Re: Is Mathematica v8 slower than v7 ?

*To*: mathgroup at smc.vnet.net*Subject*: [mg126515] Re: Is Mathematica v8 slower than v7 ?*From*: David Bailey <dave at removedbailey.co.uk>*Date*: Wed, 16 May 2012 04:23:37 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <jonm9a$gdk$1@smc.vnet.net>

On 13/05/2012 08:02, perplexed wrote: > I have tried Mathematica 8.0.4 for Windows on a laptop > running Vista Ultimate 64-bit with a T9400 (at 80% speed). > There was a previous version (7.x.x) that I have uninstalled > (so I cannot do more tests...). > > Anyway, before uninstalling, since I was curious about the > relative performance of the two versions, I have saved a notebook > with a few line of code (each repeated at least 3 times). > > Here are two examples: > Timing[Select[Range[5 10^5], EulerPhi[#] + # == DivisorSigma[1, #]&]] > (* v7 about 12 seconds, v8 13.4 seconds, i.e. about 10% slower *) > > Timing[Select[Range[12], Reduce[x^2 - # y^2 == 1 + x y&& x> 0&& y> 0, > {x, y}, Integers] === False&]] > (* v7 about 10.1 seconds, v8 14 seconds, about 35% slower *) > > In another case v8 was much faster: > Timing[Sum[N[1/x] Log[x], {x, 2, 10^6}]] > (* v7 about 7.6 seconds, v8 about 0.2 seconds i.e. > about 35 times faster *) > > To be honest, my interest in Windows version is marginal (the laptop > is just for emergencies) since our official Mathematica > licence is for linux, but I'm still wondering if upgrading to v8 > can be useful even if one is not interested in all the new > features. > > thanks > I don't think there is much point comparing the speed of symbolic calculations from version to version, because later versions may contain extra rigorous checks - this is certainly the case with certain symbolic definite integrals. Changes in speed will obviously vary depending on what exactly you test. In general, I would imagine you would see the same relative speed changes under Linux as you do under Windows (assuming both systems have adequate memory) because almost all the code will be the same. David Bailey http://www.dbaileyconsultancy.co.uk