R devel - Jul 2014 - cummax / cummin for complex numbers

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

-- 
Dr. Michael Haupt
Principal Member of Technical Staff
Phone: +49 331 200 7277, Fax: +49 331 200 7561
Oracle Labs
Oracle Deutschland B.V. & Co. KG, Schiffbauergasse 14, 14467 Potsdam,
Germany

On Jul 14, 2014, at 9:53 AM, Michael Haupt <michael.haupt at oracle.com>
wrote:
> 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

The help file for cummax/cummin in 3.1.1 specifically states:

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


So why would you expect it to work for cummin or cummax when you pass a complex
'x'?

Regards,

Marc Schwartz

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 ...