On Thu, 20 Mar 2008, Axel Simon wrote: > I need to use the lpx_exact function and find that the performance on > repeatedly running a 100x10 variable problem is about 70x slower than > using doubles. It turns out that the program spends 40% of it's time > calculating the gcd when canonicalizing fractions. Is there a way to use > integers (rather than rationals) to represent the coefficients of a row > rather than rationals? I would assume that this is possible since a row > can always be scaled by the smallest denominator. Normalizing a row > could be much cheaper since the gcd calculation can be aborted early > whenever the gcd drops to 1. > > Am I missing something?
You could end up with rather large divisors, e.g. near the determinant of the basis. You might try starting with doubles and feed the optimal basis to lpx_exact. -- Michael [EMAIL PROTECTED] "Those parts of the system that you can hit with a hammer (not advised) are called Hardware; those program instructions that you can only curse at are called Software." _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk
