optimization problem and still requires a good model as described below.
But trajectory control is more fun
We can add a lot of similar situations to this: What if I'm slightly wrong about the model of how the manipulator moves between waypoints, and the trajectory is not follow-able? Or what if the world changes slightly and my trajectory is now invalid? etc, etc.
At a very low technical level, you should change the time step in your trajectory planning to accommodate motions the arm can actually follow. This means allowing sufficient dwell time at each waypoint to ensure the arm can arrive at the points. For "dense" trajectories with lots of waypoints, this is hard. Without a near-perfect model of how the arm converges to a point, how can you predict how long it will take to reach a point when planning a trajectory?
Usually, at the highest level, you can just replan the trajectory based on the current state of the world. Then, you issue the "next" waypoint as the carrot for the arm to follow. This is called receding horizon control, which is a common way to implement model-predictive control
Comment: Thanks for the suggestion of receding horizon control. I'll try this. But I'm concerned about the computation time for recomputing of trajectory in receding horzon control. I will read more about it.

The motor control i use is not model-based. it is just a PID control with feedforward and gain scheduling. I know the control needs improvement. But like you wrote the generated trajectory can become invalid for other reasons too.


How do I maintain an online users list?

Question: In a multiplayer JavaScript game client, is it a good idea to poll the server periodically to refresh online user list, or keep track of joined/left users? Is there a better option?
Answer: A combination of both strategies would likely yield the best results. Just keeping track of when user join/leave might not account for situations where the user is unexpectedly disconnected. A periodic poll would likely have to happen too often to get reasonably updated list of players joining and leaving.
So, update the list when a player joins or leaves and poll less periodically.
Answer: It depends is network traffic efficiency really important to you.
If it is not you might have three actions in your server:

connect - which will add user to a server list
disconnect - which will delete user for a server list
poll - which will periodically check all users alive status (simple ping with client app)

More complex but also better way is to use timers. Every user will have a separate timer when he joins. When the timer runs out, server will poll for his status.

if he is alive server reset timer
if he is not responding server will delete him from user list

It won`t generate as big lag as polling all users at once.
Edit:
actions for the client

connect
disconnect
"ping" response

In other words, you are not polling server at all until server will ask you for alive status.
Comment: I am asking for the client, not the server side. My server side is a third party api.

How do I maintain an online users list?


Push down automata acceptance by Empty stack and final state

Question: I have a very basic question.  Can we have a PDA which can accept a string by  both final states and empty stack?
Can the same PDA accept by the two modes simultaneously ? If there are final states for acceptance and in addition to that at some point in time the input string is read completely and simultaneously the stack is empty but the state is non-final. Will it be accepted in that case ?
Answer: Yes, that is possible. If you start with one that accepts by final state, you can change that one into an automayon that accepts by final state and empty stack as follows.
First create a new final state $f$. From every old final state have an epsilon transition to the new state $f$. Add transitions to $f$ that empty the stack.
It seems best to keep the old final states. A computation of the old automaton might end in one of the old final states with an empty stack, in which case it should be accepted, but we have no contents of the stack, so we cannot move to $f$.
Comment: I meant to ask can we have the same PDA accept by the two modes simultaneously ? Like there are final states and at some point of time the input string is read completely and simultaneously the stack is empty but the state is non-final.
Comment: Do you mean a construction where both modes give the same language? Where computations of a PDA move to a final state and empty the stack simultaneously? (And not one without the other?)


Document classification using convolutional neural network

Question: I'm trying to use CNN (convolutional neural network) to classify documents. CNN for short text/sentences has been studied in many papers. However, it seems that no papers have used CNN for long text or document.
My problem is that there are too many features from a document. In my dataset, each document has more than 1000 tokens/words. To feed each example to a CNN, I convert each document into a matrix by using word2vec or glove resulting a big matrix. For each matrix, the height is the length of the document, and the width is the size of word embedding vector. My dataset has more than 9000 examples and it takes a lot of time to train the network (a whole week) which makes it difficult to fine-tune parameters.

Another feature extracting method is to use one-hot vector for each word, but this will create very sparse matrices. And of course, this method even takes more time to train than the previous method.

So is there a better method for extracting features without creating large input matrices?
 And how should we handle variable length of documents? Currently, I add special strings to make document have the same length, but I don't think it's a good solution.
Comment: Does using TfIdf vectorizer seem suitable? Maybe in combination with word2vec to leave only top x words for each document?
Comment: Well, I don't know what Tfldf is. I'm going to check it to see if it works. Thank you
Comment: http://scikit-learn.org/stable/modules/feature_extraction.html#tfidf-term-weighting here for example
Comment: I just check it and I think it doesn't help me. Basically, that helper class creates a matrix for a set of documents. Each row vector (binary or wordcount) in the matrix corresponds to a document, but for CNN, we need a matrix for each document.
Comment: The point was to leave only x non-trivial words per document ranked by their TfIdf. Then use your original encoding to build document matrices. Not sure if this two step approach idea came across.
Comment: Have you tried doc2vec instead?
Comment: This paper ["Chargrid: Towards Understanding 2D Documents"](https://arxiv.org/abs/1809.08799) uses a conv net that operates on character level. ~50 channels are easier to handle, maybe that's also sufficient in your case.
Answer: You could reduce the length of your input data by representing your documents as series of sentence vectors instead of a longer series of word vectors. Doc2vec is one way to do this (each sentence would be a "document").
If you don't want to use Doc2vec, one way to create the sentence vectors would be to average the word vectors for each sentence, giving you a single vector of the same width for each sentence. This may not be as precise as some methods available through Doc2Vec but I have used it with considerable success for topic modeling.
Either way once you have your sentence vectors, line them up in sequence for each document like you're already doing for your word vectors and run then through your model. Because the sequence length for each document is shorter, your model should train more quickly than with word vectors.
By the way, this method could work when scaled up or down to meet your accuracy and speed needs. (e.g. if your CNN still trains too slowly with sentence vectors, you can create paragraph vectors instead).
One way to handle documents of different length is through padding. Your document sequences should all be equal in length to your longest document. So if your longest document is 400 sentences then all document sequences will be 400 vectors in length. Documents shorter than the max length would be padded with vectors filled with zeros.
Comment: In speech processing, some people order the sequences based on its length so that sequence with similar length will be in the same batch. This might work for text sequence.
Comment: Interesting idea. I'll try it :)
Comment: May I ask a question? How can I deal with documents that with significantly different lengths(5 sentences/doc, 500 sentences/doc) even I represent them in sentence vectors ? Padding here seems weird...
Answer: You could use region embeddings. Rather than converting individual "tokens" to vectors you could use a strategy to convert regions of text to vectors. This approach is used here.
If you're not limited to CNN, you could use a hierarchical attention models such as this one where you have a pipeline of this kind:
<code>word vectors (combined into) sentence vectors (combined into) final document vector
</code>
Note that, with this method, you will still have to convert all the word vectors to embeddings, but not all at once.
To handle documents of different lengths, padding/cutting is the only solution so far.
Finally, to increase speed, you could try to reduce the dimension of the text by only including important sections (maybe only the beginning of the document is sufficient to have good classification accuracy)
Comment: Thanks for your reference link. The region embedding is interesting.
Concerning variable-sized document, as mentioned in this article https://arxiv.org/abs/1412.1058 (same author), we can use multiple pooling units instead of padding/cutting.


Decompress Tile Package

Question: I'm curious if it's possible to decompress a 10.1 tile package (.tpk) into a different format such as the cache bundle format.
Answer: Tile packages are just normal zip files which contain the images in a "bundle" format along with metadata in more familiar formats.
The bundle format is proprietary and undocumented.  Some details including initial code sample are available on the ArcGIS forums.

Decompress Tile Package


How should I remedy bowed floor joists?

Question: My house is 24'x24', (2 story), kitchen (main floor) has approx. 5 "bowed-up" floor joists in a row in the middle. I want to change all cabinetry, so while removed, how to "safely" remedy this bowed floor? I have access to the 2"x8" floor joists from unfinished basement. Built in late '78, main beam is wood. Would also like to know what causes this. Can I "sandwich" the bowed floor joists between 2 others (adhesive and bolts), then "shave" the top of the bowed joists in the middle? Seeking advice...
Comment: Because of the way lumber is graded, reducing the depth of structural members by shaving or ripping or other means is prohibited by most model building codes. In addition, there is inadequate information to determine what size members are required to support the floor based on the information provided.
Comment: @benrudgers - that is right but you can sister (with same type or greater dimensional lumber) then shave.  What we have done to a few old houses in our area.  This is one of my least favorite jobs.
Comment: Does "bowed-up" mean the joist sagged in the middle?  Or could it be that it was held high in the middle and the ends were pushed down?
Answer: You'll end up getting different answers from different people.  Some folks actually will tell you to notch the bottom of the joist to let it sag back down before sistering the joist.  But IMHO, it would be best to know the cause and effect before making any permanent structural changes like this.
I had a similar problem (high joists in poorly constructed house, not bowed) and ended up just raising the other joists to be level with the high ones.  No structural changes, just shims on top of low joists.  Resulting subfloor was dead flat when all was said and done.  If your joists are truly bowed up in the middle, it will be more work since you won't be able to use uniform thickness shims.  Shims on the outside will have to be thicker than in the middle....

