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Why are these numbers not equal?
...cially true because some values which are simple, finite decimals (such as 0.1 and 0.05) are not represented exactly in the computer and so the results of arithmetic on them may not give a result that is identical to a direct representation of the "known" answer.
This is a well known limitation of ...
How to make an OpenGL rendering context with transparent background?
...ndows XP (32-bits) and Windows 8.1 (32-bits).
Enjoy!
#define _WIN32_WINNT 0x0500
#include <windows.h>
#include <windowsx.h>
#include <GL/gl.h>
#include <GL/glu.h>
#pragma comment (lib, "opengl32.lib")
#pragma comment (lib, "glu32.lib")
#include <assert.h>
#include &...
How to randomize (or permute) a dataframe rowwise and columnwise?
...
Given the R data.frame:
> df1
a b c
1 1 1 0
2 1 0 0
3 0 1 0
4 0 0 0
Shuffle row-wise:
> df2 <- df1[sample(nrow(df1)),]
> df2
a b c
3 0 1 0
4 0 0 0
2 1 0 0
1 1 1 0
By default sample() randomly reorders the elements passed as the first argument. This m...
How to profile a bash shell script slow startup?
... you'd like to begin a trace in any Bash script):
PS4='+ $(date "+%s.%N")\011 '
exec 3>&2 2>/tmp/bashstart.$$.log
set -x
add
set +x
exec 2>&3 3>&-
at the end of ~/.bashrc (or at the end of the section of any Bash script you'd like tracing to stop). The \011 is an octal ...
Get operating system info
...
202
The code below could explain in its own right, how http://thismachine.info/ is able to show whi...
PHP Regex to check date is in YYYY-MM-DD format
...
Try this.
$date="2012-09-12";
if (preg_match("/^[0-9]{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$/",$date)) {
return true;
} else {
return false;
}
share
...
What's the difference between tilde(~) and caret(^) in package.json?
...
4053
See the NPM docs and semver docs:
~version “Approximately equivalent to version”, will up...
Dynamically update values of a chartjs chart
...
101
Update: Looks like chartjs has been updated (see comment below). There are some examples up th...
Bomb dropping algorithm
...the only way to reduce the hollow rectangle of squares on the
perimeter to 0 is to bomb either the perimeter or to bomb the hollow rectangle of
squares just inside the perimeter. I'll call the perimeter layer 1, and the rectangle inside it layer 2.
An important insight is that there is no point b...