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How are initial values chosen for either lsqcurvefit or nlinfit functions?
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I want to fit my experimental data to a theoretical model which contains an exponential. I've attached a copy of the code I'm using. I've tried various x0 matrix values, but the same error message keeps popping up:
Caused by: Failure in initial objective function evaluation. LSQCURVEFIT cannot continue.
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Answers (3)
Torsten
on 19 Sep 2018
There must be some mathematical operation within your objective function that gives Inf, NaN or something similar (e.g. division by zero, log or sqrt of a negative number, exponentiation of a negative number ...).
Best wishes
Torsten.
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Ken Mathai
on 19 Sep 2018
Edited: Walter Roberson
on 19 Sep 2018
3 Comments
Torsten
on 19 Sep 2018
Linear means: The equation is linear in the parameters.
It is irrelevant how "xdata" enters the equation.
Thus in your case x(1) and x(2) are simply given by
x = [xdata xdata.^2]\ydata
where xdata and ydata are your respective column vectors.
Best wishes
Torsten.
Ken Mathai
on 19 Sep 2018
1 Comment
Torsten
on 20 Sep 2018
It should suffice to have the Optimization Toolbox (lsqcurvefit, fmincon,...)
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