How do I constrain a vector's value within a nonlinear fit?

I am fitting a set of data using nlinfit as magnetic dipoles and I want my fitted parameters to be only positive.

How do I make this constraint?

Answer 1

[Torsten]

Put them in the fittype equation as parameters-squared.

Best wishes

Torsten.

[matlabkid602]

Could you please explain further, square the parameters then sqrt?

[Torsten]

Yes, put the parameters squared in the fittype function and square the results after solving.

Best wishes

Torsten.

[matlabkid602]

Thank you, it works.