[PYTHON MATRIX-SIG] Release 0.20 of matrix object is available

Paul. Dubois dubois1@llnl.gov
Fri, 08 Dec 1995 16:05:54 -0800


A followup to the remarks about precision.
In fact, Fortran 90 goes to considerable lengths to try to improve this
situation but it isn't REAL*8 that is the solution. Fortran 90 uses
something called a Kind specifier, and Kind specifiers are calculable
from desired characteristics at compile time. Actually knowing that
something is a certain number of bits doesn't tell you what you need to
know, as there is a tradeoff between precision and dynamic range. 
Anyway, you end up saying REAL(kind) x, y, z.

I believe Jim has made fundamentally the right decision in deciding that
the abstraction he is after is "things that store a homogenous bunch of
stuff in contiguous memory". This would be a parameterized type in other
languages, such as Eiffel's ARRAY[T], where one actually instantiates
ARRAY[DOUBLE], ARRAY[INTEGER], ARRAY[CHARACTER], ARRAY[TELEPHONE_BOOK],
etc. Since a large use of this abstraction is connection to C and
Fortran libraries, one has to be precise about it in a cross-language
way and I think the present proposal is correct. The question of what
language must be used to express this at the Python level is an
interesting one. While I favor names like IntegerMatrix, ..., reserving
Matrix to be a "smart" operator that decides on the type from the
arguments, there is a place for a version with a calculable type or type
code, so that one can get different things on different platforms with
the same source by doing tests on the system type.

I think Array is a better name than Matrix and if 'array' weren't
already taken would have no hesitation in going ahead. If we picked
Array as the name that is now Matrix, what would we call that which is
now 'matrix'? ArrayFromSequence ?

-- 
Paul F. Dubois, L-472				(510)-422-5426
Lawrence Livermore National Laboratory		FAX (510)-423-9969
Livermore, CA 94550				dubois1@llnl.gov
Consulting: PaulDubois@aol.com

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