Determine if cfit, sfit, or
fittype object is linear
flag = islinear(fun)
flag = islinear(fun) returns a flag of
1 if the cfit, sfit, or
fittype object fun represents a linear
model, and a flag of 0 if it does not.
islinear assumes that all custom models specified by the
fittype function using the
syntax ftype = fittype('expr') are nonlinear models. To
create a linear model with fittype that will be recognized as
linear by islinear (and, importantly, by the algorithms of
fit), use the syntax
ftype = fittype({'expr1','expr2',...,'exprn'}).
f = fittype('a*x+b')
f =
General model:
f(a,b,x) = a*x+b
g = fittype({'x','1'})
g =
Linear model:
g(a,b,x) = a*x + b
h = fittype('poly1')
h =
Linear model Poly1:
h(p1,p2,x) = p1*x + p2
islinear(f)
ans =
0
islinear(g)
ans =
1
islinear(h)
ans =
1