Fitting Fraunhofer Diffraction Data

[LogicalTime]

Homework Statement

Is there a good way to do a fit. The fft looks simple:

I am trying to fit data from my experiment to the very nonlinear nested sine function given as equation 3 here:
http://www.physics.umd.edu/courses/Phys375/HillSpring10/Labs/Lab5Diffraction.pdf

Homework Equations

see above

The Attempt at a Solution

I am using matlab, the model function is crazy! Though the data looks good in Fourier space.

 

[Rajini]

Try gnuplot, all in all it does a good fit.
it is just few minutes to do it. If you need help supply your data with the model function, i can try.
good luck