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MathGroup Archive 2012

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FindRoot and parameters in NIntegrate

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124488] FindRoot and parameters in NIntegrate
  • From: gac <g.crlsn at gmail.com>
  • Date: Sat, 21 Jan 2012 05:18:00 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

I am using Mathematica 8 to solve for parameters in an integral and an auxiliary equation.  A prototypical problem is

FindRoot[{1 + a + b , NIntegrate[a + b x, {x, 0, 1}]}, {{a, 0}, {b, 0}}]

Mathematica reports the correct answer for the parameters a and b: 

{a -> 1., b -> -2.}

But it also reports two error messages:

NIntegrate::inumr: The integrand a+b x has evaluated to non-numerical values for all sampling points in the region with boundaries {{0,1}}. >>

NIntegrate::izero: Integral and error estimates are 0 on all integration subregions. Try increasing the value of the MinRecursion option. If value of integral may be 0, specify a finite value for the AccuracyGoal option. >>

I would appreciate any advice or comments on this problem or the error messages. 

Thanks.

gac



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