error:
[theta, obj_value, conv, iters] = nls_estimate(theta, data, model, modelargs, control, nslaves)
inputs:
theta: column vector of model parameters
data: data matrix
model: name of function that computes the vector of sums of squared errors
modelargs: (cell) additional inputs needed by model. May be empty ('')
control: (optional) BFGS or SA controls (see bfgsmin and samin). May be empty ('').
nslaves: (optional) number of slaves if executed in parallel (requires MPITB)
outputs:
theta: NLS estimated value of parameters
obj_value: the value of the sum of squared errors at NLS estimate
conv: return code from bfgsmin (1 means success, see bfgsmin for details)
iters: number of BFGS iteration used
please see nls_example.m for examples of how to use this