Comment on "Java Numerics"

[James W. Demmel]

I read Jerome Coonen's recent contribution on "Java Numerics" with
great interest, because of related issues arising in the ScaLAPACK
numerical library project, which aspires to produce portable parallel
library code, and so must (conceivably) contend with a user who
connects a Cray C90, DEC Alpha, PowerPC and Pentium across a network
to cooperate in a computation. There are some such "heterogeneous
computations" that we understand how to do correctly, and others that
we do not. Some problems seem beyond our control to fix in any
cost effective way (such as an Ultrasparc sending a denormalized
number to a DEC Alpha, which then faults, and may deadlock the computation).
For a technical report discussing these and other issues, see LAPACK
Working Note 112, http://www.netlib.org/lapack/lawns.

Jim Demmel
UC Berkeley