I'd like to know what algorithms are used for the C implementations of these functions (sqrt and pow (actually I'm only interested in pow to calculate nth roots, i.e. with exponents 1/n)). I tried to find the source files that I thought must be around somewhere on my Linux system but I couldn't find them, I only found math.h.

I know that Intel provides an assembly instruction fsqrt, so maybe C doesn't even have anything to do with the algorithm but just calls this function?