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Re: How to fit like-elliptical funcion?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg51566] Re: How to fit like-elliptical funcion?
  • From: astanoff_otez_ceci at yahoo.fr (astanoff)
  • Date: Sat, 23 Oct 2004 00:21:47 -0400 (EDT)
  • References: <cl9s12$7f1$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Andriy Krasowsky wrote:

> Hallo everybody,

> does anyone knows how to fit an equation like

> (x/P1)**a + (y/P2)**b = 1

> on data which are in the first quadrant? P1, P2, a, b are to fit.

> Thanks a lot in advance

> Andriy

--
Example :

<<Statistics`NonlinearFit`

 data={{10.,0.1,1.},{9.5,1.5,1.},{9.,3.,1.},
{7.,3.5,1.},{6.,3.75,1.},{5.,4.,1.},{0.1,4.,1.}};

NonlinearFit[data,(x/P1)^a+(y/P2)^b,{x,y},{a,b,P1,P2}]

0.00124842*x^2.916375 + 0.00559693*y^3.700292

hth

v.a.
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