Re: Division still cost more than multiplication?

*To*: mathgroup at smc.vnet.net*Subject*: [mg24303] Re: Division still cost more than multiplication?*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Fri, 7 Jul 2000 00:11:45 -0400 (EDT)*Organization*: Universitaet Leipzig*References*: <8k0tc4$q2o@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, Timing[x = 1; c = N[\[Pi]]; cInverse = 1/c; Do[y = x*cInverse, {10000}]] {0.26 Second, Null} Timing[x = 1; c = N[\[Pi]]; cInverse = 1/c; Do[y = x/c, {10000}]] {0.41 Second, Null} The multipication/division algorithm has not changed since several hundred years -- what are long-gone days for you ? You can stopp the time by hand *you* need to multiply two numbers and to divde the numbers. Regards Jens AES wrote: > > Old-time FORTRAN programmers (like me) were taught (at least in early > days) that division cost a lot more machine cycles than multiplication. > So, if you had an expression like y = x/c that was going to be called > many times inside a loop, where x and y were variables and c a constant, > you'd code this as: > > (Outside the loop) > > cInverse = 1/c; > > (Begin loop structure) > > y = cInverse * x > > Does this still make any sense in Mathematica? Or is it a primitive > relic of long-gone days?