Date: Dec 10, 2012 7:43 AM
Author: ariel
Subject: Re: fitting ( cftool )

"Steven_Lord" <slord@mathworks.com> wrote in message <ka3mcf$cs1$1@newscl01ah.mathworks.com>...
>
>
> "ariel " <arn335@msn.com> wrote in message
> news:k9veu1$7s$1@newscl01ah.mathworks.com...

> > im trying to do a fitting between a vector and a function .
> > my vector is a intensity summed by 20 degree angle (160-180) as a function
> > of the beam radius, as the following pics describe : this is the picture :
> > http://postimage.org/image/baff0lf63/
> > the imagesc pic after cutting by angle plus intensity graph by radius (
> > the angle is summed ) : http://postimage.org/image/s9l2d8j5b/
> >
> > my try to to do fitting with cftool :
> > http://postimage.org/image/6so1ugaeh/
> >
> > the function i try to do fitting with : sin(b*sin(atan(x./0.05)).^2).^2+c
> > which i took from theory .
> > as you can see the fitting is total joke, and ideas ?

>
> 1) My guess is that the Curve Fitting window told you that there was some
> difficulty with the fit. If so, what did it say?
>
> 2) How certain are you of your function? From the image of your data it
> looks more like a sinusoidal times a quadratic or something similar. Taking
> sine of sine of arctangent seems odd to me.
>


1) didnt get any error message .

2) 99% sure, in the books the forumla appears without atanx but with X but the X in the books equalts to atan(x'/0.05) when x' is the x' in my data (came from simple geometry)

any ideas?