[PYTHON MATRIX-SIG] linear algebra (Column major arrays)

Phil Austin phil@geog.ubc.ca
Mon, 19 Aug 1996 12:54:50 -0700 (PDT)

>>>>> "Konrad" == Konrad HINSEN <hinsenk@ere.umontreal.ca> writes:

    >> Just to throw in a suggestion let me tell what the Ada95
    >> standard does to work around this problem. In Ada95 the
    >> compiler has to have a " pragma Convention (Fortran,
    >> Fortran_Matrix);" which changes the way an array is actually
    >> stored in memory.  For the programmer there is no change at
    >> all, the compiler takes care of all necessary changes to make
    >> the array Fortran as well as Ada compatible.
    >> Would this be possible in python without a serious perfomance
    >> overhead ?

    Konrad> One could have a second kind of array object that used
    Konrad> Fortran conventions for storage and inverts indexing. But
    Konrad> I doubt that this is worth the effort.

We're hoping that users can implement column-major arrays without
large performance penalties if they aren't intrinsic to the Python
matrix library.  Settling on one index order among our binary data api
(netcdf), other matrix packages (splus), and our compiled code (F77,
HPF, F90, and C++ using MV++,r A++/P++ or Barton and Nackman--all
column major), eliminates a vexing source of confusion and cuts a
suprising amount of work from debugging, tutorial writing, etc.

Phil Austin		INTERNET: phil@geog.ubc.ca
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