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Re: help with mathematics [message #80306]

Wed, 30 May 2012 22:09

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

On May 30, 3:24 pm, Russell Ryan <rr...@stsci.edu> wrote:
> On May 30, 8:52 am, nata <bernat.puigdomen...@gmail.com> wrote:
>
>> Thank you for reply Russell ! I am already reading the documentation for curvefit. I will try to solve the equation as you say...
>> These mathematical things are not obvious to me and sometimes I don't know what to do to solve this kind of problems.
>
>> Anyway, I will let you know if I don't find a good fit.
>> Thank you,
>
>> nata
>
> Hi nata,
> on a hunch I did the curvefit thing last night. The results don't
> really look very good, and it makes me wonder if the model is not very
> good....

I did this... (using my MPFIT package)
Rinit = [1,1,1.]
expr = '(P[0] + P[1]*X + P[2]*X^2 + ((1-P[1]-4*P[2])/12)*X^3)'
R = mpfitexpr(expr,x,y,1.0,Rinit, yfit=yfit)
plot, x,y
oplot, x, yfit, color='ff'xl

... and you're right, it doesn't look like a good model fit.

Craig

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[Message index]

		Re: help with mathematics By: Craig Markwardt on Wed, 30 May 2012 22:09
		Re: help with mathematics By: Russell Ryan on Wed, 30 May 2012 12:24
		Re: help with mathematics By: natha on Wed, 30 May 2012 05:52
		Re: help with mathematics By: Russell Ryan on Mon, 28 May 2012 21:02
		Re: help with mathematics By: natha on Thu, 31 May 2012 05:55

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