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Curvefit [message #9041]

Wed, 21 May 1997 00:00

zanotti
Messages: 5
Registered: May 1997

Junior Member

Hi,

I use CURVEFIT (on PV-WAVE CL Version 6.05 (sun4 solaris sparc)) to perform non-linear least sqares fitting. It works rather well, but once the fit is performed, the vector of standard deviations for parameters (named Sigmaa) seems to give very large values:
for a given set of data, the error on parameters is ten times greater with Curvefit than, for exemple, with Kaleidagraph.

In fact, Curvefit is based on the Gradient-expansion algorithm, and the way the programm calculates the error (i.e SIGMAA = SQRT(ARRAY(DIAG)/ALPHA(DIAG)) ) is perharps wrong (something missing ???).

Does anybody has an idea ?

Thanks for help.

J.Marc

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_/_/_/_/ Jean-Marc Zanotti _/ _/_/_/
_/_/_/_/ Laboratoire Leon Brillouin _/_/_/_/
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[Message index]

		Curvefit By: zanotti on Wed, 21 May 1997 00:00
		Re: Curvefit By: thompson on Wed, 21 May 1997 00:00
		Re: curvefit By: David Fanning on Tue, 07 January 2003 20:13
		Re: CURVEFIT By: Craig Markwardt on Wed, 02 June 2004 11:40
		Re: CURVEFIT By: K. Bowman on Wed, 02 June 2004 08:56
		Re: curvefit By: Paolo Grigis on Tue, 14 June 2005 09:16
		Re: curvefit By: nolan.smith1 on Tue, 14 June 2005 08:20
		Re: curvefit By: nolan.smith1 on Mon, 13 June 2005 21:02
		Re: curvefit By: nolan.smith1 on Mon, 13 June 2005 20:07
		Re: curvefit By: Craig Markwardt on Mon, 13 June 2005 15:24
		Re: curvefit By: kashyap on Mon, 13 June 2005 14:50
		Re: curvefit By: nolan.smith1 on Mon, 13 June 2005 12:59
		Re: curvefit By: Benjamin Hornberger on Mon, 13 June 2005 12:46

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