Least squares solvers - Optimization Toolbox

I am working on the least square method using the otimization toolbox.

I would like to know the difference between lsqnonlin solver and lsqcurvefit solver ? I would also appreciate to know the meaning of the output values of: "funccount", "norm of step" and "first order optimality".

Thank you, in advance.

Answer 1

[Matt J]

The only difference between the two solvers is the input syntax. lsqcurvefit has the more convenient syntax when the residuals are of the form,

resid = F(theta,x) - y

Explanations for the iterative display headings can be found here:

https://www.mathworks.com/help/optim/ug/iterative-display.html

[Sana KHALED]

Right, they differ in the input syntax, but since they both rely on the same algorithms (trust-region algorithm/levenberg-marquardt), then why don't they give the same values for the output parameters? That would mean that the calculation is not the same either, right?

Thank you.