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mpfitfun [message #89054]

Sun, 20 July 2014 00:50

Nims
Messages: 8
Registered: February 2014

Junior Member

Hi
I am using mpfitfun for fitting a first order polynomial: y = ax+b. To calculate the error on the polynomial, I am using "perror" given by mpfitfun. Could someone tell me which of the two values of perror (perror[0] and perror[1]) corresponds to which coefficient (a and b)?
Thank you.

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Re: mpfitfun [message #89056 is a reply to message #89054]

Sun, 20 July 2014 08:02

Mats Löfdahl
Messages: 263
Registered: January 2012

Senior Member

Den söndagen den 20:e juli 2014 kl. 09:50:51 UTC+2 skrev Nims:
> Hi
>
> I am using mpfitfun for fitting a first order polynomial: y = ax+b. To calculate the error on the polynomial, I am using "perror" given by mpfitfun. Could someone tell me which of the two values of perror (perror[0] and perror[1]) corresponds to which coefficient (a and b)?
>
> Thank you.

That depends on the function that returns the function you are fitting, the name of which you passed to mpfitfun. If it returns p[0] + p[1]*X (which would make sense to me) then perror[0] corresponds the error in b and perror[1] the error in a.

But if you made it return p[0]*X + p[1], then the order of the errors is the opposite.

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