MATLAB: How to fit a power law relationship in a scatter plot

Question

I have a scatter plot and I need to fit a power law line in the plot. It is very simple in excel but, I don't know why it is that hard in matlab! Any ideas please.

thanks

Answer 1

You have to write your own functions to fit your data in MATLAB, but that is not difficult.

Try this:

x = indpendent_variable;                                % Substitute A Vector

y = dependent_variable;                                 % Substitute A Vector
pwrlaw = (@b,x) b(1).*x.^b(2);                          % Objective Function
nrmrsd = @(b) norm(y - pwrlaw(b,x));                    % Cost Function
B = fminsearch(nrmrsd, [1; 1]);                         % Estimate Parameters
figure(1)
scatter(x, y)
hold on
plot(sort(x), pwrlaw(B,sort(x)))
hold off
grid