ruby-gsl on windows - cygwin howto

I wanted to use gruff. But it seems that doesn't support complex math functions. So I decided to choose gnuplot and gsl which turned out pretty confusing, especially on cygwin. I googled all day to find out how to invoke gem command on cygwin(Yeah. I was fool.) Anyway here is what I've found. I hope this will help you too.

1. installing cygwin including gnuplot and gsl
(http://www2.warwick.ac.uk/fac/sci/moac/currentstudents/peter_cock/cygwin/part5/)

Default permissions

As mentioned in http://cygwin.com/ml/cygwin/2006-01/msg00257.html, the default permissions for a Cygwin installation are rwxrwxrwx. Even if you don't care about the security implications, Ruby does. You might get sick of seeing Ruby make complaints like:

warning: Insecure world writable dir /usr/local/bin, mode 040777

The directory and exact mode may differ, but you'll need to chmod o-w the directory in question. Here's the minimal set of changes I needed to make to keep Ruby quiet:

chmod o-w /usr/local/bin
chmod o-w /usr/local
chmod o-w /usr
chmod o-w /etc
chmod o-w /usr/sbin
chmod o-w /usr/bin
chmod o-w /usr/X11R6/bin
chmod o-w /usr/X11R6
chmod o-w /cygdrive/c

Of course, this still leaves every binary on your system world-writable. Strangely, Ruby's happy to run world-writable binaries, as long as the directory they're in isn't world-writable.

2. If your want to use gem properly on cygwin, you need to alias commands.
home/.bashrc contains a set of aliases

# Force the c:/ruby version to be found first
PATH=/cygdrive/c/ruby/bin:$PATH

alias autotest='ruby /ruby/bin/autotest'
alias cap='ruby /ruby/bin/cap'
alias gem='ruby /ruby/bin/gem'
alias rake='ruby /ruby/bin/rake'
alias rcov='ruby /ruby/bin/rcov'
alias ruby='/cygdrive/c/ruby/bin/ruby'
alias specrb='ruby /ruby/bin/specrb'

3. installing ruby-gsl
http://ruby-gsl.sourceforge.net/
- download ruby-gsl
- ./configure
- make
- make install

4. Happy coding.

If you have some troubles such as "permission denied" while installing plotutils,
check this article =>
http://ptolemy.eecs.berkeley.edu/~cxh/ptpub/nt/ptntinstall.html

I've installed gem on cygwin.

unset RUBYOPT
chmod -R a+w /usr/lib/ruby/site_ruby/1.8/rubygems
ruby setup.rb
(no more permission denied Errorno:EACCES)

And I followed this article.
http://www.gfd-dennou.org/arch/ruby/