User`s guide

Parametric Fitting
3-25
• TolFun — Termination tolerance used on stopping conditions involving the
function (model) value. The default value is 10
-6
.
•
TolX — Termination tolerance used on stopping conditions involving the
coefficients. The default value is 10
-6
.
Coefficient Parameters
• Unknowns — Symbols for the unknown coefficients to be fitted.
•
StartPoint — The coefficient starting values. The default values depend on
the model. For rational, Weibull, and custom models, default values are
randomly selected within the range [0,1]. For all other nonlinear library
models, the starting values depend on the data set and are calculated
heuristically.
•
Lower — Lower bounds on the fitted coefficients. The bounds are used only
with the trust region fitting algorithm. The default lower bounds for most
library models are
-Inf, which indicates that the coefficients are
unconstrained. However, a few models have finite default lower bounds. For
example, Gaussians have the width parameter constrained so that it cannot
be less than 0.
•
Upper — Upper bounds on the fitted coefficients. The bounds are used only
with the trust region fitting algorithm. The default upper bounds for all
library models are
Inf, which indicates that the coefficients are
unconstrained.
For more information about these fit options, refer to “Optimization Options
Parameters” in the Optimization Toolbox documentation.