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matlablevenberg-marquardt

using options in lsqcurvefit

I set my options to

options=optimset('LevenbergMarquardt', 'on')

and then employ lsqcurvefit like below,

[x,resnorm,residual,exitflag,output] = lsqcurvefit(@myfun, [0.01 0.3], xdata, ydata, [-inf -inf], [inf inf], options)

but the problem is that I don't now why I will get for output :

output = 

firstorderopt: 3.4390e-07
   iterations: 4
    funcCount: 15
 cgiterations: 0
    algorithm: 'large-scale: trust-region reflective Newton'
      message: [1x425 char]

Does this mean Matlab did not use the algorithm Levenberg Marquardt?

But I did set my options to levenberg Marquardt algorithm!!!

I'd appreciate any help.

Solution

  • Sometimes a specific algorithm is not suitable for a specific configuration of an optimization problem. In these cases Matlab "falls back" to its default optimization algorithm.
    It might be the case that for your specific problem/configuration Matlab is unable to use Levenberg-Marquardt algorithm.

    Read the docs carefully to see if this is the case.