Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2004
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2004

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: MMA 5.1 Integrals

  • To: mathgroup at smc.vnet.net
  • Subject: [mg52838] Re: MMA 5.1 Integrals
  • From: Urijah Kaplan <uak at sas.upenn.edu>
  • Date: Tue, 14 Dec 2004 05:59:41 -0500 (EST)
  • Organization: University of Pennsylvania
  • References: <cpauqc$ipm$1@smc.vnet.net> <cpjnj9$n7r$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

nospam nospam wrote:
> Egbert Kankeleit wrote:
> 
> 
>>Someone with  elitist "insight" can understand  the philosophy
>>of costly updates? :
>>
>>Example (win2000, 850 MHz):
>>
>>i)     Timing[ FourierTransform[Exp[-(x + 1)^2] , x, X];]
>>
>>ii)     Timing[ Integrate[Exp[-(x + 1)^2 + I *x *X],
>>        {x, -\[Infinity],\[Infinity]}];]
>>
>>iii)     Timing[ LaplaceTransform[Exp[-(x + 1)^2], x, X];]
>>
>>results respectively:
>>         MMA 4.2,                  MMA 5.0            MMA5.1
>>
>>i)         1.4                    Infinity          117.       seconds
>>ii)        1.0                    45.                     1.9
>>iii)       0.15                    1.0                   1.0
>>
>>WRI,  quo vadis?
>>
>>kankel
>>
>>
> 
> 
> 
> You must have very old PC or something?
> I am running XP, and I tried the third test, and I get (my
> PC is almost 3 years old), this is Mathematica 5.1
> 
> d = Table[Timing[LaplaceTransform[Exp[-(x + 1)^2], x, X]][[1, 1]]
>      , {i, 100}];
> 
> Mean[d]
> 0.10094
> 
> Min[d]
> 0.078
> 
> Max[d]
> 0.11
> 
> so I get something faster than 4.2
> 
> You have to understand that the FIRST time you run the
> command, it can take as much as 10 times longer, since
> it will load the code to memory when needed. so get
> an accourate test, try the command once, then the
> second time will be the actual timing results you want to
> look at.
> 
> I found Mathematica to be very fast actually.
> 
> 
> 
> 
> 
I don't think that's what's is going on. I believe Mathematica is caching 
  some of the intermediate results, so Mathematica is not actually 
completely recalculating the result. In order to prevent that, you should 
use ClearCache[]. On an Athlon XP 1700+ and Mathematica 5.1;

d = Table[Developer`ClearCache[];
      Timing[LaplaceTransform[Exp[-(x + 1)^2], x, X]][[
       1,1]], {i, 100}];


{Mean[d], Min[d], Max[d]}

{0.47169,0.437,0.547}

             --Urijah Kaplan


  • Prev by Date: Re: Re: Needed Grid lines in Implicit Plot
  • Next by Date: Re: How to express ODE?
  • Previous by thread: Re: MMA 5.1 Integrals
  • Next by thread: Re : Partial fraction command