No Disconnect

How SVG units work

nodisconnect — Wed, 04 Jan 2012 05:52:49 +0000

From the specification:

“1pt” equals “1.25px” (and therefore 1.25 user units)
“1pc” equals “15px” (and therefore 15 user units)
“1mm” would be “3.543307px” (3.543307 user units)
“1cm” equals “35.43307px” (and therefore 35.43307 user units)
“1in” equals “90px” (and therefore 90 user units)

Linux remove directory and all contents

nodisconnect — Mon, 02 Jan 2012 10:04:30 +0000

rm -rf NameOfTheDirectory

What to do with all the GTK+ library files in Win32

nodisconnect — Mon, 02 Jan 2012 06:29:20 +0000

Lots of files are helpfully provided here: http://www.gtk.org/download/win32.php

Not bad Win32 support for a GPL, but as is typical, they don’t tell you what to do with them.

What you do is open the zip files, and merge them with the folders in your MinGW directory. The best way I found to do that is to move the zip file to my mingw directory (in my case, C:\Qt\4.7.1\mingw), and then use Windows’ “Extract all…” feature, which will offer to merge the directories automatically.

One more wrinkle: the “Dev” versions are necessary to build code using the libraries; the “Run-time” versions are necessary to actually execute the program. Both need to be installed as described above.

The actual HTML Tidy documentation

nodisconnect — Wed, 28 Dec 2011 09:29:06 +0000

For whatever reason there are a ton of pages purporting to document HTML Tidy. This one seems to be the real one:

http://tidy.sourceforge.net/docs/tidy_man.html

Insert characters around characters in XeLaTeX (for RTL languages)

nodisconnect — Sat, 03 Dec 2011 10:36:31 +0000

In typesetting RTL documents in XeLaTeX, I have found that characters such as colons or parentheses don’t set properly—adjacent numbers disappear, etc. The code below makes TeX place empty hbox’s around each colon in a document. No further references to macros are necessary.

\def\colon{:}
\catcode`:=\active
\def:{\hbox{}\colon\hbox{}}

Get the variables/attributes/members of an object

nodisconnect — Fri, 15 Jul 2011 15:00:05 +0000

names(myObject);

xsltproc (XSL transformations)

nodisconnect — Mon, 20 Jun 2011 10:39:22 +0000

xsltproc is the best (most efficient) way I’ve found to do XSL transformations. Some of the DLL dependencies have to be from libraries downloaded at the xsltproc web site (or rather, the web site of the associated libraries).

xsltproc ocm.xsl newOcm.xml > result.txt

xsltproc --param which-page 1 -o output.svg xml2svg.xsl nasim.xml

xsltproc --param which-page "hello world" -o output.svg xml2svg.xsl nasim.xml

C++ object/pointer construction/deconstruction

nodisconnect — Wed, 02 Mar 2011 05:58:50 +0000

#include 

using namespace std;

class A
{
public:
 char label;
 A()
 {
 label = 'X';
 }
 A(char l)
 {
 label = l;
 cout << "Constructing " << label << endl;
 }
 ~A()
 {
 cout << "Deconstructing " << label << endl;
 }
};

int main()
{
 A a('a');
 A *b;
 A *c = new A('c');
 A *d = new A('d');
 delete d;

 return 0;
}

Output:

Constructing a
Constructing c
Constructing d
Deconstructing d
Deconstructing a

Getting coefficients and p-values from an R lm class

nodisconnect — Wed, 26 Jan 2011 05:04:59 +0000

dependent <- runif(100);
independent <- runif(100);
tmp<-lm(dependent ~ independent);
summary(tmp);
correlation <- tmp$coeff['independent'];
intercept <- tmp$coeff['(Intercept)'];
f <- summary(tmp)$fstatistic;
p_value <- 1-pf(f['value'], f['numdf'], f['dendf'])

Principal component analysis in Octave

nodisconnect — Tue, 25 Jan 2011 09:27:26 +0000

% create sample data
matrix = [1 2 3; 4 5 6; 7 8 9; 10 11 12];
matrix = matrix.^2;

matrix = center(matrix); % subtract column means
cv = cov(matrix); % calculate covariance
[v, lambda] = eig(cv); % compute eigenvectors and eigenvalues
[sorteigen, order] = sort(diag(lambda),'descend'); % sort the eigenvalues
v = v(:,order); % sort the eigenvectors the same way

data = [1 2 3; 4 5 6; 7 8 9; 10 11 12]; % a new dataset
means = mean(data); % calculate the column means
data = center(data); % subtract the means
transdata = v' * data'; % project into the new eigenspace
reconstituted = (v*transdata + repmat(means,size(data,1),1)')'; % project it back the other way, and add the means back