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<H2><A NAME="SECTION04532000000000000000">Checking the BLAS and BLACS Libraries</A></H2>
<A NAME="subsecblasblacs"> </A>
<P>
The best way to determine whether one is using efficient BLAS and BLACS
libraries is to time them. ScaLAPACK provides a rudimentary
BLAS and BLACS timer in the examples/timers directory on <EM>netlib</EM>
and on the CD-ROM. This directory also contains pointers and
instructions for
more complete timers, such as the LAPACK BLAS timer and the
message-passing benchmark program [<A HREF="node189.html#dunigan96a">46</A>]. We encourage users
to use these timers to measure the performance of the BLAS.
<P>
This ScaLAPACK examples/timers directory also contains pointers to some
benchmark results and some pointers on interpreting the results
of the timers.
<P>
To determine which BLAS and BLACS libraries are being linked in,
users should check the output of the linker. If the <TT>Makefile</TT> includes
<TT>SLmake.inc</TT>,
the BLAS library is given by the macro BLASLIB in <TT>SLmake.inc</TT> while
the BLACS library is given by the macro BLACSLIB. If the BLAS library
name is of the form <TT>blas_LINUX.a</TT>, this is probably the (slow)
reference implementation BLAS. If the
BLAS library name is <TT>-lblas</TT>, <TT>-lessl</TT>, <TT>-ldxml</TT> or
the like, this may be an optimized BLAS library.
<P>
<BR> <HR>
<P><ADDRESS>
<I>Susan Blackford <BR>
Tue May 13 09:21:01 EDT 1997</I>
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