# Fitting data to integral function

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Sergio Quesada on 4 Jun 2018
Commented: Sergio Quesada on 4 Jun 2018
Hi everybody. I'm trying to fit an essemble of data ("r" as x and "texp" as y) by a function defined by an integral:
FC*integral(@(x)exp(-a./x.*log(x)),1,texp)
, were both "FC" and "a" are the parameters to fit, while "texp" are the upper integration limits, which must be equal to the "y" parameters at each point.
Thank you so much !
##### 2 CommentsShowHide 1 older comment
Walter Roberson on 4 Jun 2018
What should the expression equal?? Is it
texp = FC*integral(@(x)exp(-a./x.*log(x)),1,texp)
?

Sergio Quesada on 4 Jun 2018
Exactly, i hace a collection of data (xi,yi) called (r,texp), and the fitting equation must be
texp(r)=FC*integral(@(x)exp(-a./x.*log(x)),1,texp)
thanks!
Walter Roberson on 4 Jun 2018
Where is your independent variable appearing in the model? Is texp(r) intended to convey "the texp that corresponds to r", or is texp somehow intended to be both a function to be applied to r on the left side, but a particular numeric value on the right hand side where it is acting as the upper bounds of the integral ?
Or is texp(r) intended to be multiplication, as in
texp(K) * r(K) == FC * integral(@(x)exp(-a./x.*log(x), 1, texp(K))
and thus
texp(K) == FC / r(K) * integral(@(x)exp(-a./x.*log(x), 1, texp(K))

Sergio Quesada on 4 Jun 2018
Edited: Sergio Quesada on 4 Jun 2018
"texp" is my independent variable.
I have a collection of (r,texp) data. I have evaluated
FC*integral(@(x) -a./(x*log(x)),1,texp)
for each texp as upper integration limit with arbitrary values of "a" and "FC". Now i need to find the values of " a" and "FC" that best fits the experimental data
Sergio Quesada on 4 Jun 2018
success! i am so grateful Walter! This works thanks to people like you!
best regards