How should I remedy bowed floor joists?


Wiring multispeed PSC motor from ceiling fan

Question: I disassembled a ceiling fan to replace seized bearings. Unfortunately the pics I took to aid re-assembly are no longer accessible and the fan is an '80s era no-brand which I can't find any info for online. I have determined this is a PSC motor with a 3-wire speed control (L-->off / L-->A / L-->B / L-->A+B), a DPDT reverse switch and a single non-polarized capacitor. The motor has 5 colored leads (red, black, grey, green, brown) and I measured resistance as follows: Black-Red=30Red-Grey=60Black-Grey=90 I'm doing my best to understand it but I'm still a little confused about how to re-connect it all. I made a diagram and took the liberty of numbering all the leads in order to aid discussion. Any help would be much appreciated - thanks!
Answer: I came up with a solution so I'm going to to go ahead and post it in case anyone else should happen upon this and find it useful.I added the 1-in, 2-out, 4-position speed switch into the diagram. The switch works by taking one input and routing it thusly:[1:  (off) | 2:A | 3:B | 4:A+B] and in this way controls speed by energizing either one part, 2 parts, or all 3 parts of the run (inner) winding (see diagram to help make sense of this).
I found conflicting information about achieving reverse (some sources said switch the polarity of the run winding, some said the start winding); I went with the start winding (the outer one) and it worked. Lastly, I found the capacitor was to be inserted in the start winding and that was straightforward enough.
With the AC input I made red Hot and blue Neutral; however it doesn't appear to me it would make any difference, other than that one way the reverse switch is up for clockwise rotation and the other it is up for counterclockwise rotation.
Comment: Thanks for the answer. I thought this was an interesting question. I guessed the  R, B, and Gry wires terminals correctly when you first posted the question and couldn't figure out the wiring for the reverse switch. Glad you got it working.


Not having a getter method in POJO does not set the values via setter method

Question: I am using org.json library for JSON parsing. I have experienced that when I have two methods say getName() and setName() and if I comment the getter method in my POJO class, the setter method also does not work .
But if i don't, it works. Why this happens? Can't we just set the value in POJO and convert to JSON string?
Comment: It might be easier to help if you were to post a [MCVE](http://www.stackoverflow.com/help/mcve) which reproduces this issue.
Answer:
Can't we just set the value in the POJO and convert to a JSON string?

If you comment out the getter method, the JSON library will no longer serialize the property, because it has no way to get the property.


Keyboard support

Question: I have a Yamaha P115 keyboard. When using the double X brace my keyboard wants to slide off as there is no stops built into the brace. How can I stop the movement before the keyboard hits the ground?
Answer:
Make sure the top tubes of the brace (the ones you place your keyboard on) are level.
If the brace is level and the keyboard still slides around, you need some high-friction padding (e.g. rubber or foam) between the tube and keyboard.

Rubber stops are fairly common on these stands:

But they're easily lost: they aren't locked in place so they'll slide off when you apply too much force.
Comment: First thing I do with any stand (mic/k'bd etc) is pop rivet the rubber/plastic endstops in place.
Answer: Use velcro tape - hook and eyes - glued on the top bars of the stand, and the matching places under the keyboard. And if the stand is to be taken out of the house, pop rivet or use adhesive on the endstops. Otherwise they will eventually escape.
I guess you mean the keyboard slides towards or away fom you. that's what the endstops are there for. If you mean it slides sideways, then a couple of strips of wood, or carpet, or rubber glued under the keyboard will stop that.
I have used foam for lagging water pipes split and slipped over the top tubes, too.
Answer: You could also fix the upper arms of the X by aparallel or diagonal line, cable or wire like clothe horse to prevent the worst case scenario:
Comment: That will stop the stand collapsing, but not stop anything on top sliding.
Answer: What about rubber bands? You could wrap some of the thick ones around the tubing on the keyboard stand to create a lot of friction. They're also free or relatively cheap.
Another option is friction tape which can be found at hardware stores.

Keyboard support


What is my chance to find a block on a TestNet ?

Question: My gethashespersec is 4806082,  on the TestNet what is my real chance to find a block ?
Comment: To answer this question I think we need to find the total hash rate of the Testnet network. I'm not sure where this information could be found.
Comment: Unlike the main network, it's not so easy to estimate the total Testnet hash rate from the difficulty and block times, because of the "difficulty drops to 1 after 20 minutes" rule.  I've been thinking about this question and I'll try to post something in the next couple days if I have time.  Of course, the hash rate of Testnet also can be expected to fluctuate much more than the main network, as people bring miners online and offline for testing.
Comment: It would be interesting to see a chart of testnet hashrate in time...
Answer: You have almost 5MH/s, so at the current difficulty = 1787.78664453 and given, that base diff for testnet is 0.5 diff for main btc network, you can put this into calculator, and you get

9 days, 6 hours

. Hope this solves your case.


Where are drona and shiva used as meters, what other meters are there similarly?

Question: I learned recently about Koorathaazhvar and Kulothunga Chola's apparent argument, although I'm not interested in the context it was used, I'm curious about the question, as what and when are these meters(drona, shiva)used, and what other such meters are there?
Comment: This question is primarily associated with songs and poetry and ragas  and little to do  with Hinduism. So am not sure if this is valid question for he site or not.
Comment: Does the poster  mean "measure" when the says "meter"?
Comment: This is a linguistic question and should be closed @SwiftPushkar
Answer: The measurements Drona appear in many ancient texts. Dronacharya, who is the teacher of Kauravas and Pandavas was named after a bucket or a wooden vessel.
When Krimikanta Chola asks to sign a document saying there is no one higher than Shiva, Kurathalzhwan adds a line but Drona is higher. Here, Koorathazhwan was meaning the measurements.
There are certain measurements given in an ancient Ayurveda texts named Ṣoḍaśāṅgahṛdayam. From wisdomlib.org

Guñjā (Raktikā) = 1 seed of Guñjā
  8 Raktikā = 1 Māṣa (1 gram)
  10 Māṣa = 1 Karṣa (10 grams)
  2 Karṣa = 1 Śukti (20 grams)
  2 Śukti = 1 Pala (40 grams)
  2 Pala = 1 Prasṛta (80 grams)
  2 Prasṛta = 1 Kuḍava (Añjali) (160 grams)
  2 Kuḍava = 1 Śarāva (320 grams)
  2 Śarāva = 1 Prastha (640 grams)
  4 Prastha = 1 Āḍhaka (Pātra) (2.56 kilograms)
4 Āḍhaka = 1 Droṇa (10.24 kilograms)
  4 Droṇa = 1 Droṇī (40.96 kilograms)
  100 Pala = 1 Tulā (4 kilograms).

When it comes to measurement named Shiva, it is lot smaller than Drona. It corresponds to a measurement of a peg. Monier Williams Dictionary gives one of the many definitions. The related one to measurements is

a peg, L.  [ID=217521]

But I couldn't find exactly in which text this measurement is given.
Comment: @SK It is not a hate speech. It is one of the names I have not gone into details on what happened in the conversation of Koorathazhwan and Chozha king. We should give context of what is the answer about. Apparently, some users misunderstood what OP said in the question by meter. OP meant measurement only.
Comment: @SK Hate speech against a king who murdered 2 pious, learned Brahmanas? What's next, hate speech against Hitler, against Stalin, by calling them evil?
Comment: @Naren You are welcome. You may upvote questions and answers you have found helpful. If my answer has addressed your queries, you can click on tick mark below the answer. Also take a [tour] of our site.
Comment: Although the questioner has said explicitly that he is not interested in the Siva-hatred fairy tale (that has no historical basis) this poster has put it in.
Comment: "krimikanta chola" is hate speech against a great historical king.


PIC - How to skirt around low maximum ADC input impedance?

