On Tue, Mar 18, 2014 at 12:16 AM, Christophe Bal <projetmbc@gmail.com> wrote:

> I think that weak-left is a little strange, just think > a little of the operators used by mathematicians that > always follow a hierarchy.

Not sure what you mean -- I don't think most mathematicians think that scalar and matrix multiplication are above or below each other in precedence, for example.

You're right but on the other hand, I've never seen mixed use of matrix and scalar products without parenthesis... Indeed in math, we can use < Au , Bv

for the scalar product of two matrix-vector products.

Not scalar product, scalar multiplication -- you're saying (I think) that 3 * Matrix1 * Matrix2 is just like 3 * Matrix1 + Matrix2 in the sense that mathematicians think of the 3 * Matrix1 part is very different from, and higher precedence than, the Matrix1 + Matrix2 part. And similarly that Matrix1 * Matrix2 * 3 is just like Matrix1 + Matrix2 * 3 But in fact I think if you asked most mathematicians which of the "*"'s in Matrix1 * Matrix2 * 3 is higher precedence, they would think this question very odd! -n -- Nathaniel J. Smith Postdoctoral researcher - Informatics - University of Edinburgh http://vorpus.org