Array indices must be positive integers or logical values.

hello,

Trying to plot but I'm having a indexing issue while using meshgrid. I needed theta to have the same dimensions as R_mesh and Z_mesh but when I meshgrid the theta variable I get the "Array indices must be positive integers or logical values." error on the function below.

Here is what I have:

 r = (0:1:500);
 z = (-250:1:50);
 theta = (0:.0209:2*pi);
 [R_mesh,Z_mesh]= meshgrid(r,z);
 [R_2,theta_mesh]= meshgrid(r,theta);

 % Z source
 z_s = -20; 

 % Wave length and number
 lamda = 2;
 k = 2*pi/lamda;

 % Spherical Wave convertion 
 R1 = sqrt(R_mesh.^(2)+(Z_mesh+z_s).^2);
 R  = R1 + z_s.*sin(theta_mesh);

 % Approxamate Lloyd Mirror Function to create plot
  Approx_Mirror_Func = 1./R((exp((1i*k.*(R-z_s.*sin(theta_mesh)))))-...
                            (exp((1i*k.*(R+z_s.*sin(theta_mesh))))));
 % Transmission Loss Factor
 TL_Approx = -10*log10(abs(Approx_Mirror_Func/1).^2);

 % Plot of the function 
 figure('Name','Question 1b','NumberTitle','off')
 pcolor(r,z,TL_Approx)

Any help would be appreciated. Thanks

[dpb]

You use the meshgrid values to generate the points at which the function is to be evaluated; then you plot the result of that evaluation.

Approx_Mirror_Func = 1./R((exp((1i*k.*(R-z_s.*sin(theta_mesh)))))-...
                          (exp((1i*k.*(R+z_s.*sin(theta_mesh))))));

It's not R((exp(...) which is using the expression as a subscript into the R array that you want above but R and some other mathematical function; I'm not sure just what but maybe simply ".*" to multiply by the exponential?

[Polo]

Adding the "*" to the the equation fixed the array issue. thanks.