# [PYTHON MATRIX-SIG] Let's get going

**Hinsen Konrad
**
hinsenk@ere.umontreal.ca

*Wed, 13 Sep 1995 14:28:26 -0400*

> Why would it have to be copied whenever it is passed to a function?
> It would be sufficient to make a copy whenever the matrix is
> changed.
This gets back to my earlier comment that slices, as proposed cannot
be matrices because they store a reference to the data from which they
were created and a bunch of offsets for accessing the orinal data
properly. When passed to math/sci libraries, they'll have to be
converted to real matrices so that their data are contiguous.
I see. "Function" means "function in an external library", not
"Python function" as I had assumed.
BTW, there is a good book called "Scientific and Engineering C++"
that appeared recently, unfortunately I don't remember the names
of the authors (but I can check at home). It contains a
very good discussion of how a matrix class in C++ could be
designed, and this covers many of the topics we are discussing
here. Unfortunately they treat only one- and two-dimensional
matrices.
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Konrad Hinsen | E-Mail: hinsenk@ere.umontreal.ca
Departement de chimie | Tel.: +1-514-343-6111 ext. 3953
Universite de Montreal | Fax: +1-514-343-7586
C.P. 6128, succ. A | Deutsch/Esperanto/English/Nederlands/
Montreal (QC) H3C 3J7 | Francais (phase experimentale)
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