Hi Bob,
The function FIT returns a cfit object for curves or a sfit object for surfaces. You can learn more about the objects in the documentation:
1. CFIT Object: http://www.mathworks.com/help/curvefit/cfit.html 2. SFIT object: http://www.mathworks.com/help/curvefit/sfit.html
In short, the CFIT object will return the model formula and the coefficients. For example,
>> load census;
>> f=fit(cdate,pop,'poly2')
f =
Linear model Poly2:
f(x) = p1*x^2 + p2*x + p3
Coefficients (with 95% confidence bounds):
p1 = 0.006541 (0.006124, 0.006958)
p2 = -23.51 (-25.09, -21.93)
p3 = 2.113e+04 (1.964e+04, 2.262e+04)
I assume from your question that you want to extract the coefficients into an array. You can do that by using the following syntax:
>> coeff = coeffvalues(f)
coeff =
1.0e+04 *
0.0000 -0.0024 2.1130
You will need use the COEFFVALUES function, details of which you can find in the following link: http://www.mathworks.com/help/curvefit/coeffvalues.html
If you also need to extract the formula and the coefficient names then you may use the following functions:
>> formula(f)
ans =
p1*x^2 + p2*x + p3
>> coeffnames(f)
ans =
'p1'
'p2'
'p3'