Question: Reading a 9V battery on a PIC is nothing new. The most simple and straightforward way is with a voltage divider. I'd like to keep the divider resistances cranked up into the hundreds of kohms so I'm not killing my battery unnecessarily, however I looked at the datasheet for the PIC18F4550 and the max "recommended" analog input impedance is 2.5kohms. This means I can stick 2 5Ks for my divider, but 900uA is a lot to waste on just checking the battery. What can I do to my design (passively) to minimize battery drain? I've considered active solutions such as a software controlled pfet or a buffer, but board space and budget are a bit of a luxury, so I'll only do it if I have to. I'm also wondering if I'm I being concerned over nothing.
Comment: I just find this post during my google search. Just for saying that you have answered my question and given me a lot of help !!! My atempt to read ADC with my PIC18 was blocked because the value read by the MCU allways varie... I put the RC suggested by Alex and all the probleme go out !! Thanks a lot ! PS: Excuse me for my english, I am french.
Answer: The reason the ADC needs a low source impedance is because it has a switched capacitor input.  Basically, whenever the ADC 'samples' the voltage on the pin, a small capacitor is connected, charged up, and then disconnected.  If the impedance is too large, charging the capacitor up will draw enough current to create a voltage drop large enough to affect the reading.
If you need to read a high speed signal, the best option is to add an amplifier of some sort to provide a low source impedance to the ADC.  However, if you are looking at a relatively slow signal there are a couple of other options.
One solution to this is to increase the sample time - the length of time the capacitor is connected to the pin.  The chip usually has a limit on how long this time can be, though.
Alternatively, you can add a decent sized capacitor in parallel with the ADC input pin.  This will decrease the amount of droop that occurs when the ADC sampling capacitor charges up as most of its charge will be drawn from the capacitor instead of through the resistor.
Comment: Capacitor is the way to go. ADC specifies a source _impedance_ not resistance. Convert its sampling time to a frequency, and use a cap with impedance much lower at that frequency.
Answer: There are about 4 ways of connecting a voltage divider to an A/D and dealing with max input impedance requirement.

Use small enough resistor.  This is what the O.P. is already doing.
Put an OpAmp buffer between the divider and A/D input.  OpAmp should have high input impedance and low output impedance.  [As already mentioned by Alex.]
Use a larger resistor and add a capacitor from the analog input to ground.  [As already mentioned by Alex.]  The capacitor should be mush larger than the one in sample and hold.  You will be inadvertently making an RC filter, but this still works if the signal is slow.  A combination of 10kΩ and 0.1μF worked well for me.
[last but not least]  Switch off the voltage divider with a MOSFET switch, and use relatively small resistors.  This was you can eliminate the leakage pretty much completely when you are not measuring.  This is a common technique for battery measurement.

Replace R1 and R2 with the values you need.  The schematic was originally posted in this thread.
Comment: @Bitrex  Suppose, you make a low-side switch out of a digital output pin like you're describing.  +9V is applied to the top of the voltage divider.  When the low-side switch pin is driven low, everything is fine.  When you set it to high-Z, +9V will appear on the A/D pin and on the switch pin too.  PIC pins are not rated for +9V.
Comment: Why not just connect the voltage divider to a pin on the PIC? Drive the pin low to sample, set High-Z to disconnect.
Comment: Oops, for some reason I missed the "9V" requirement!
Comment: An idea that could work with the above scheme that saves a MOSFET is driving the PNP in the above image directly from the same pin the resistor divider is connected to; drive to 0 to measure, and to Vss to shut off.  With appropriate selection of pullup/pulldown resistors for the pfet, this will work so long as the 9 volt battery voltage doesn't drop low enough to forward bias the fet's body diode.
Answer: Bitrex's idea would work if the PIC digital pin was configured as "open drain" then clamped to 2.7V with a zener to protect it from the 9V.
To turn it "ON" and "OFF" initialize the pin by writing a logic low to it (and leave it there) then turn the pin "ON" and "OFF" by writing to the TRIS latch which will cause the pin to be either a logic low or high z respectively.
The pin will switch from 0 to 2.7V which should be enough to drive a low gate threshold MOSFET.


The Speed Of Time - Does That Phrase Make Sense

Question: We often say that "time seems to be going very fast" or "it feels like the time just sped up".  When you think about it, do these phrases make any sense? Isn't our definition of speed "how far some distance passes in a certain amount of time"? Doesn't that make it incorrect to say "the speed of time", because time does not travel any distance? Or does it?
Comment: I'd note that the way you've written this question, it's very clearly a matter of language, not of science. It would get a reasonably different response on [physics.SE].
Comment: I'm voting to close this question as off-topic because it elicits discussion about physics rather than language.
Comment: It's not clear what you're asking here, which is evident in the largely physics-based discussion in the questions and comments below.  It's obvious to everyone, including yourself I believe, that these are figures of speech and so incorrect, technically, like all figures of speech, which by definition are not literally true.
Comment: We are constantly travelling forward through time at a rate of one second per second.
Comment: It makes as much sense as speaking of the sun rising. :P  Metaphors aren't known for their scientific accuracy, but the perception is near-universal enough that a phrase to describe it was inevitable.
Comment: When you say _"it feels like the time just sped up"_, you're not describing **reality**, you're describing what you **perceive** or **experience**. Similarly, consider _"I have a medical condition. When I touch water, it feels like I'm touching fire"_. The speaker isn't claiming that he is _actually_ touching fire, he's claiming that it feels **as if** he was touching fire.
Comment: As linked elsewhere: en.wikipedia.org/wiki/Time_perception How things "seem" and "feel" are governed by the firing of trillions of synapses through billions of neurons. These phrases are indicative of actual phenomenon occurring that govern how the speaker perceives the passing of time. It has a basis in neuroscience/biology/chemistry/physics - in the neural networks of us humans, not in the passing of time itself.
Comment: I'm voting to close this question. It's either primarily opinion-based ("these figures of speech suck, am I right?") or too broad/off-topic ("what is the nature of time?").
Comment: @PeterOlson - Only if you read too much into it.
Answer:
Isn't our definition of speed "how far some distance passes in a
  certain amount of time"? Doesn't that make it incorrect to say "the
  speed of  time", because time does not travel any distance?

No.
For example, time is often defined operationally in high precision clocks with reference to the rate at which radioactive elements decay or change electromagnetic states without moving any measurable distance.
Distance per time is the definition of speed which is related to time (velocity is speed associated with a particular direction of travel), but is not by any means the only way or most fundamental way to define time.
In general relativity, time is a dimension similar in many respects to length. It is a form of distance rather than something defined by distance.

When you think about it, do these phrases make any sense? Or does it?

The phrase refers to the psychological perception of time, rather than to the physical reality. Sometimes time perceptually seems to go faster or slower in particular circumstances, even when the rate at which it passes doesn't actually change.
There are circumstances when time for one observer can slow down as a physical matter relative to the way that it is experienced by other observers as a result of special relativity. Thus, an observer who spends a long time on a round trip at close to the speed of light will have experienced less physical time elapse than one who stayed at the point of origin/destination the whole time. So, the concept of time flowing at different rates for different people is not a nonsensical one. But, that is not what the expressions you reference are referring to (at least historically).
Comment: @bob the terms "speed" and the term "rate" are often used interchangeably, so yes, it doe make sense.
Comment: Your physics take has an engineering side too - whenever designing or working with systems that have to synchronize time, you're dealing with units like "seconds per second" measuring elapsed time as reported by one clock over a given interval as measured by another clock.
Comment: @R.. Indeed, the broad definition of "speed" may actually be a bit narrower than "rate" but more like "rate of something per unit of time."
Comment: I would like to note that I do understand the concept of time feeling faster or slower. I also have read enough about physics to know that times is a dimension and in many ways similar to space. However, first of all, time being similar to space does not allow to travel through space in a certain amount of time. Second of all, I am not asking whether this phrase makes sense in terms of physics (though that would be just as interesting a question). I am asking whether it would make more sense, in language terms, to say something like "the rate of time" or "less time seemed to pass".
Comment: @bob Are you claiming that "less time seemed to pass" makes no sense, i.e. you don't know what it means?
Answer: Velocity (speed) is distance travelled divided by the duration of time spent travelling. V = d/t
What distance does time traverse that can be measured in other terms than duration itself?
If you use t for d, you get V = t/t.
This means that the speed of time is 1 second per second.
Is this a helpful value?
Or are you talking about perceived duration versus measured duration?
If, on the other hand, you're using time metaphorically, then there are other possibilities,
like the   Time Is Money metaphor theme.
Answer: It may be apocryphal, but there's an Einstein quote,

