According to the information shared, you currently have 3D gridded data and data at each grid point. You are further trying to interpolate the data at each point along the z-axis with a value of 2.5. This can be done by using interp3 function in the following way.
% Given data
a = [0.25, 0.5, 0.75];
b = [0.25, 0.5, 0.75];
c = [1, 2, 3];
[A, B, C] = meshgrid(a, b, c);
Arr = [1 2 3; 4 5 6;7 8 9];
Arr(:, :, 2) = [10 11 12; 13 14 15;16 17 18];
Arr(:, :, 3) = [15 16 17; 18 19 20; 21 22 23];
% Interpolate along the C axis at 2.5
interp_value = 2.5;
Now you need to query coordinates matching the size of A, B, and C in the following way.
[Xq, Yq, Zq] = meshgrid(a, b, interp_value);
Now after obtaining the meshgrid along different axis and query coordinates with the new interpolated mesh grid information, we can interpolate the available data at each grid point using interp3 function like,
interpolated_result = interp3(A, B, C, Arr, Xq, Yq, Zq);
disp(interpolated_result);
You can find more information about interp3 function from below given resources. Thanks.
