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 Author Comment/Response Matt Labrum 03/23/08 00:43am Hello, I have put together the following code for some number crunching work I'm doing, and I am trying to figure out why it is running so slowly. -----Begin Code----- RandPoi[\[Mu]_] := RandomInteger[PoissonDistribution[\[Mu]]] extTimes[T_, \[Mu]1_, \[Mu]2_, s_, \[Lambda]_, q0_, N0_, runs_] := Module[{N1, N2, tmpN1, tmpN2, lstTimes}, lstTimes = Reap[ For[i = 0, i < runs, i++, N2 = Round[N0*q0]; N1 = N0 - N2; For[j = 1, j <= T, j++, tmpN1 = 0; tmpN2 = 0; For[k = 0, k < Max[N1, N2], k++, If[k < N1, tmpN1 += RandPoi[(1 - \[Mu]1)*(1 + s)*\[Lambda]]; tmpN2 += RandPoi[\[Mu]1*(1 + s)*\[Lambda]] ]; If[k < N2, tmpN1 += RandPoi[\[Mu]2*\[Lambda]]; tmpN2 += RandPoi[(1 - \[Mu]2)*\[Lambda]] ] ]; N1 = tmpN1; N2 = tmpN2; If[Or[N1 + N2 >= 10*N0, j == T], Sow[T]; Break[] ]; If[N1 + N2 <= 0, Sow[j]; Break[] ] ] ] ][[2]][[1]]; Return[lstTimes] ] -----End Code----- Running the command: Timing[output = extTimes[100000, 0.002, 0.002, 0.02, 0.9825, 0.75, 1000, 20]] gives the following output (for example): {24523.4, {622, 319, 623, 100000, 100000, 2459, 1163, 1070, 381, 100000, 1259, 100000, 100000, 1117, 329, 264, 100000, 309, 568, 300}} Note that the running time is approximately 6.8 hours. Everything in each of the loops seems to be simple arithmetic, so I am not seeing why the execution time should be so long. I have coded the same thing in C++ and when I use the same set of parameters, I get very similar results, but the total execution time is around 5 minutes. If comp specs matter much, I'm on a MacBook Pro running Mac OS X Version 10.5.2 with a 2.6 GHz Intel Core 2 Duo processor and 2 GB 667 MHz DDR2 SDRAM. I'm using Mathematica 6.0.2.0 for Students which is running as an Intel process (with MathKernel running as an Intel (64 bit) process). Thanks, Matt URL: ,

 Subject (listing for 'Mathematica running slowly') Author Date Posted Mathematica running slowly Matt Labrum 03/23/08 00:43am Re: Mathematica running slowly yehuda ben-s... 03/24/08 01:07am Re: Re: Mathematica running slowly yehuda ben-s... 03/24/08 2:27pm
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