Newbie help using GSL and the "--with-gsl-prefix" command

[yazooney]

Hi,

Currently trying to ./configure;make;make install a program called gmsh. I installed gsl through cygwin. However, everytime i try and ./configure the program gmsh, i get:

******************************************************************
This is the free version of Gmsh and configure could not find
the GNU Scientific Library (GSL) on your system:
- if it is installed in a non-standard location, please run
configure again with the --with-gsl-prefix option

Ok. As a complete newbie can someone point me in the right direction which does not involve me using trial and error for hours. Heres what i done so far

cygwin is installed in directory c:\cygwin
The gsl folder where i ran the ./configure; make; make install is installed in directory c:\randomdirectory.

When i type into cygwin "whereis gsl" i get:
gsl: usr/include/gsl /usr/share/man/man3/gsl.3.gz

From what I have worked out I have reckon i have to type something like:
./configure --with-gsl-prefix="PATH"

I tried path usr/include/gsl but it wont work. Anyone can help me?