Re: V8 slow like a snail

*To*: mathgroup at smc.vnet.net*Subject*: [mg127732] Re: V8 slow like a snail*From*: "Alexey Popkov" <lehin.p at gmail.com>*Date*: Fri, 17 Aug 2012 03:45:24 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <k0fjaj$q71$1@smc.vnet.net>

"Dr. Wolfgang Hintze" <weh at snafu.de> ÓÏÏÂÝÉÌ/ÓÏÏÂÝÉÌÁ × ÎÏ×ÏÓÔÑÈ ÓÌÅÄÕÀÝÅÅ: news:k0fjaj$q71$1 at smc.vnet.net... > Great disappointment on my side with 8.0.4.0 Home edition which I > installed yesterday! > My first impression: looks good, many nice features ... but incredibly > slow in comparision to my good old 5.2. > I then carried out a modest benchmark test the results of which I'll > show below and which I like to express in terms of a "snail > factor" ( = time in v5.2/ time in v8). > > Consider this integral for which we can safely expect Mathematica to > be expert in solving: > > f1[n_, m_] := > Integrate[n t^m Exp[-n t] (Exp[t] - 1)^(n - 1), {t, 0, \[Infinity]}, > Assumptions -> {{n, m} \[Element] Integers, m >= 0, n > 0}] > > I carried out Timing[f1[n, m]] for m=0,1,2,3,10 in both versions. Here > are the results in the format > > {m, V5.2 f1 first call, V5.2 second call, V8 first call, V8 second > call, snail factor first call, snail factor second call} > > { > { 0, 0.328, 0.078, 2.122, 2.044, 6.46951, 26.2051}, > { 1, 0.109, 0.063, 30.202, 30.483, 277.083, 483.857}, > { 2, 0.421, 0.11, 30.42, 30.17, 72.2565, 274.273}, > { 3, 0.452, 0.156, 31.528, 31.325, 69.7522, 200.801}, > {10, 5.366, 5.382, 42.448, 42.682, 7.91055, 7.93051} > } > > Even if we compare only the first calls the range of the snail factor > goes up to 277 at m = 1, is 72 for m = 2, and is still close to 8 for > larger m. > > This is my story in other words: I own a very old car, and have > considered for a long time to change to a newer one - although it > still can go at 200 km/h on the Autobahn. > So now I am proud owner of the new brilliant car, and I must learn the > on important tours (m=1) =EDts maximum speed turns out to be less than 1 > km/h, about 3 km/h (m=2) or at most about 30 km/h. Who laughes? Me > not! Obviously I'll definitely keep the old car! > > Ok, maybe I have chosen the wrong example (though in other test runs a > similar pictures emerged and this example is just the type I'm using > Mathematica for). Are there perhaps acknowleged benchmarks for such a > comparison of versions? > > Finally, dear group, as you might have noticed, I'm asking for > consolation. Please comment and give me useful hints. Many thanks in > advance. > > Best regards, > Wolfgang > There is a way to use MathKernel of version 5.2 from the version 8 transparently via MathLink. It is as easy as defining f1[n_, m_] := krn5Eval[Integrate[n t^m Exp[-n t] (Exp[t] - 1)^(n - 1), {t, 0, \[Infinity]}, Assumptions -> {{n, m} \[Element] Integers, m >= 0, n > 0}]] (where krn5Eval[] is a function that transparently uses version 5 for evaluating its argument). You can find more information in this thread: http://stackoverflow.com/questions/4983301/executing-code-in-v-5-2-kernel-from-within-v-7-01-session-through-mathlink HTH, Alexey