Transforming vector into triangular matrix

Hi guys,

I've got a 48x1 vector say [x1; x2; x3; x4;...x48]

I want to transform this into a 48x48 matrix that looks like:

x1 0 0 0 ...

x1 x2 0 0 ...

x1 x2 x3 0 ...

x1 x2 x3 x4 ...

....

What are some of the ways to do this? I know I could use diag() but that would only get me 1 diagonal line. Or should I try and use tril()? Thanks!

Answer 1

[Amit]

Lets call it A Then

A_new = repmat(A,1,48);
A_new = tril(A);

[Jeff]

Perfect, thank you!