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help regarding curvefit [message #89833]

Mon, 08 December 2014 22:56

Krishnakumar M.A
Messages: 19
Registered: March 2013

Junior Member

Hello All,

I am trying to use the curvefit algorithm in IDL for fitting my data with a function as given in the code below. It is peacefully fitting and giving me the result, but only one problem, it is doing only one iteration and giving the same A=[] value as the fitted result. I'm not able to figure out what went wrong, and I have used cuurvefit before and it worked well. Do anybody have any idea to solve this issue?

Any help is appreciated....

Thanks,
Krishnakumar

code:

RO gfunct, X, A, F, pder

F = sqrt((!dpi^5.0 * A[0]^3.0) / (8 * x^5.0)) * exp( - (!dpi^2 * A[0]) / (4*x)) * 180.0

IF N_PARAMS() GE 1 THEN $ ; calculate the partial derivatives......

pder = [!dpi^5.0 * A[0] / (8*x^5.0) * exp(-!dpi^2.0 * A[0] / (4*x)) * 180.0* (1.5 - !dpi^2.0 * A[0]/ (4*x))]

END

openr,1,"data.dat"
xpy=fltarr(3,301)
readf,1,xpy
x=reform(xpy[1,*])
y=reform(xpy[2,*])

A=[100.0]

weights = 1.0/y^2.0

yfit=curvefit(x+10,y,weights,A,SIGMA,chisq=chisq,iter=it,fun ction_name='gfunct')
print,A,sigma,chisq,it
close,1

plot,x,yfit
oplot,x,y

end

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[Message index]

		help regarding curvefit By: Krishnakumar M.A on Mon, 08 December 2014 22:56
		Re: help regarding curvefit By: Heinz Stege on Tue, 09 December 2014 00:54
		Re: help regarding curvefit By: Craig Markwardt on Tue, 09 December 2014 12:19
		Re: help regarding curvefit By: Krishnakumar M.A on Tue, 09 December 2014 23:34

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