[Numpy-discussion] Array vectorization in numpy

[Nadav Horesh]

For such expressions you should try numexpr package: It allows the same type of optimisation as Matlab does:  run a single loop over the matrix elements instead of repetitive loops and intermediate objects creation.

  Nadav

> Besides the matlab/numpy comparison, I think that there is an inherent problem with how expressions are handled, in terms of efficiency.
> For instance, k = (m - 0.5)*0.3 takes 52msec average here (2000x2000 array), while k = (m - 0.5)*0.3*0.2 takes 0.079, and k = (m - 0.5)*0.3*0.2*0.1 > takes 101msec.
> Placing parentheses around the scalar multipliers shows that it seems to have to do with how expressions are handled, is there sometihng that can >be done about this so that numpy can deal with expressions rather than single operations chained by python itself? Maybe I am missing the point as well.

----------------------
Carlos Becker