Re: [Rd] printing of complex numbers in R-alpha

From: Robin Hankin <r.hankin_at_noc.soton.ac.uk>
Date: Thu 21 Sep 2006 - 13:46:34 GMT

Hello

got it:

     o	The printing of complex numbers has changed, handling numbers
	as a whole rather than in two parts.  So both real and
	imaginary parts are shown to the same accuracy, with the
	'digits' parameter referring to the accuracy of the larger
	component, and both components are shown in fixed or
	scientific notation (unless one is entirely zero when it is
	always shown in fixed notation).

[this from the NEWS of R-2.2.0]

I'm struggling to reconcile the final clause of this with:

 > 1e100 + 1i
[1] 1e+100+1i
 > 1e100 + 1e-100i
[1] 1e+100+0i

in both of these cases, the real component is shown in scientific notation and the imaginary component isn't.

I'm finding the following example confusing too:

 > 1e100 + pi*1i*10^(c(-100,0,1,40,100)) [1] 1e+100+3.1416e-100i 1e+100+ 3.1416e+00i 1e+100+ 3.1416e+01i [4] 1e+100+ 3.1416e+40i 1e+100+3.1416e+100i  >

rksh

On 21 Sep 2006, at 14:11, Prof Brian Ripley wrote:

> On Thu, 21 Sep 2006, Martin Maechler wrote:
>
>>>>>>> "Robin" == Robin Hankin <r.hankin@noc.soton.ac.uk>
>>>>>>> on Thu, 21 Sep 2006 08:05:24 +0100 writes:
>>
>> Robin> Hello everyone
>> Robin> I am finding complex numbers to be printed oddly in R-
>> alpha.
>>
>>
>>>> 1e100+1e100i
>> Robin> [1] 1e+100+1e+100i
>>>> 1e100 + 1e44i
>> Robin> [1] 1e+100+100000000000000008821361405306422640701865984i
>>>> dput(1e100+1e44i)
>> Robin> 1e+100+100000000000000008821361405306422640701865984i
>>>>
>>
>> ouch, ouch!
>>
>> Robin> [same thing at home on a linux box]
>>
>>
>> Robin> The first line is what I would expect, the second and
>> third lines
>> Robin> aren't:
>> Robin> I would prefer "1e100+1e44i". Is this possible for
>> R-2.4.0?
>>
>> It should.
>
> I think the right answer is 1e100+0i: read what 'digits' means for
> complex
> numbers.
>
> It's been there since 2.2.0.
>
> --
> Brian D. Ripley, ripley@stats.ox.ac.uk
> Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
> University of Oxford, Tel: +44 1865 272861 (self)
> 1 South Parks Road, +44 1865 272866 (PA)
> Oxford OX1 3TG, UK Fax: +44 1865 272595
>
> ______________________________________________
> R-devel@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

--
Robin Hankin
Uncertainty Analyst
National Oceanography Centre, Southampton
European Way, Southampton SO14 3ZH, UK
  tel  023-8059-7743

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