reindex

adds dimensions to make x look like y

Description

reindex(x,y) adds dimensions without the confusion of reshape. It makes x look like y. For example:
x = ones([1 5]);
y = ones([6 5 9]);
z = y + x; %this fails
z = y + reindex(x,y); %but this does not

Works for arbitrary dimensions, as long as all non-singleton dimensions of x are also dimension of y.

reindex is more general than bsxfun (though maybe slower), because it can do repmat and permute without much thought from user:
x = zeros([5 9]);
y = ones([3 5 1 9 2]);
z = bsxfun(@minus,y,x)); %fails because dimensions don't match
z = y-reindex(x,y); %works, z has dimension of y

• MATLAB release: MATLAB 7.3 (R2006b)

[John D'Errico]

Yes, but if you use bsxfun, you gain far more! By using bsxfun, you never need to expand these arrays at all. This becomes far more efficient, both in terms of memory and speed. Finally, bsxfun comes with matlab now, so you don't even need to download anything at all.