Matlab, inserting the value of a vector in 3d matrix

Question

I have a 3D matrix a and a vector a1 . The size of a1 changes for each iteration. Now I want to input this vector into a certain position in a whose 2nd and 3rd column is defined. Something like this,

a(:,3,4)=a1;

But it gets the error "Assignment has more non-singleton rhs dimensions than non-singleton subscripts" . How can i solve it?

Answer 1

If the size of a1 changes at each iteration, you will need to preallocate a to the maximum size and use explicit subscripts for assignation

a = zeros(5,5,5)
a(1:length(a1),3,4)=a1;

Alternatively you can use a cell-array:

a{3,4} = a1

The cell array will be able to store vectors of different lengths.