[Numpy-discussion] RE: default axis for numarray

Paul F Dubois paul at pfdubois.com
Tue Jun 11 13:57:03 CDT 2002


One can make a case for allowing == and != for complex arrays, but >
just doesn't make sense and should not be allowed.


> -----Original Message-----
> From: numpy-discussion-admin at lists.sourceforge.net 
> [mailto:numpy-discussion-admin at lists.sourceforge.net] On 
> Behalf Of Perry Greenfield
> Sent: Tuesday, June 11, 2002 11:52 AM
> To: eric jones; 'Konrad Hinsen'
> Cc: numpy-discussion at lists.sourceforge.net
> Subject: RE: [Numpy-discussion] RE: default axis for numarray
> 
> 
> <Eric Jones writes>:
>    <Konrad Hinsen writes>:
> 
> > > What needs to be improved in that area?
> > 
> > Comparisons of complex numbers.  But lets save that debate 
> for later.
> > 
>  
> No, no, let's do it now. ;-) We for one would like to know for 
> numarray what should be done.
> 
> If I might be presumptious enough to anticipate what Eric 
> would say, it is that complex comparisons should be allowed, 
> and that they use all the information in the complex number 
> (real and imaginary) so that they lead to consistent results 
> in sorting.
> 
> But the purist argues that comparisons for complex numbers 
> are meaningless. Well, yes, but there are cases in code where you 
> don't which such comparisons to cause an exception. But even 
> more important, there is at least one case which is 
> practical. It isn't all that uncommon to want to eliminate 
> duplicate values from arrays, and one would like to be able 
> to do that for 
> complex values as well. A common technique is to sort the 
> values and then eliminate all identical adjacent values. A 
> predictable comparison rule would allow that to be easily implemented.
> 
> Eric, am I missing anything in this? It should be obvious 
> that we agree with his position, but I am wondering if there 
> are any arguments we have not heard yet that outweigh the 
> advantages we see.
> 
> Perry
> 
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