Re: [ublas] [BLAS bindings] help appreciated on using trmv and gbmv

Subject: Re: [ublas] [BLAS bindings] help appreciated on using trmv and gbmv
From: Florent Teichteil (florent.teichteil_at_[hidden])
Date: 2012-10-08 03:31:23

> you are aware that, by definition, upper and lower matrices do not have
> entries on the diagonal? In your test case, gemv takes those into
> account, but trmv will happily skip over them. That explains the
> difference in results.

Are you sure about this? I've never seen such a definition anywhere. 
Even the definition given by ublas does not state that has to be zero:

http://www.boost.org/doc/libs/1_51_0/libs/numeric/ublas/doc/triangular.htm

Wikipedia and mathworld say the same thing: the diagonal is included in 
a triangular matrix:

http://mathworld.wolfram.com/UpperTriangularMatrix.html
http://en.wikipedia.org/wiki/Triangular_matrix

Is it a restriction of blas?

Cheers
Florent