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Re: numerical integration

  • To: mathgroup at smc.vnet.net
  • Subject: [mg110639] Re: numerical integration
  • From: Bill Rowe <readnews at sbcglobal.net>
  • Date: Wed, 30 Jun 2010 01:49:12 -0400 (EDT)

On 6/29/10 at 8:39 AM, ofershl at gmail.com (ofer) wrote:

>thanks peter. actually i don't get error messages but warnings like
>:

>NIntegrate::slwcon: Numerical integration converging too slowly; \
>suspect one of the following: singularity, value of the integration
>\ is 0, highly oscillatory integrand, or WorkingPrecision too small

So, try increasing WorkingPrecision or trying a different method
or both. No matter what is chosen for the default settings of a
numerical integration routine, they will never be adequate for
all possible integrals. NIntegrate allows for quite a bit of
customization in terms of precision, accuracy and methods used
to perform the integration.

>and the result i get is far from the accurate result obtained via
>analytic methods

Well the error message is stating there is a problem with
convergence. So, why would you expect the result to be accurate
with that error message? And if you have an accurate result
obtained by analytic methods, why bother with NIntegrate any further?

Doing integration problems is hard. It should never be
surprising that the built-in routines with default settings fail
for some integrals.



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