[Rd] cummax / cummin for complex numbers
bbolker at gmail.com
Mon Jul 14 17:14:30 CEST 2014
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 ...
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 ...
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