Here is an easy way to do it in 3D for this vector:
v = [6;15;24];
repmat(v, [1 3 3])/9
A generalized solution that will unproject any vector into a shape with your requiredDimensions
:
v = [6;15;24];
requiredDimensions = 3;
n = numel(v);
myDims = [1 repmat(n,1,requiredDimensions - 1)];
repmat(v, myDims )/prod(myDims)