How to do an interpolation with more than one variables? " Error using matlab.int​ernal.math​.interp1 Sample points must be unique."

Hello! I have a file with information (image 1). In matlab, I chose that file, read it and save the different columns as I want (image 2).

On data(:,1) which is my Phi angle I have values 0:5:360 and on data(:,2) which is my Theta angle I have values 0:5:180. In the file it looks like this:

0 0

0 5

0 10

0 15

... ...

0 180

5 0

5 5

5 10

... ...

5 180

... ...

360 0

360 5

... ...

360 180

So each combination of Phi and Theta have different values of E_phi and E_theta, which are the other columns.

My goal now is to do an interpolation to have, for example, the values of E_phi and E_theta for Phi = 0.6 and Theta = 1.2. For that I created the new arrays of Phi and Theta, called Phi_new and Theta_new, respectly. (You can see the code and results in images 3 and 4. I think it is correct, it is just for you to understand better).

So now I was doind this:

>> E_phi_new = interp1(Phi, E_phi, Phi_new, 'spline');

>> E_theta_new = interp1(Theta, E_theta, Theta_new, 'spline');

I discover that this is not possible because "Error using matlab.internal.math.interp1. Sample points must be unique." which makes sense. To do this I think I need both the variable Phi and Theta and not just one in each line. But I don't understand how to do it.

Have you got any suggestion? I am sorry for this big text, it is just to try to explain better my problem. In image 5 is the entire code, if it helps.

Thank you very much!

[Walter Roberson]

reshape() the data into a 2d array, and use interp2