How to extend an array to a new dimension?

Suppose, I have an array

  a=rand(3, 4);

I want to create a new array 'b' which has [ 3, 4, 5] size, and all 2D matrix along the third dimension are equal to 'a'.

b = zeros([size(a) 5]);
for i=1:5
b(:, :, i) = a;
end

How can I do this using MATLAB functions.

Answer 1

[Star Strider]

One option is the repmat function —

  a=rand(3, 4);
  
  b = zeros([size(a) 5]);
for i=1:5
    b(:, :, i) = a;
end

b

b = 
b(:,:,1) =

    0.2207    0.2683    0.7580    0.4175
    0.6446    0.7519    0.0339    0.4267
    0.9818    0.8499    0.6944    0.9327


b(:,:,2) =

    0.2207    0.2683    0.7580    0.4175
    0.6446    0.7519    0.0339    0.4267
    0.9818    0.8499    0.6944    0.9327


b(:,:,3) =

    0.2207    0.2683    0.7580    0.4175
    0.6446    0.7519    0.0339    0.4267
    0.9818    0.8499    0.6944    0.9327


b(:,:,4) =

    0.2207    0.2683    0.7580    0.4175
    0.6446    0.7519    0.0339    0.4267
    0.9818    0.8499    0.6944    0.9327


b(:,:,5) =

    0.2207    0.2683    0.7580    0.4175
    0.6446    0.7519    0.0339    0.4267
    0.9818    0.8499    0.6944    0.9327

b2 = repmat(a, 1, 1, 5)

b2 = 
b2(:,:,1) =

    0.2207    0.2683    0.7580    0.4175
    0.6446    0.7519    0.0339    0.4267
    0.9818    0.8499    0.6944    0.9327


b2(:,:,2) =

    0.2207    0.2683    0.7580    0.4175
    0.6446    0.7519    0.0339    0.4267
    0.9818    0.8499    0.6944    0.9327


b2(:,:,3) =

    0.2207    0.2683    0.7580    0.4175
    0.6446    0.7519    0.0339    0.4267
    0.9818    0.8499    0.6944    0.9327


b2(:,:,4) =

    0.2207    0.2683    0.7580    0.4175
    0.6446    0.7519    0.0339    0.4267
    0.9818    0.8499    0.6944    0.9327


b2(:,:,5) =

    0.2207    0.2683    0.7580    0.4175
    0.6446    0.7519    0.0339    0.4267
    0.9818    0.8499    0.6944    0.9327

Both results are the same.

.