[Scilab-users] Problem with function fitting

[Maihem]

Hi,

I have problem with fitting function to measured data using scilab. I tried
scilab function datafit(), lsqrsolve(), leastsq() but none returns me a
proper result or can't perform calculations.

//I have measured data:
xm;ym
2.0;99.9449173761
1.0;99.8097145719
0.5;97.9769654482
0.25;36.4046069104
0.1;1.4872308463
0.071;0.5207811718
0.063;0.3705558338

//Script used to fit data

miny=min(ym);
maxy=max(ym);
minx=min(xm);
maxx=max(xm);

Zz=[xm;ym];

//Function describing problem (I want to find best fit by finding n()).

function g1=f1(x, n)
g1 = miny+((maxy-miny) ./((1+(n(1).*(x ./n(2)).^n(3))+(1-n(1)).*((x
./n(2)).^n(4)))).^n(5))
endfunction

function e = G(n,z)
  xm = z(1)
  ym = z(2)
  e = ym - f1(xm,n)
endfunction 

n0 = [1 ; 1; 1; 1; 1]
[n0_opt,err] = datafit(G,Zz,n0) 

After calling function scilab returns me error:
Variable returned by scilab argument function is incorrect.

I tried to find solution for this problem in scilab mailing lists and tried
some posted scripts and advices but I can't localize problem.


Łukasz



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