Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2006
*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 2006

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

Search the Archive

Re: adding assumptions to Integrate

  • To: mathgroup at smc.vnet.net
  • Subject: [mg69649] Re: [mg69630] adding assumptions to Integrate
  • From: Andrey <newsgroup at gorodok.net>
  • Date: Tue, 19 Sep 2006 05:45:10 -0400 (EDT)
  • References: <200609180246.WAA09330@smc.vnet.net>
  • Reply-to: Andrey <newsgroup at gorodok.net>

> However I do not understand why exist the big difference in times
> below.

> Timing[Assuming[Re[m] > 0 && Re[n] > 0, Integrate[BesselJ[n, x]/(1 +
> x)^m,
> {x, 0, Infinity}]]][[1]]
> 39.71900000000001*Second

> Timing[Integrate[BesselJ[n, x]/(1 + x)^m, {x, 0, Infinity}, Assumptions
->>
Re[m] >> 0 && Re[n] > 0]][[1]]
> 15.859000000000009*Second

> Timing[Block[{$Assumptions = Re[m] > 0 && Re[n] > 0},
> Integrate[BesselJ[n, x]/(1 + x)^m, {x, 0, Infinity}]]][[1]]
> 8.734000000000009*Second

> old$Assumptions = $Assumptions;
> $Assumptions = Re[m] > 0 && Re[n] > 0;
> Timing[Integrate[BesselJ[n, x]/(1 + x)^m, {x, 0, Infinity}]][[1]]
> $Assumptions = old$Assumptions; Clear[old$Assumptions]
> 6.891000000000005*Second

> I will really appreciate any kind of guidance.

> Dimitris Anagnostou

If you will quit kernel after each execution you will see that
necessary times are almost equal (for me it is 30 sec) (don't forget to
load kernel by executing something)

Andrey B.


  • Prev by Date: Re: Question about the special \n
  • Next by Date: Re: package in separate files
  • Previous by thread: adding assumptions to Integrate
  • Next by thread: Re: adding assumptions to Integrate