A minute with your hand on a hot stove feels like an hour. An hour
  with a beautiful woman feels like a minute. That's relativity.
Comment: @bob: Perception is not always the same as objective truth. Einstein's quote was about the _perception_ of the passing of time; and the examples you provided are too.
Comment: Yet, if you look carefully, Einstein did not say anything about the "speed" of time.
Comment: @bob, actually yes he did. The actual quotation ends with ["... That's relativity."](https://www.goodreads.com/quotes/370132-put-your-hand-on-a-hot-stove-for-a-minute) He is specifically talking about "the speed of time". So to join *physics* with the *art of language*, turn to Einstein.
Comment: @Octopus - much thanks. I recalled the quote from memory, and failed to include the last words. Just edited in, thanks to your note.
Answer: Such expressions as 'time flies' are purely subjective and are metaphors. I am neither qualified nor keen to stray into the realm of Physics but at least I can say that time is a state, without facing ostracization from too many of the places I
frequent.
Within the state of time and within the state of space, there is movement; some fast, some slow. And all the movements are relative, one to another.
My lifetime has been about twenty five thousand times as long as the fleeting moments of a mayfly's existence, and the tortoise in next door's garden could well outlive me.
But the expressions you use above, subjective as they are, deserve to be stated and should not be suppressed for merely scientific reasons.
Comment: @bob "Does that phrase make sense?" was the question. My answer is that, subjectively and metaphorically - yes it does. But it may not be scientifically accurate in terms of quantum entanglement and relativity.
Comment: I am not saying at all that this phrase should be eliminated. I am saying that it might make more sense said in a different way.
Answer: The speed of time can be defined as the ratio between the amount of time that has passed when measured objectively, and the amount of time that seems to have passed when assessed subjectively. If three hours has passed but it seems like an instant, we say that the time went very quickly.
So it does make sense: it's a measure of how much our perceptions differ from reality.
Whether there's any scientific basis to it, of course, I can't tell. If there is then it's in the realm of psychology rather than physics.
Comment: Also in the realm of neuroscience:
https://en.wikipedia.org/wiki/Chronostasis
Answer: It absolutely makes sense, even if in a metaphorical way.
The most concrete meaning of "speed" is, as you say, distance per time. For other kinds of change per unit time, we usually say "rate" instead, but "speed" is easily understood. You can find examples of people referring to things like "the speed of temperature change" on the web, and, even if you think "speed" is not the best term, it makes sense as a term for the change in something per quantity of time.
But then you can take another metaphorical step. In a literal sense, if time is just a single thing, then change in time per change in time will always be 1. But, if there can somehow be two kinds of time, then the rate of one in terms of the other makes perfect sense. There can be "time as perceived" as compared to "time as measured", which comes up in the examples you gave. There can also be "time measured by one observer" compared to "time measured by another observer with a different velocity", which can literally be different, although time is not generally referred to has having a speed in that context.
Answer: Out of context it is difficult to say if "the speed of time" makes any sense. In your other examples "time seems..." and "it feels like..." it is clear that they express the idea that there is a subjective perception of time that differs from its (assumed) absolute nature.
My favourite expression in this category: time flies when you're having fun!
I thought that one hour had passed, but looking at the clock it was two hours. Real time went twice as fast as I thought. The speed of time was two real hours per imagined hour.
Answer: Btw, in case anyone's interested in the real speed of time, then time moves at the speed of light:  that is to say, we are all travelling from the past to the future at light speed.  This is why travelling at physical great speed makes time slow down:  we are already at the max speed for the universe, so if we want to travel in space in addition to that, we need to use some of our "time speed" to travel in that extra dimension.
Answer: The time itself to do something could be seen as an absolute. If it takes less time to do the same thing one day, that absolute time feels like it passed more rapidly; if it takes longer, that time seems like it was longer - which indeed it was.
It's only a metaphor, referencing our feeling of a period of time passing. 'Seems like months since I last saw you'. 'I'll only be a minute'. There are plenty of phrases we use referring to the passing of time that don't hold water. But we keep on using them, as they convey our thoughts quite well !
Answer: If you're sitting in a train, and you watch the trees and houses pass you, would you say they're whizzing by quickly? I would, even if I'm aware that it's the train that is moving. (Not that there's much a difference in classical kinetics.)
While it's commonly believed that it's our minds that move through time - although this isn't exactly a rigorous statement - the idioms you mention are consistent with other ways to describe similar phenomena that are just artifacts of our perception rather than "real" according to some model of physics. (Compare and contrast: how humans don't have a sense for anything we call "wet.")
Answer: Heres a thought experiment:
1) We divide a homogenous piece of radium into two equal masses.
2) We verify that their radiation is the same:
They release the same amount of radiation per second.
3) We now spin one of the pieces EXTREMELY FAST !
(To a "relativistic" speed!)
If we now measure and compare the radiation from the spinning piece of radium with its stationary twin we will find that the spinning piece is releasing less radiation per second ...
And the physical explanation for this is that the speed of time in the spinning radium is slower that in its stationary twin.
ONE SECOND PASSED INSIDE THE STATIONARY TWIN
IS OF SHORTER DURATION THAN A SECOND IN ITS SPINNING TWIN!
Comment: The querent is discussing what is essentially a psychological phenomenon, and asking whether a specific phrase is meaningful in that context; your response does not really address the question being asked. Please explain the relevance of your answer to the question, including any appropriate references; answers that are merely bare assertions can be removed.
Answer:
Isn't our definition of speed "how far some distance passes in a certain amount of time"?

Ah! There's your gaffe. A good dictionary will list multiple meanings of the word speed – some as nouns, and some as verbs. Some of these definitions will be technical:

speed (n.) Physics Distance traveled divided by the time of travel.

while others will be more figurative or metaphorical:

speed (v.) To pass quickly : The days sped by. The months have sped along.

As for the phrase you ask about – the speed of time – I wonder: What do you mean by "incorrect"? What might be incorrect on a science test could well be grammatically correct in an essay, and could even be profoundly correct in a poem. In the English language, the issue is not whether or not time travels, but how much words bend.

Our fleeting lives accelerate
In ways that are sublime
So thus the elders ruminate
And scrawl a simple rhyme
The physicists pontificate
A constant paradigm
While linguists pause to estimate
The velocity of time

If this wasn't the answer you wanted, then (as your first commenter said) you've probably asked on the wrong Exchange.


Arduino Nano Midi to cv convertor interesting issue

Question: I created the circuit in this schematic on protoboard,

and the code,
https://github.com/elkayem/midi2cv
I use a dual opamp and a single dac, because i only need note and velocity.
The opto i use is, H11L1
It works but has a strange issue that i can not figure out.
The author says the code supports midi notes from 21 to 108.
When I send midi notes to test the device,
(Arduino powered with +12, TL082 Opamp powered with +15 to GND )
The notes <= 36 gives +15V in the output of the opamp.
The note 37 gives +3.43V
The note 38 gives +1.7V
.
.
.then it increments as expected until note 108 which gives +7.52 V
Also to add I have +1.5V DC offset on the both outputs of the opamp.
(This, i can live with but i would love it not to happen. )
I would be very happy if you help me on this, thank you.
Comment: Find out what voltages are output by the DAC, and what voltages the opamp can handle.
Answer: I changed the opamp to LM358 and all problems solved it works perfectly!
If you have enough motivation and time please explain me why, but i will research and learn anyway.


How to pre-populate a field with the current users name?

Question: I want to pre-populate a form field with the value from another cck field from a different content type. I have been looking into using the prepopulate module and pathauto to get the correct url, but I am not sure that these will work. I am new to drupal and kinda lost in the storm with this problem.
Answer: To answer the question posed in the title of this question, you could in a custom module do something along the lines of...
<code>function MYMODULE_form_alter(&$form, $form_state, $form_id) {
  global $user;

  if ($form_id=='NODETYPE_node_form') {
     $form['field_FIELD'][0]['#default_value']['value']=$user->name;
  }

  // any other form alters you need

}
</code>
where MYMODULE is the name of your custom module, NODETYPE is the content type in question and FIELD is the field name in question without the field_ prefix.  Now, whenever you are editing or creating a content type of NODETYPE, the FIELD in question will have a prefilled default value of the current user's name.
Now, if this is a different form, you'll just need to adjust the $form_id== construct to point to that form, the field in that form, etc, but the rest of the logic should be the same.
Answer: I'm not sure how it would apply to your situation, and I'm sorry I don't really have time to check it out completely at the moment, but you could try using Entity Reference and Entity Reference Prepopulate. By using Entity Reference, the new content type will be related back to the user in a way that can be utilized by views and many other modules. I just realized, though, that it looks like you tagged this as Drupal 6, so this solution may not work for you if you cannot move to Drupal 7.
Comment: Thanks but yes I am using d6. I am sure it would be easier in d7 but currently thats not an option.


What are the differences between most Christian Bibles and Jehovah's Witnesses Bible?

