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2.2 Function nonlin_curvefit() for curve fitting

In curve fitting, the model function computes values from a constant set of ‘independents’, and the intention is to minimize the differences of these computed values to a constant set of ‘observations’. This can be done with nonlin_residmin, but it is more convenient to use nonlin_curvefit, which cares for passing the constant ‘independents’ to the model function and for calculating the differences to the constant ‘observations’.

However, if in some optimization problem you notice that you end up with passing dummy-values for the ‘independents’ and zeros for the ‘observations’, you can more naturally use nonlin_residmin instead of nonlin_curvefit.

Function File: [p, fy, cvg, outp] = nonlin_curvefit (f, pin, x, y)
Function File: [p, fy, cvg, outp] = nonlin_curvefit (f, pin, x, y, settings)

Frontend for nonlinear fitting of values, computed by a model function, to observed values.

Please refer to the description of nonlin_residmin. The differences to nonlin_residmin are the additional arguments x (independent values, mostly, but not necessarily, an array of the same dimensions or the same number of rows as y) and y (array of observations), the returned value fy (final guess for observed values) instead of resid, that the model function has a second obligatory argument which will be set to x and is supposed to return guesses for the observations (with the same dimensions), and that the possibly user-supplied function for the jacobian of the model function has also a second obligatory argument which will be set to x.

See also: nonlin_residmin.

Also, if the setting user_interaction is given, additional information is passed to these functions, see Common optimization options.


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