How can I create a triangular matrix based on a vector, in MATLAB?

Question

Let\'s say I\'ve got a vector like this one:

A = [101:105]

Which is really:

[ 101, 102, 103, 104, 105 ]

And I

Answer 1

The best solutions are listed by Loren. It's also possible to create these matrices using SPDIAGS:

vec = 101:105;
A = full(spdiags(repmat(vec,5,1),0:4,5,5));  % The second matrix
B = fliplr(full(spdiags(repmat(fliplr(vec),5,1),0:4,5,5)));  % The first matrix

I recall creating banded matrices like this before I found out about some of the built-in functions Loren mentioned. It's not nearly as simple and clean as using those, but it worked. =)