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NonlinearRegress fitfail error

  • To: mathgroup at smc.vnet.net
  • Subject: [mg89333] NonlinearRegress fitfail error
  • From: Meaghan <FreeCaptive6914 at gmail.com>
  • Date: Fri, 6 Jun 2008 06:46:06 -0400 (EDT)

I'm updating an old program to Mathematica 6.  Here's the problem
code:

Needs["NonlinearRegression`"]

msoln = BestFitParameters /.
  NonlinearRegress[part1, a2*(Exp[b2*x] - 1) + c2*x, startpoints, x,
   AccuracyGoal -> 5, PrecisionGoal -> 5, MaxIterations -> 500,
   RegressionReport -> BestFitParameters]
where "part1" is a long list of data points.

I know this method of replacement was valid in 5.2, but here I get:
FindFit::nrlnum: The function value {0.+(-1.+2.71828^(0. b2)) a2+0.
c2,0.104632+(-1.+2.71828^(0.195816 b2)) a2+0.195816 c2,<<8>>,<<92>>}
is not a list of real numbers with dimensions {102} at {a,b,c} =
{0.0369002,0.32,0.158379}.
NonlinearRegress::fitfail: The fitting algorithm failed.
ReplaceAll::reps: "{msoln} is neither a list of replacement rules nor
a valid dispatch table, and so cannot be used for replacing."

Thank you for the help!


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