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RE: Problems with FindMinimum

• To: mathgroup at smc.vnet.net
• Subject: [mg90738] RE: Problems with FindMinimum
• From: "Teodoro Marinucci" <teodorom at hotmail.com>
• Date: Tue, 22 Jul 2008 03:57:11 -0400 (EDT)
• References: <g5v5mf$ia9$1@smc.vnet.net> <488371B2.3020604@gmail.com>

Merci Jean-Marc,
unfortunately the exponential (Z0 in the following) is 3/2, not 2/3. 
When one is lucky ... because in the most general case the exponential 
is a real number (between 1 and 1.5).
The function I'm trying to fit with the experimental data (that are 
supplied in Vgk[[i]] and Vak[[i]])
is

is[Vgk_,Vak_,Z0_,G0_,G1_,G2_, 
G3_,mu0_,mu1_,mu2_,mu3_,H0_,H1_,H2_,H3_]:=(G0+G1 Vgk+G2 Vgk^2+G3 Vgk^3 
) (Vgk+Vak/(mu0+mu1 Vgk+mu2 Vgk^2+mu3 Vgk^3)+H0+H1 Vgk+H2 Vgk^2+H3 
Vgk^3)^Z0

It has a lot of parameters, I know, but usually

G0>>G1>>G2>>G3

and so on, so I could, in principle, attempt a perturbative approach. 
Unfortunately I get the same error even if I start from a enough good 
solution (enough near fit).
Thanks again
		Teodoro Marinucci


-----Original Message-----
From: Jean-Marc Gulliet [mailto:jeanmarc.gulliet at gmail.com]
Sent: domenica 20 luglio 2008 19.11
To: teodorom at hotmail.com; mathgroup at smc.vnet.net
Subject: [mg90738] Re: Problems with FindMinimum

teodorom at hotmail.com wrote:

> I'm having problems with the FindMinimum.
> I'm currently getting errors like this:
> FindMinimum::nrlnum: The function value {0.335521+43899.8 \
> [ImaginaryI],0.376043+43899.8 \[ImaginaryI],0.424669+43899.8 \
> [ImaginaryI],<<6>>,0.311208+46311.9 \[ImaginaryI],<<27>>} is not a
> list of real numbers with dimensions {37} at {x0,y0,x1,y1,hh0,hh1} 
> 
{0.00580647,-2.13969*10^20,-9.86301*10^-6,1.23875*10^20,-30574.3,19.6042}