long double version of C's sqrt() function?

I'm wanting to write my own long double version of C's sqrt function. The sqrtl function already does this, but it's not part of ANSI C. So I'd like to be able to access the source code for sqrt or sqrtl to see how to write my own version and make my C program compatible with ANSI C. Does anyone know how I can look at this source code?

I would look at the GNU C++ libraries and search through this. Another avenue is to look through http://www.Koders.com . Google also have something similar, so you should be able to type in sqrtl and find anything relevant.