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Using fit 'exp2' an error with "weights"

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JJC
JJC on 12 Apr 2013
Commented: Zahra Ali on 2 Nov 2017
I've used the fit function a few times on creep data sets (i.e. time vs displacement) and have been using the 'exp2' fit type. On smaller data sets I've had no problem using this function. Now I'm looking at a 10 folder bigger data set and am getting an error.
I was previously running this and had no problem
[creep_data_fit, gof] = fit(creep_data(1:1800,1),creep_data(1:1800,2), 'exp2')
Now I'm running this and getting the following error
[creep_data_fit, gof] = fit(creep_data(1:10800,1),creep_data(1:10800,2), 'exp2')
Any ideas on why i'm getting this error?
Error using fit>iFit (line 235)
X, Y and WEIGHTS cannot have NaN values.
Error in fit (line 109)
[fitobj, goodness, output, convmsg] = iFit( xdatain, ydatain, fittypeobj, ...

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Answers (2)

Tom Lane
Tom Lane on 13 Apr 2013
Since you didn't specify weights, it seems like the NaN value must be in either x or y. You can find the usable values (using your own variable names) like this:
t = ~isnan(x) & ~isnan(y);
Then omit the NaN values from the fit:
fit(x(t),y(t),'poly1')

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Alison
Alison on 16 Apr 2013
This worked great. Thanks Tom.

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Alison
Alison on 16 Apr 2013
This worked great thanks Tom!

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Zahra Ali
Zahra Ali on 2 Nov 2017
I had been working on something similar for a very long time, thank you for your help!

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