exponential fitting?

Mario — Fri, 26 Sep 2008 17:20:04 -0400

Hi..
I'm dealing with this kind of data

x=[527.3756 546.1192 564.9728 586.4216 608.2959 630.5845 652.8730 674.8214 697.0359]

y=[193 204.1192 214.9728 219 222 224 222 219.1786 217]

and i would like to fit a*(1-exp(b*x)) (because i think it's the best curve that fits these points) and i tried to do it but i didn't get a good fit! What am i doing wrong?
I even tried to scale the data in order to place the first point in [0,0] but it didn't work as i expected (the exponential curve fit the points after it grows, so it fits the point with a line almost)

Hope you can help me!
Regards,

Mario

Re: exponential fitting?

Richard — Fri, 26 Sep 2008 17:41:02 -0400

Using the curve fitting toolbox, an exponential model of the form
a*exp(b*x)+c*exp(d*x)

"looks" like it fits well enough.

"Mario " <nospam@yahoo.com> wrote in message <gbj5k4$5fa$1@fred.mathworks.com>...
> Hi..
> I'm dealing with this kind of data
>
> x=[527.3756 546.1192 564.9728 586.4216 608.2959 630.5845 652.8730 674.8214 697.0359]
>
> y=[193 204.1192 214.9728 219 222 224 222 219.1786 217]
>
> and i would like to fit a*(1-exp(b*x)) (because i think it's the best curve that fits these points) and i tried to do it but i didn't get a good fit! What am i doing wrong?
> I even tried to scale the data in order to place the first point in [0,0] but it didn't work as i expected (the exponential curve fit the points after it grows, so it fits the point with a line almost)
>
> Hope you can help me!
> Regards,
>
> Mario

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exponential fitting?

Re: exponential fitting?