# [PYTHON MATRIX-SIG] IEEE exceptions, casting, matrix multiplies, and default types

**James Hugunin
**
jjh@mama-bear.lcs.mit.edu

*Fri, 3 Nov 95 10:37:02 -0500*

I'd like to generalize this discussion a little bit. I've noticed four
areas where the easiest solution would be to add a user-settable global
variable to indicate a "desired" mode, yet I agree with Guido that as a
general rule this is an extremely bad idea.
1) 1/0. returns Inf or raises exception
[Note: Matrix_i creates a matrix of ints, Matrix_d creates one of doubles]
2) Matrix_i(1,2,3) * Matrix_d(1.,2.,3.) == Matrix_d(1.,4.,6.) or raises exception
3) a * b is element-wise or is linear algebra style multiply
4) add([1,2,3], [4,5,6]) == Matrix_?(5,7,9) where the question is what the
? should be.
I'm busy this morning getting the 0.11 release of the matrixobject
together, so I don't have time for much more comment, I just wanted to point
out that this is a very general question (in particular when thinking about
matrices), and if we're really lucky there might be a nice general purpose
answer.
-Jim
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