how to solve triangular systems

[Federico Poloni]

Hi everyone,
 sorry to bother this mailing list but I don't seem to find this
anywhere in the docs.
about operators \ and / :
When the system matrix is diagonal or triangular does Octave solve it in
"the smart way" (using O(n) and O(n^2) flops respectively)? Which other
structures are recognized and supported by these operators (for example,
matlab says it recognizes permuted-triangular systems)?

If the answer to the first question is no, then:
Has Octave a "standard" way to solve triangular systems, or does one
have to write back-substitution from scratch every time?

Thanks in advance,
--federico poloni