"Carlos Alejandro Perez Lasso" <email@example.com> wrote in message <firstname.lastname@example.org>... > Hi Matlab users, > > My purpose is to use the Optimtool to estimate material model parameters so that running the model with such parameters in Abaqus results in a predicted curve close to some experimental data. > I am trying to solve the problem with the lsqnonlin solver ============
If it's a curve fitting problem, mightn't it be better to use lsqcurvefit.
> Optimization completed because the size of the gradient at the initial point > is less than the default value of the function tolerance. ==========
This usually occurs because you have quantizing operations like ROUND, FLOOR, CEIL, etc... in your objective function. They make the function locally flat in places, making the initial point trivially a point of zero gradient.