2D data fitting using fit and fittype

Hello everyone,

I have a 60x60 2D data set which I want to fit using the fit and fittype function, according to fitobject = fit([x,y],z,fitType).

my arrays are:

x = [1:60]

y = [1:60]

and z is a 60x60 array.

(When I use theese arrays in the curve fitting App it works perfectly fine for fittype: 'poly33'.)

I use the fit function as follows:

Fit_Background = fit([x',y],z,'poly33');

For that I get the following error:

Error using horzcat

Dimensions of arrays being concatenated are not consistent.

What am I doing wrong?

Answer 1

[Abhishek Gupta]

Hi,

As per my understanding, you are getting an error while fitting the data in x, y, and z. Note that the x, y, z are the column vectors of the same dimension in the 'fit' function. In your case, you can do the same as follows: -

x = [1:60]';    % column vector
y = [1:60]';    % column vector
X = repmat(x,60,1);    % get x for all values of z
Y = repelem(y,60);      % get y for all values of z
z = rand(60,60);        % replace this z with your 60x60 array
Z = z(:);       % make z a column vector

Fit_Background = fit([X,Y],Z,'poly33');     % fit

For more information, check out the documentation link below: -

https://www.mathworks.com/help/curvefit/fit.html