Question: Are most Christian bibles and Jehovah's Witnesses Bible the same ? If not what are some important differences in them?
Comment: Possible duplicate of [Do Jehovah's Witnesses have their own version of the Bible?](https://christianity.stackexchange.com/questions/9295/do-jehovahs-witnesses-have-their-own-version-of-the-bible)
Comment: Welcome to Christianity Stack Exchange. When you have a moment, please take our [tour] and visit our [help].
Comment: There are similarities but this question asks specifically for the differences between the NWT and other translations.  I don't think this question is a duplicate of the one asked in August 2012.
Comment: @Lesley The answers to the other question only discuss the differences as well.
Comment: That's as maybe, but this question might elicit more responses and further insights. Perhaps we should wait and see?  I think the answer given by TRiG to the 2012 question provides excellent information. However, it's worth noting that the 2012 question is in error when it suggests that Jehovah's Witnesses don't accept other Bible translations. Up until 1961 (when the complete NWT was published) the Witnesses used the KJV.
Answer: The main difference between the New World Translation (NWT) and other Bibles is that the NWT has attempted to eliminate almost all references to the divinity of Jesus in the New Testament.  Another obvious difference is the introduction of the name 'Jehovah' into the New Testament.  This is also an attempt to deny that Jesus is God.
The King James Version text is based on the 'Textus Receptus' which is not used by the New World Translation, the New International Version, the New Living Translation or the English Standard Version.  The NWT Christian Greek Scriptures (New Testament) is mainly taken from the Westcott and Hort translation, but has been altered and changed to support the views of Jehovah's Witnesses that the pre-mortal Jesus was created by Jehovah and that Jesus is not part of the One Being of God.
It is true that Jehovah's Witnesses do not believe in the Trinity and they do not believe that Jesus is God.  See Section IV, V, and VI in the following article by Dr. Bruce M. Metzger, who was professor of New Testament at Princeton University.  The article also looks into the history and background of the New World Translation:   http://www.bible-researcher.com/metzger.jw.html
Here is a partial quote from an article that examines the background to the translators and the editing of the New World Translation and provides examples of the NWT anti-Trinitarian bias:

"New Testament, 1950. Frederick W. Franz, ed., New World Translation of the Christian Greek Scriptures Rendered from the Original Language by the New World Translation Committee. Brooklyn: Watchtower Bible and Tract Society, 1950.
Bible, 1961. Frederick W. Franz, ed., The New World Translation of the Holy Scriptures, rendered from the Original Languages by the New World Bible Translation Committee. Revised A.D. 1961. Brooklyn: Watchtower Bible and Tract Society of New York, 1961. The Old Testament was originally published in parts from 1953 to 1960. The whole was revised for the one-volume edition in 1961, and subsequently revised in 1970 and 1984.
The publisher of this version has never made public the names of the translators. But former members of the Governing Body of the Jehovah's Witnesses organization have identified the members of the committee as Nathan H. Knorr (President of the organization), Frederick W. Franz (Vice-President), George D. Gangas, and Albert D. Schroeder. According to Raymond V. Franz, the "principal translator of the Society's New World Translation" was Frederick W. Franz. (1) According to M. James Penton, "to all intents and purposes the New World Translation is the work of one man, Frederick Franz." (2) Franz afterwards became the President of the organization, from 1977 to 1992, and was responsible for the revisions.
The Forward to the first edition of the New Testament (1950) explained the need for the version, and also indicated the reason for its name: "It befits the significant time of transition from the old world to the righteous new world that translations of the Scriptures today should as far as possible eliminate the misleading influence of religious traditions which have their roots in paganism." (p.7, emphasis added.)
The New Testament adheres to the text of Westcott & Hort. It is a fairly literal translation, for the most part, but it does have some peculiar non-literal renderings. These are the result of the committee's efforts to conform the version to the doctrines of the Jehovah's Witnesses. "Jehovah" is given as a translation for kurios (Lord) in the New Testament whenever the Father is meant, but not when it refers to Christ, the Son. "Torture stake" is put instead of "cross" because the Jehovah's Witnesses believe that the cross is an idolatrous symbol introduced by the Roman Catholic Church. And because this sect teaches that Jesus Christ was merely an angel, the version shows an anti-trinitarian bias in several places."

Examples of Anti-Trinitarian bias then follow.   http://www.bible-researcher.com/new-world.html
Here is a short extract from the article 'The New World Translation - What the Scholars Really Said':

"The Watchtower and Jehovah's Witness apologists have often cited scholars in support of the New World Translation in general, and particularly its rendering of John 1:1c ("and the Word was a god").  Scholarly citation is a form of an "argument from authority."  Such an argument cannot establish the truth or falsity of a given assertion; it can merely lend credence or cast doubt.  Sound arguments from authority will consist of an accurate quotation from the scholar in question, which entails insuring that the context of the authority's statements are consistent with the argument being presented, and that contrary statements in the same passage are not removed with creative use of ellipses ("...").  Further, the scholar must be a recognized authority in a field that pertains directly to the assertion being made.
When Jehovah's Witnesses produce scholars that support the NWT, we must first establish that the scholar is, indeed, a recognized expert in the field of Biblical Languages, and that he or she has been quoted accurately.  When given careful consideration, many of the scholars used by Jehovah's Witnesses do not actually constitute a sound argument from authority.  I'm not suggesting that no scholars may be found in support of the NWT or its translation of John 1:1, but these are in the minority and often are not as qualified in their field as the scores of scholars who advocate the traditional translation."

The chart that follows examines how some scholars have been used in defense of the NWT and whether they actually support the Watchtower translation as claimed: http://www.forananswer.org/Top_JW/Scholars%20and%20NWT.htm
Readers are at liberty to study the articles referenced and to draw their own conclusions.
Comment: Jehovah's Witnesses would point out that references to Jesus' divinity were not in the original writings but were added to bolster trinitarian dogma.and that the name Jehovah was restored to its proper place in scripture not added.
Comment: The NWT also alters numerous Old Testament verses to better serve their purposes, along the same lines (especially as regards antitrinitarianism and anticatholicism)
Comment: @thedarkwanderer  alters Old Testament verses as written in which original earliest manuscripts? Or are you referring to altering from other translations  that are preferred by trinitarian and catholic scholars?
Comment: @Kris comments are not for discussion. My comment is a suggestion to the answerer that pointing out the alterations the Jehovah's Witnesses have made to the old testament in addition to the answer which currently focuses on the news testament may be a valuable addition.  I don't think citations refuting the Jehovah's Witnesses position as to their translations of the old testament would be useful in conveying my intent to the intended audience. I trust the answerer as they have shown themselves capable with the New Testament to do a similar job with the Old Testament.
Comment: @thedarkwanderer feel free to offer an answer that supplements this one with your examples of how NWT altered Hebrew Scriptures.
Comment: @Kris I'm not sure that's a good idea.  It seems to me to be of the 'suggest an edit via comments' level of additional content, as per [this](https://rpg.meta.stackexchange.com/questions/3326/should-i-be-requesting-people-answer-the-question-independently#3328).  That's for a different site in the network, though, so maybe this site's quality standards are lower or different. Are 'and here's a bit more' answers encouraged on Christianity.SE? I'll start a meta.
Comment: Let us [continue this discussion in chat](https://chat.stackexchange.com/rooms/80936/discussion-between-the-dark-wanderer-and-kris).
Comment: The divinity of Jesus is very much highlighted in the NWT to thr right degree as Jesus said : John 14:28 "the Father is greater than I am." with no time or space factor mentioned!
Answer: One major difference between the NWT and other bible translations is that the Watchtower Bible and Tract Society make it available, in print, at no cost to all in over 160 languages.  They take seriously Jesus command...you received free, give free.  Because monetary profit does not come into play,  the mainstream religious stamp of approval is not necessary to continue production.  If a translation gets a thumbs down from from the clergy of the major denominations, it won't sell.  Period.  Decide for yourselves if this might effect translators decisions when a difficult verse effecting doctrine can be translated in more than one way (especially after pouring decades of hard work into a translation) OR which translations are chosen for mass production by publishers.
https://www.newyorker.com/magazine/2006/12/18/the-good-book-business
Another distinctive feature of NWT is the fact that when a verse or word can be translated in more than one way that could effect the understanding, there is a note directing you to the appendix, which explains the possible options, sometimes with photos of original scrolls, why the translators have chosen to translate in such a way, and lists other translations that have also translated the verse in such a way.  I have never come across a bible that explains so thoroughly the translators viewpoint, with proofs so easily understood.
The online version goes further,  allowing the reader to compare each bible verse with other translations (those that are in the public domaine).  Also, if an individual wishes to do further research on a particular verse, the online watchtower library will take you there, often presenting the view of translators that understand the verse differently.  Jehovah's witnesses have no problem changing their beliefs if it's in harmony with the scriptures, (something they are often criticized for).  Popular or not, If it's in the NWT there's sound basis.
This being said, the NWT is pretty much the same as other translations.  The scriptures that raise controversy are comparatively few and mostly raise the ire of those who profess the trinity doctrine. You can see how passionate this discussion is by jumping over to bible hermeneutics...
https://hermeneutics.stackexchange.com/questions/1161/in-john-11c-should-the-greek-word-θεὸς-be-translated-into-english-as-a-god-o/1162
The restoration of Gods name in the NWT is somewhat controversial, but is certainly well founded in the Hebrew Scriptures and not without precedent in the Greek scriptures.
https://wol.jw.org/en/wol/d/r1/lp-e/2017128#h=12:294-13:190
https://www.jewishvirtuallibrary.org/great-bibles-judaic-treasures
https://wol.jw.org/en/wol/d/r1/lp-e/1001061205#h=12:0-12:761
But every translation brings something unique and valuable to the table. Jehovah's witnesses have deep respect for all translations and have no issue with using other translations in their bible education work.  Jehovah's witnesses also have a free bible museum open to the public in Warwick, N.Y., focused on Gods Holy name in scripture throughout the centuries. I've been there. It's amazing and awe inspiring.
A bible exhibit that glorifies gods name:
https://tv.jw.org/#en/mediaitems/VODBibleTranslations/docid-502016501_1_VIDEO
Below is a video about brave translators through the centuries such as William Tyndale and Michael Servetus:
https://tv.jw.org/#en/mediaitems/VODBibleTranslations/docid-502017151_1_VIDEO
Dhttps://www.jw.org/en/
Comment: It is disingenuous to assert that the differences are insignificant.
Comment: Small correction: the other Bibles found on jw.org are ones which the Watchtower Bible and Tract Society have received printing rights for. They aren't all in the public domain.
Comment: @DJClayworth I didn't mean to imply it was an insignificant difference that Gods Holy Name has been removed from many bibles. But throughout the scriptures there are many references where God makes clear he wants people to use his name, which clarifies whether it should have been removed in the 1st place.  Likewise, a person doesn't need to get involved in heated debates about which translation is best to understand Gods thinking on any matter when they discover the many other bible verses on any topic. This is why Jehovah's witnesses don't focus on which translation a person uses (2 Tim 3:16)
Answer: Many a prone to over react when talking about the NWT due to not knowing just what it says.
True they are verses that are bones of contention, but when put in a the context of the whole Bible they are in fact, very few in number.
What we preach is from on the King James Version of The Bible in the first instance as you can find the same teachings therein.
You would have to pick a verse or two to be examined openly.
Today many newer (some older) editions of The Bible now or do render various verses that are seen to be wrong in the NWT; the same way as the NWT doe or very close to the way it does, for example the following; John 1:1:-
VARIOUS OTHER RENDERINGS OF JOHN 1:1
Jesus Christ-The Wisdom and Word/Logos of God
The following is a list of variant translations of John 1:1:

