How to index array with an array?

Hi I want to index an element in an array. The array u can be 1D, 2D or 3D, and I have an index id which is 1D, 2D or 3D. I'm currently doing:

u(id) = val;

This works fine in the 1D case. However, for 2D cases, where id = [row,column], this line doesn't set the 2D array correctly. For example:

u = [0 0 0;
     0 0 0;
     0 0 0];

% Access element at row 2, column 1
id = [2,1]
u(id) = 1; % Not always setting the desired element

Similarly in 3D, id = [widthId, heightId, depthId].

Is there a way to solve this?

Thank you very much!

[James Tursa]

Please give a small numerical example of exactly how your 2D and 3D indexes are stored.

Answer 1

[Stephen23]

u = [11,12,13;21,22,23;31,32,33]

u = 3×3

11 12 13 21 22 23 31 32 33

% Access element at row 2, column 1
id = [2,1]

id = 1×2

2 1

ic = num2cell(id);
u(ic{:})

ans = 21

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

https://www.mathworks.com/matlabcentral/answers/320713-how-to-operate-on-comma-separated-lists

[xiaojuezi]

Thank you very much!!