On Sat, 2005-07-23 at 12:06 -0700, Robert Kern wrote:
Soeren Sonnenburg wrote:
Dear all,
I am new to numarray and as I am trying to use it day-by-day I am now wondering about certain numeric/numarray design issues. Please forgive me / correct me as I probably misunderstood certain issues.
-- Why did you choose row-major instead of column major format as practiced by R/octave/matlab... Doesn't that mean performance problems as fortran/blas is optimized if you work with the transposed version ?
Not everyone is interfacing with optimized FORTRAN code. Those who are are usually using ATLAS as their BLAS, and ATLAS has row-major versions of the BLAS subroutines. Row-major is C's convention and numarray/Numeric largely follow that. There are of course some performance issues when interfacing with FORTRAN code that expects column-major, but there would be other performance problems if numarray/Numeric were column-major and interfacing with row-major code.
Well but why did you change to the C version then ? Well maybe if it is about optimizing stuff seriously one could work with the transpose anyway...
Often, though, a "row" vector can also be used in place of a "column" vector. Although sometimes not:
You are right, thanks!
Are there more elegant ways to do this ? Which issues are likely to be fixed in the future ?
None. They're not broken, just different from what you are used to.
Thanks a lot for your very helpful mail! Do you know whether mixing slices and arrays will be supported at some point a[:,[0,1]] ? Soeren.