Hi Jonathan Trueblood,
Levenberg-Marquardt-Algorithm is built-in into lsqcurvefit(), Optimization Toolbox. You would have to define its use by setting options accordingly (cf. optimoptions()):
options = optimoptions('lsqcurvefit','Algorithm','levenberg-marquardt');
Then define your custom function in any way (anonymous, nested or external). Examples, on how to use lsqcurvefit() can be found in documentation.
You may define g(x) as a stand-alone function and plug it into another function:
g = @(x) x^2+x;
y = @(x) 5 * g(x) + 1;
y(1)
>> 11
The function handle y can now be used as function to be optimized if parameters have been set accordingly.
y = @(x,xdata) x(1).*g(xdata)+x(2)+x(3).*xdata+x(4)*xdata.^2;
Kind regards,
Robert
