[SciPy-user] chi square value on leastsq
Fernando Avila Castro
favilac at cosmos.astro.uson.mx
Wed Jun 29 13:52:25 EDT 2005
>
> x, mesg = optimize.leastsq(f, x0, ...)
>
> chi2 = sum(power(f(x), 2))
>
Thanks, but i'm unable to adapt it to my code:
>>def residuals(p, y, x):
>> A,B,C = p
>> err = y - (A-B*(x**C))
>> return err
>>
>>def peval(x, p):
>> return (p[0] - p[1]*(x**p[2]))
>>
>>p0 = [ 1, 1, 1]
>>
>>from scipy.optimize import leastsq
>>plsq = leastsq(residuals, p0, args=(y_meas, x))
my guess is that the last line should be changed to
>>p, plsq = leastsq(residuals, p0, args=(y_meas, x))
>>chi2 =sum(power(residuals,2))
but it doesn't work.
What I'm doing wrong?
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