Interlineary Word for Word English Translation-Emphatic Diaglott, "In a beginning was the Word, and the Word was with the God, and a god was the Word."
Edward Harwood, H KAINH DIAQHKH. The New Testament, collated with the most approved manuscripts; with select notes in English, critical and explanatory, and references to those authors who have best illustrated the sacred writings. To which are added, a Catalogue of the principal Editions of the Greek Testament; and a List of the most esteemed Commentators and critics. London, 1776, 2 vols; 2nd ed. 1784, 2 vols. 1768, "and was himself a divine person"
Newcome, 1808, "and the word was a god"
Crellius,as quoted in The New Testament in an Improved Version "the Word was God's"
La Bible du Centenaire, L'Evangile selon Jean, by Maurice Goguel,1928: "and the Word was a divine being."
John Samuel Thompson, The Montessoran; or The Gospel History According to the Four Evangelists, Baltimore; published by the translator, 1829, "the Logos was a god
Goodspeed's An American Translation, 1939, "the Word was divine
Revised Version-Improved and Corrected, "the word was a god."
Prof. Felix Just, S.J. - Loyola Marymount University, "and god[-ly/-like] was the Word."
The Four Gospels—A New Translation, by Professor Charles Cutler Torrey, Second Edition, 1947, "the Word was god
New English Bible, 1961, "what God was,the Word was"
Moffatt's The Bible, 1972, "the Logos was divine"
International English Bible-Extreme New Testament, 2001, "the Word was God*[ftn. or Deity, Divine, which is a better translation, because the Greek definite article is not present before this Greek word]
Reijnier Rooleeuw, M.D. -The New Testament of Our Lord Jesus Christ, translated from the Greek, 1694, "and the Word was a god"
Simple English Bible, "and the Message was Deity"
Hermann Heinfetter, A Literal Translation of the New Testament,1863, [A]s a god the Command was"
Abner Kneeland-The New Testament in Greek and English, 1822, "The Word was a God" Robert Young, LL.D. (Concise Commentary on the Holy Bible [Grand Rapids: Baker, n.d.], 54). 1885,  "[A]nd a God (i.e. a Divine Being) was the Word"
Belsham N.T. 1809 "the Word was a god"
Leicester Ambrose, The Final Theology, Volume 1, New York, New York; M.B. Sawyer and Company, 1879, "And the logos was a god"
Charles A.L. Totten, The Gospel of History, 1900, "the Word was Deistic [=The Word was Godly]
J.N. Jannaris, Zeitschrift fur die Newtestameutlich Wissencraft, (German periodical) 1901, [A]nd was a god"
International Bible Translators N.T. 1981 "In the beginning there was the Message. The Message was with God. The Message was deity."
Samuel Clarke, M.A., D.D., rector of St. James, Westminster, A Paraphrase on the Gospel of John, London "[A] Divine Person."
Joseph Priestley, LL.D., F.R.S.  (in A Familiar Illustration of Certain Passages of Scripture Relating to The Power of Man to do the Will of God, Original Sin, Election and Reprobation, The Divinity of Christ; And, Atonement for Sin by the Death of Christ [Philadelphia: Thomas Dobson, 1794], 37). "a God"
Lant Carpenter, LL.D (in Unitarianism in the Gospels [London: C. Stower, 1809], 156). "a God"
Andrews Norton, D.D. (in A Statement of Reasons For Not Believing the Doctrines of Trinitarians [Cambridge: Brown, Shattuck, and Company, 1833], 74). "a god"
Paul Wernle, Professor Extraordinary of Modern Church History at the University of Basil (in The Beginnings of Christianity, vol. 1, The Rise of Religion [1903], 16).  "a God" "At the beginning of Creation, there dwelt with God a mighty spirit, the Marshal, who produced all things in their order."
21st Century NT Free "and the [Marshal] [Word] was a god." 21st Century Literal
George William Horner, The Coptic Version of the New Testament, 1911, [A]nd (a) God was the word"
Ernest Findlay Scott, The Literature of the New Testament, New York, Columbia University Press, 1932, "[A]nd the Word was of divine nature"
James L. Tomanec, The New Testament of our Lord and Savior Jesus Anointed, 1958, [T]he Word was a God"
Philip Harner, JBL, Vol. 92, 1974, "The Word had the same nature as God"
Maximilian Zerwich S.J./Mary Grosvenor, 1974, "The Word was divine."
Siegfried Schulz, Das Evangelium nach Johannes, 1975, "And a god (or, of a divine kind) was the Word"
Translator's NT, 1973, "The Word was with God and shared his nature ...with footnote, "There is a distinction in the Greek here between 'with God' and 'God.' In the forst instance, the article is used and this makes the reference specific. In the second instance there is not article, and it is difficult to believe that the omission is not significant. In effect it gives an adjectival quality to the second use of Theos (God) so that the phrae means 'The Word was divine'."
William Barclay's The New Testament, 1976, "the nature of the Word was the same as the nature of God"
Johannes Schneider, Das Evangelium nach Johannes, 1978, "and godlike sort was the Logos
Schonfield's The Original New Testament, 1985, "the Word was divine
Revised English Bible, 1989, "what God was, the Word was
Scholar's Version-The Five Gospels, 1993, "The Divine word and wisdom was there with God, and it was what God was
J. Madsen, New Testament A Rendering , 1994, "the Word was a divine Being"
Jurgen Becker, Das Evangelium nach Johannes, 1979, "a God/god was the Logos/logos"
Curt Stage, The New Testament, 1907, "The Word/word was itself a divine Being/being."
Bohmer, 1910, "It was strongly linked to God, yes itself divine Being/being"
Das Neue Testament, by Ludwig Thimme, 1919, "God of Kind/kind was the Word/word"
Baumgarten et al, 1920, "God (of Kind/kind) was the Logos/logos"
Holzmann, 1926, "ein Gott war der Gedanke" [a God/god was the Thought/thought]
Friedriche Rittelmeyer, 1938, "itself a God/god was the Word/word"
Lyder Brun (Norw. professor of NT theology), 1945, "the Word was of divine kind"
Fredrich Pfaefflin, The New Testament, 1949, "was of divine Kind/kind"
Albrecht, 1957, "godlike Being/being had the Word/word"
Smit, 1960, "the word of the world was a divine being"
Menge, 1961, "God(=godlike Being/being) was the Word/word"
Haenchen, 1980, "God (of Kind/kind) was the Logos/logos" [as mentioned in William Loader's The Christology of the Fourth Gospel, p. 155 cf. p.260]
Die Bibel in heutigem Deutsch, 1982, "He was with God and in all like God"
Haenchen (tr. By R. Funk), 1984, "divine (of the category divinity)was the Logos"
Johannes Schulz, 1987, "a God/god (or: God/god of Kind/kind) was the Word/word." [As mentioned in William Loader's The Christology of the Fourth Gospel, p. 155 cf. p.260]
William Temple, Archbishop of York, Readings in St. John's Gospel, London, Macmillan & Co.,1933, "And the Word was divine."
John Crellius, Latin form of German, The 2 Books of John Crellius Fancus, Touching One God the Father, 1631, "The Word of Speech was a God"
Greek Orthodox /Arabic Calendar, incorporating portions of the 4 Gospels, Greek Orthodox Patriarchy or Beirut, May, 1983, "the word was with Allah[God] and the word was a god"
Ervin Edward Stringfellow (Prof. of NT Language and Literature/Drake University, 1943, "And the Word was Divine"
Robert Harvey, D.D., Professor of New Testament Language and Literature, Westminster College, Cambridge, in The Historic Jesus in the New Testament,  London, Student Movement Christian Press1931  "and the Logos was divine (a divine being)"
Jesuit John L. McKenzie, 1965, wrote in his Dictionary of the Bible: "Jn 1:1 should rigorously be translated . . . 'the word was a divine being.'

