Torbjörn, > I am not proud of the mpn_sqrtrem1 code. It was made with some analysis > and lots of testing. The many undocumented magic constants are ugly. > Perhaps I should never have checked in this code.
ah ok. I have an alternate implementation which is almost as efficient, but although it passes make check with both GMP and MPFR, I have not yet proven it is correct :-( > Furthermore, for a real performance win one would need to rewrite > mpn_sqrtrem2. I know how to improve mpn_sqrtrem2. For a 64-bit computer, start from a 32-bit approximation, say x, of 1/sqrt(a), which is already done by mpn_sqrtrem1. Then use Karp-Markstein's trick for the square root: y = approx(a*x) # 32-bit approximation of sqrt(a) t = a - y^2 return y + x/2*t # 64-bit approximation of sqrt(a) I will try to implement that. Paul _______________________________________________ gmp-devel mailing list gmp-devel@gmplib.org https://gmplib.org/mailman/listinfo/gmp-devel
