From bbolker at gmail.com  Mon Jul 14 17:14:30 2014
From: bbolker at gmail.com (Ben Bolker)
Date: Mon, 14 Jul 2014 15:14:30 +0000
Subject: [Rd] cummax / cummin for complex numbers
References: <9591F061-56E7-4FA6-9A84-AED2C3B56F32@oracle.com>
Message-ID: <loom.20140714T170807-611@post.gmane.org>

Michael Haupt <michael.haupt <at> oracle.com> writes:

> 
> Dear all,
> 
> in R 3.1.0, this is happening:
> 
> > cummin(c(1+1i,2-3i,4+5i))
> Error in cummin(c(1 + (0+1i), 2 - (0+3i), 4 + (0+5i))) : 
>   'cummax' not defined for complex numbers
> > cummax(c(1+1i,2-3i,4+5i))
> Error in cummax(c(1 + (0+1i), 2 - (0+3i), 4 + (0+5i))) : 
>   'cummin' not defined for complex numbers
> 
> It may be fixed in R-devel, but I thought I'd mention it to make sure ...
> 
> Best,
> 
> Michael

  Well, it is documented in the development version:

   x: a numeric or complex (not ?cummin? or ?cummax?) object, or an
          object that can be coerced to one of these.

I imagine the problem is in coming up with a good, consistent definition
of the min/max for complex numbers: would you prefer min/max modulus,
phase, real part, imaginary part ... ? max()/min() aren't even defined
for complex numbers in R ...



[Rd] cummax / cummin for complex numbers
Ben Bolker