Many are inclined to say the only The NWT renders John 1:1 "a god," the above shows this very much so not to be the real case!!  Also we refuse to substitute God's personal "name" "Jehovah" for phrase "the LORD" which is an illegal change:-

NWT Deuteronomy 4:2  "YOU MUST NOT add to the word that I am commanding you, neither must you take away from it, so as to keep the commandments of Jehovah (Heb. YHWH) your God that I am commanding you.
Comment: "Also we refuse to substitute God's personal "name" "Jehovah" for phrase "the LORD"" is that you claiming that the New Testament has been corrupted, then? And if corrupted, how do you choose when kurios was originally yhvh or adoni?
Comment: Also, why do you cite "what God was,the Word was" and "the nature of the Word was the same as the nature of God" among translations supposed to support the idea that θεος ην ο λογος means 'the Word was a god?' The above contradict this and say He has the same nature as God. Only one Being as the eternal divine nature, or do JW reject that?
Comment: @Sola Geatia  Yep same nature; but not the same person!
Comment: But God's nature is the eternal and so infinite God of all creation. It's not something less.

What are the differences between most Christian Bibles and Jehovah’s Witnesses Bible?


Jelly bean phone won't let me get to the APN setting

Question: I just bought a android Jelly Bean phone and I use straight talk, I still have a active Sim card, but the phone won't let me get to set the Apn. When I press on settings for the Apn I doesn't go there. Is there another way to get there to set the APN? Please help. Thank you
Comment: Do you get to the list of APNs? Maybe a screenshot indicating what you are trying might help.
Answer: I agree that it was a little misleading / not-leading to anywhere. With the following steps Jelly Bean (v4.1.2) let me go set a new APN with Samsung Galaxy S 4G Relay:

Settings --> may need to press More settings --> Mobile Networks --> Access Point Names
Press the "button that leads to setting page" (sorry I don't know how to call this button. On my device it's one of the three main hardware buttons where the others are "Back", "Home"). There you'll see New APN and Reset Default.


Data set for document topic discovery

Question: I have a bunch of documents and would like to to assign one (or more) topics to each document. The topics can be quite wide ranging from political topics to sports, etc. I think the best way is to deal with this problem as a classification problem however my main issue is a good and accurate training data set. The data set should be quite generic and covers diverse range of topics. I'd like to know whether there is any training data set out there for this purpose? There might be some data sets mostly for research purposes but I need an accurate one (even if it deosn't come for free).
Comment: try wikipedia: http://dumps.wikimedia.org/enwiki/latest/
Answer: You suggest that the best way is to treat the problem as a classification problem. However, in many cases topic discovery or topic modelling is treated as an unsupervised learning problem, meaning that you do not need to have the correct label for each document beforehand. A well known probabilistic model for this purpose is Latent Dirichlet Allocation. In LDA, each document is represented as a bag of words. Words in each document are assumed to be generated from a number of topics. Topics (there can be more than one) in each documents are automatically discovered along with relevant weights (probabilities). Useful resources can be found on David Blei's page.
Comment: I am familiar with LDA. It is useful when the documents are talking about the same topic and we would like to know what that topic(s) is. However consider a case in which you got a million document and each document is talking about a unique topic. There is no way to use LDA in this scenario. In this scenario we should first do a clustering to find similar documents and then do a LDA for each cluster which may not be possible when data set is big!
Comment: You should update your question to reflect this. I did not realize you are considering a big data scenario.
Comment: @H.Z. You should use then online versions of the LDA algorithm like the one implemented in Vowpal Wabbit. It will happily crunch terabyte scale dataset even on a modest laptop.
Comment: @H.Z. I'm a bit confused... do you mean that each document has a unique topic (in your example, there are a million distinct topics) or that there a large number of topics (maybe 100 or 1,000) and that each document has some mixture of the topics? In the latter case, LDA will work (albeit, slowly unless you use the online version as xeon suggested).
Answer: Following your latest comment with regards to "each document is talking about a unique topic", I would suggest you to try the mixture-of-unigrams topic model (i.e. one topic per document). The model details with Gibbs sampling-based inference are presented in:
Jianhua Yin and Jianyong Wang. 2014. A Dirichlet Multinomial Mixture Model-based Approach for Short Text Clustering. In Proceedings of the 20th ACM SIGKDD International Conference on Knowledge Discovery and Data Mining, pages 233–242.
http://dbgroup.cs.tsinghua.edu.cn/wangjy/papers/KDD14-GSDMM.pdf
You can also find my Java implementation for this model at http://jldadmm.sourceforge.net/
Answer: Mallet comes with a small sample corpus (some English and German texts from Wikipedia) to get the gist of it.
For learning a new tool I suggest that you first use a dataset that you already understand well.

Data set for document topic discovery


How to manage a growing MySQL slow_log table?

Question: I see MySQL supports storing slow_log as a table (internally using mysql/slow_log.CSV file), and this appears convenient, but is it a feature I should use in production? I found online articles on the importance of temporarily disabling slow query logging while rotating the file log, but what's the best practice for managing slow_log.CSV? eg. copy and truncate table or rotate the slow_log.CSV just like db-slow.log?
Answer: First of all, I discourage you from using the slow log with TABLE output, in production. The reason is that writes are locking, which limits the concurrency of your workload.
Moreover, CSV stored engine does not support indexes. Any non-trivial query will be very slow, so I don't see any advantages in doing this. Of course you could use MyISAM and add indexes, but then writes will become more expensive.
That said, the correct way to "rotate" the table is copying it and than truncate it. You will probably lose some queries every time: the ones ran after the copy but before the TRUNCATE TABLE statement.
Answer: The Slow Query Log can be handled for CSV and MyISAM
CSV (RDS)
For those who used MySQL RDS and enable the slow log, Amazon will use CSV only. The RDS environment can auto-rotate at a specific time every night. If you using MySQL RDS and wish to use slow logs, let RDS do its thing.
CSV (Non-RDS)
If you wish to manage you own slow log rotations (CSV or MyISAM)
Run one of these at 11:59 PM every night
Log Rotate One Day
SET GLOBAL slow_query_log = 'OFF';
SET sql_log_bin = 0;
USE mysql
DROP TABLE IF EXISTS slow_log_new;
DROP TABLE IF EXISTS slow_log_old;
CREATE TABLE slow_log_old LIKE slow_log;
ALTER TABLE slow_log RENAME slow_log_old;
ALTER TABLE slow_log_new RENAME slow_log;
SET GLOBAL slow_query_log = 'ON';
SET sql_log_bin = 1;

Log Rotate With Date in Log Name
SET GLOBAL slow_query_log = 'OFF';
SET sql_log_bin = 0;
USE mysql
SET @ymd = DATE_FORMAT(NOW(),'%Y%m%d');
DROP TABLE IF EXISTS slow_log_old;
ALTER TABLE slow_log RENAME slow_log_old;
CREATE TABLE slow_log LIKE slow_log_old;
SET @sql = CONCAT('ALTER TABLE slow_log_old RENAME slow_log_',@ymd);
PREPARE stmt FROM @sql; EXECUTE stmt; DEALLOCATE PREPARE stmt;
SET GLOBAL slow_query_log = 'ON';
SET sql_log_bin = 1;

MyISAM
See my old posts for MyISAM-based slow logs

Mar 30, 2012 : MySQL slow log configuration
Jan 08, 2012 : How to enable MySQL general log?

