WOLFRAM

Services & Resources / Wolfram Forums / MathGroup Archive

MathGroup Archive 2005

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

Search the Archive

Quite Upset with NIntegrate

  • To: mathgroup at smc.vnet.net
  • Subject: [mg54142] Quite Upset with NIntegrate
  • From: ituran at bohr.concordia.ca (I. Turan)
  • Date: Fri, 11 Feb 2005 03:34:40 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com
Hi:

I have been trying to evaluate a 4-dimensional integral by using
NIntegrate with Mathematica 4 w2k.  The integrand and even the
integration limits are quite complicated (depending on int.
variables). The length of the integrand is around 2000 lines in the
FortranForm.

If I don't play with any options of NIntegrate, It takes one day to
get one data point and gives very  unreasonably weird values. By
setting, however, MaxPoints something like 100000 it is possible to
get faster results but still it seems that Mathematica couldn't handle
it. When I draw a figure from these data points, it appears very very
spiky such that it is even not possible to fit the curve. However, it
is supposed to be very smooth.

Should I accept that Mathematica can not handle such a 
numerical integration or is there a way to make Nintegrate working
better?

Thanks a lot,

Ismail
  • Prev by Date: Re: Derivative of g(z) = Arg(z) and f(z) = Re(z) + Im(z)?
  • Next by Date: Creating beta multivariate random variables
  • Previous by thread: Re: Create Permanent Self Defined Function?
  • Next by thread: Re: Quite Upset with NIntegrate