If a bottleneck contains vector and/or matrix operations,
you may be able to improve program performance by specifying the
+Ovectorize option.
See “Optimizing Your Program” for details.
Alternatively, you may be able to replace the operations with
calls to the BLAS library, libblas
(provided with the HP Fortran 90 and HP FORTRAN/9000 products only).
The libblas
and +Ovectorize
calls are faster than code loops that you can write yourself because
they take into account alignment, data cache, and other machine-dependent
characteristics. Not all matrices, however, are good candidates
for libblas calls
or for +Ovectorize.
If the array contains fewer than about twenty elements, the overhead
incurred by making the calls may offset the increased performance
yielded by these routines.
For more information about the libblas
routines, see “The BLAS Library (libblas)”,
the HP Fortran 90 Programmer's Reference,
and the HP FORTRAN/9000 Programmer's Reference.
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