Curve fitting for degrees less than one

So, I was trying to curve fit stretch and strain curve for Mooney Rivlin model and I was just curious if it is at all possible to curve fit a variable for powers less than one? I want fit for x^2, x^1 ,x^-1 and x^-2. But the curve fitting toolbox wont let me manually choose the power. As soon as I set the degree to 4, the powers are 1,2,3 and 4 by default.

Answer 1

[Ameer Hamza]

You can choose any exponent you want. For example

x = linspace(1, 2);
y = 2*x.^0.5 + 4.1*x.^1.2 + 3.3;

ft = fit(x.', y.', 'a*x.^0.5 + b*x.^1.2 + c')

Are you using cftool? If yes, choose custom equation in the menu.

[KAMRAN EQUBAL]

Thankyou that was really helpful

[Ameer Hamza]

I am glad to be of help!