Input argument names of cfit, sfit,
or fittype object
args = argnames(fun)
args = argnames(fun) returns the input argument (variable and
coefficient) names of the cfit, sfit, or
fittype object fun as an
n-by-1 cell array of character vectors
args, where n = numargs(fun).
f = fittype('a*x^2+b*exp(n*x)');
nargs = numargs(f)
nargs =
4
args = argnames(f)
args =
'a'
'b'
'n'
'x'