Final Thoughts
In a high-read, low write environment, doing writes to the slow would be faster to a CSV file that to MyISAM any other engine. Amazon uses it without hesitation. As far as doing queries against a CSV, it's just a full table scan every time
Comment: In the first example, I suggest doing an atomic `RENAME TABLE slow_log TO slow_log_old, slow_log_new TO slow_log;` instead of the two `ALTERs`.


External tools for Eve Online

Question: What tools do you suggest to use on the desktop (Windows) to help me with the game. I know there is an API that exposes a lot of information.
I was thinking that it would be nice to have a tool that would show me my expenses and sales on the market to be able to analyze it, maybe export to excel, etc.
Comment: I vote for community wiki because the up votes are purely based on preference and opinion.
Comment: I second that vote. External EVE tools change rapidly over time making this question and the answers out of date very quickly.
Answer: The canonical example would have to be EVEmon. Not only does it let you monitor your skill queue from outside the game and notify you when training finishes, but it also has an excellent ship and item browser that lets you quickly look up the statistics on anything you're interested in as well as find out whether you have the necessary skills to use it.
Comment: It now also monitors Evemail.
Answer: Eve Fitting Tool is useful for planning your future ship builds. You can export it to Evemon to automatically generate an optimized learning plan as well.
An excellent resource for finding 3rd party tools is the Third Party Tools category on EVElopedia
Comment: Now that CCP got rid of the learning skills, optimization of learning plans is no longer necessary. But Evemon will still generate a learning plan for your desired ship and fitting.
Answer: I highly recommend Eve Commander. It's not an application, but rather a webapp that manages all kinds of information for you.
Great interface, lots of useful stuff, very responsive developer.
It's not free, but paid for with in-game money. The prices are very reasonable, it was easily affordable and worth the money even for me as an Eve newbie.
Comment: +1 - the only real thing it's missing is skill planning - other than that it's wonderful (I have it bookmarked on my phone as it's better than any app I've tried).
Comment: It's no EVEMon, that's for sure, but doesn't it at least show your list of skills and your learning queue? No planning features, though.
Comment: Its actually been shut down now.
Comment: @GWLlosa Indeed, how sad. :(
Answer: I use these: ( link with URLs http://eve.nako.us/tools/external-tools-for-eve-onine )
EVEMon - EVEMon is a lightweight, easy-to-use standalone Windows application designed to assist you in keeping track of your EVE Online character progression.
EveHQ
EveHQ is an extensible character application for use in conjunction with Eve-Online.Initially starting out as a character monitor and skill planner, EveHQ adopted a plug-in system where additional modules could be created independently of the main application which would extend the functionality of the program as a whole.
EFT - EVE Fitting Tool
Wormhole Thingie - Shows some useful info on wormholes and w-space systems.
EVE Asset Manager
MyPOS
Eve-Metrics Market upoader
Eve-central Upload Utility
2D Maps, PDF
DOTLAN Eve Maps
EVEMap is an out of game map of the EVE universe.
Comment: Summary posts don't work well on StackExchange, because it breaks the ranking and ordering by upvotes. Just FYI why I'm not upvoting that. Create a separate answer for e.g. the EVEMap, which is quite awesome (if it's the PDF that I remember).
Comment: @Cort Au contraire. This is what we prefer on this site.
Comment: @ArdaXi Yeah, my comment was mostly pre the strategy change regarding summarising posts on SE. :)
Answer: I am using http://eve.grismar.net/explorer/index.php quite often to find stuff in EVE. Most of the time I am looking for a new agent for a certain corp. Most other tools don't let me specify as much conditions to limit what is show to me.
I can i.e. say "I want a agent for Federation Navy that provides lvl 4 missions, mostly kill missions, resides in 0.5+ systems, and is available with my standings."
Answer: I would recommend taking a look at EVEHQ, it covers most of the information exposed by the API.
Comment: Battleclininc are discontinuing EVEHQ last time I looked

External tools for Eve Online


Is blending of colour lights a linear system?

Question: Can we consider recombination process of different light colors a linear system/phenomenon? Like, when you shed two different light sources for example, a blue light and a yellow light on a surface or recombine them through a prism , the resultant light would be green which has a different frequency that the inputs. Producing a new frequency component other than what were in input (Is this assumption correct?) This is contrary to definition of linear systems I assume. So is this process linear, if not, how is it non-linear, I mean the whats the physics?
I've wondered this question from time to time and I know I probably have some wrong assumption some where. I would appreciate if someone clarify things for me or point out my wrong supposition(s).
Comment: Eventhough a qualitative discussion is quite possible on the basis of a physical **definition** of the system you mention, formally it is necessary to define the **mathematical** representation of the system, in order to talk **precisely** about the **linearity** (or any other) property of it.
Comment: I think, I have had a misassumption on blending of colors. The fact is, they do not blend when we see them. Actually they feel to be mixed because of our receptors in our cornea. So nothing non linear or linear happens, simply it is an perception and illusion.
Answer: Your mistake is that you are describing subtractive color mixing, not applicable in this scenario.
If you shed two lights onto a diffuse surface that does not absorb any light, and collect all the light diffusely reflected, the sum will be an additive mixture of the two. Incoherent (non-laser) light can be thought of as noise that has some electromagnetic spectral power distribution. From the signal processing point of view, long-time average power spectra of independent noise signals mix additively when they are summed
Comment: Thanks for responding, **From the signal processing point of view, long-time average power spectra of independent noise signals mix additively when they are summed**, so you mean light blending (either subtractive or additive) is a random process?
Comment: @MimSaad Sorry I have no time to answer now, but here are some links to read: https://en.wikipedia.org/wiki/Electromagnetic_field https://en.wikipedia.org/wiki/Diffuse_reflection and also note that subtractive mixing is much harder to model so don't go into it if you can avoid it. If you really must understand subtractive color mixing there is the Kubelka-Munk theory.


Why are fine metal filters made of meshes?

Question: Given that we have mechanisms of performing photolithography at 10nm, why are metal filters often meshes? Wouldn't it make a lot more sense to buy a single chunk of metal, and use the UV lasers to poke lots of N micron holes in it?
Comment: The mesh is a cheaper solution.
Answer: Photo-lithography is expensive and is generally more useful in etching away some surface layer than drilling holes. Generally the light source doesn't actually remove material but selectively cures a coating on the surface which masks off teh pattern to be etched.
Compared to weaving which was one of the first ever processes to be mechanised and automated this is an expensive and time-consuming process.
If you want very fine filters they are often made my sintering fine metal particles produced by vacuum deposition.
Answer: When using a laser to drill holes you are melting or sublimating the material, The liquefied/evaporated metal has to go somewhere before it solidifies again where you don't want it to and possible plugging the hole again.
Building the filter by only adding material makes sure there is nothing extra where you don't want it (the holes).
Making them out of meshes also means they can be (partially) disassembled and cleaned.
Answer: Using a mesh means that, not only are they cheap relatively, but they can be scaled easily to suit the task required, so a mesh for tea leaves or a mesh to allow concrete to be poured through etc etc.
Answer: There are MANY ways to make filters:
A metal mesh is one.  Works well from gravel down to fine sand.
In your coffee pot you use a paper filter.  Will take out sand, but will pass suspended clay.
Landscape fabric is often needle punched -- a 50 to 100 micro hole every 5 mm. As a filter it's not very efficient.  But it only has to let through a foot or  two of water a year.
Another not so common filter are a stack of rough disks.  The liquid passes btween the disks.  This has fairly low back pressure.
You can make filters out of spun plastic that is heat fused.  This is basically what tyvek housewrap is.
The waterproofing in Goretex garments is basically teflon that is stretched so that liquid water had too much surface tension to squeeze through the holes, but water vapour passes thorugh.  There is heavy magic in getting the right plastic cross linking and the right stretching.
One type of oil filter consisted of a frame that would hold a roll of toilet paper.  Oil pass through the roll lengthwise.


Adding an additional GPU for LTC mining

Question: I've just recently started litecoin mining on a kind of old AMD GPU.  My motherboard has space for 2 additional cards.  I'd like to drop in a new card specifically for litecoin mining, but...  I'm not sure if the two cards need to be identical.  Crossfire stuff is confusing me.  If I drop in a second card can it be top of the line and still have my old card do some work?
Answer: The cards don't need to be identical. Your mining software should identify each GPU and allow you to control/use each one separately.

Adding an additional GPU for LTC mining