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What is NODE_ENV and how to use it in Express?
...NV is an environment variable made popular by the express web server framework. When a node application is run, it can check the value of the environment variable and do different things based on the value. NODE_ENV specifically is used (by convention) to state whether a particular environment is a ...
Bash Script : what does #!/bin/bash mean? [duplicate]
...rom Wikipedia)
#!/bin/sh — Execute the file using sh, the Bourne shell, or a compatible shell
#!/bin/csh — Execute the file using csh, the C shell, or a compatible shell
#!/usr/bin/perl -T — Execute using Perl with the option for taint checks
#!/usr/bin/php — Execute the file using the PHP ...
What is the relation between BLAS, LAPACK and ATLAS
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BLAS is a collection of low-level matrix and vector arithmetic operations (“multiply a vector by a scalar”, “multiply two matrices and add to a third matrix”, etc ...).
LAPACK is a collection of higher-level linear algebra operations. Things like matrix factorizat...
What's the difference between an id and a class?
...ic element and class when you have a number of things that are all alike. For instance, common id elements are things like header, footer, sidebar. Common class elements are things like highlight or external-link.
It's a good idea to read up on the cascade and understand the precedence assigned to ...
String output: format or concat in C#?
Let's say that you want to output or concat strings. Which of the following styles do you prefer?
31 Answers
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Using i and j as variables in Matlab
... i and j are both functions denoting the imaginary unit:
http://www.mathworks.co.uk/help/matlab/ref/i.html
http://www.mathworks.co.uk/help/matlab/ref/j.html
So a variable called i or j will override them, potentially silently breaking code that does complex maths.
Possible solutions include usi...
How does StartCoroutine / yield return pattern really work in Unity?
I understand the principle of coroutines. I know how to get the standard StartCoroutine / yield return pattern to work in C# in Unity, e.g. invoke a method returning IEnumerator via StartCoroutine and in that method do something, do yield return new WaitForSeconds(1); to wait a second, th...
Recursion or Iteration?
Is there a performance hit if we use a loop instead of recursion or vice versa in algorithms where both can serve the same purpose? Eg: Check if the given string is a palindrome.
I have seen many programmers using recursion as a means to show off when a simple iteration algorithm can fit the bill.
D...
How to write an async method with out parameter?
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You can't have async methods with ref or out parameters.
Lucian Wischik explains why this is not possible on this MSDN thread: http://social.msdn.microsoft.com/Forums/en-US/d2f48a52-e35a-4948-844d-828a1a6deb74/why-async-methods-cannot-have-ref-or-out-parameters
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Limit ggplot2 axes without removing data (outside limits): zoom
...cify axis limits in ggplot the outlying points are removed. This is fine for points, but you might want to plot lines that intersect with the specified range, but ggplot's range or xlim/ylim methods removes these. Is there another way to specify the plot axis range without removing outlying da...