Re: What to give as "real column vector of initial parameters" to nonlin_curvefit?

[Pavel Hofman]

Dne 11. 06. 20 v 14:50 Doron Behar napsal(a):
> 
> What am I supposed to give the 2nd argument? It seems like a necessary
> argument according to the signature. The docs don't explain much about
> it and I haven't found much in the mailing list's archives.

Initial values of the searched-for parameters to start with, typically
some estimate.

## initial values:
init = [.25; .25];  <------
## linear constraints, A.' * parametervector + B >= 0
A = [1; -1]; B = 0; # p(1) >= p(2);
settings = optimset ("inequc", {A, B});

## start optimization
[p, model_values, cvg, outp] = nonlin_curvefit (f, init, indep, obs, <--
  settings)

The definition says
Function File: [p, fy, cvg, outp] = nonlin_curvefit (f, pin, x, y)

where pin means p_initial or p_input
> 
> I tried to take the example and fiddle with the values they give there
> and I haven't noticed any change in the final plots of the data vs the
> fit...

That is because all your fitting runs converged from the different
initial values to the same optimal result. The best proof the method
works :-)

Best regards,

Pavel.