CODEWITHSUNDEEP
matlabcurve-fitting
Linawck
Linawck

Reputation: 1

Matlab Curve Fitting without Toolbox

I am trying to find a fitting curve as described below. MATLAB's polyfit does not work in my case.
Known parameters: x and y, and the fitting curve y_fit = a * (x_fit) .^ n
(here, n may not be an integer).
I need to find a and n.

Upvotes: 0

Views: 862

Answers (1)

groovingandi
groovingandi

Reputation: 2016

Take the logarithm of both sides and use polyfit or just a plain x = A\b approach.

y_fit = a*(x_fit).^n

log(y_fit) = log(a) + n*log(x_fit)

If x_fit and y_fit are column vectors of data:

A = [ones(length(x_fit), 1), log(x_fit)];
b = log(y_fit);
x = A\b;
n = x(2)
a = exp(x(1))

Upvotes: 2

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