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islinear

Determine if cfit, sfit, or fittype object is linear

Syntax

flag = islinear(fun)

Description

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.

Note

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'}).

Examples

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

See Also

Introduced in R2006b