# [MATRIX-SIG] integer division -- what a concept!

**Carlos Maltzahn
**
carlosm@moet.cs.colorado.edu

*Fri, 16 Jan 1998 17:29:58 -0700 (MST)*

On Sat, 17 Jan 1998, Rupert Mazzucco wrote:
>* On Fri, 16 Jan 1998, Carlos Maltzahn wrote:
*>*
*>* > I disagree:
*>* >
*>* > Assuming n is an integer matrix. If you expect float results from matrix
*>* > operations you should have the matrices typed as float in the first
*>* > place. This would ensure that all operations result in floats.
*>*
*>* I'm afraid I don't quite get your point. If I write e.g.
*>*
*>* dphi = zeros(( max,), Complex )
*>* ...
*>* for n in xrange( 1, max ):
*>* dphi[n] = phi[n-1] - ( n / ( n+1 )) * phi[n]
*>* ^^^^^^^^^^^
*>* how would "typing my matrices as float in the first place" help?
*
It wouldn't. My point was that integer division can hurt you if you aren't
sure of the argument types of a division. In your example it is very
clear what n is: an integer loop variable. I would be very surprised if
the subexpression ( n / ( n+1 )) would result in a float since it
obviously only consists of integers. But that might be because I'm a
computer scientist and not a mathematician.
Carlos
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