Hello everyone
On 1 Sep 2007, at 01:39, Duncan Murdoch wrote:
> The IEEE floating point standard allows for negative zero, but it's
> hard
> to know that you have one in R. One reliable test is to take the
> reciprocal. For example,
>
>> y <- 0
>> 1/y
> [1] Inf
>> y <- -y
>> 1/y
> [1] -Inf
On Sat, Sep 01, 2007 at 05:22:26PM -0600, Tony Plate wrote:
> One place where I've been caught by -ve zeros is with unit tests. If
> identical(-0, 0) returns FALSE, and the object storage doesn't preserve
> -ve zeros, that can lead to test failures that are tricky to debug.
>
> However, it does
One place where I've been caught by -ve zeros is with unit tests. If
identical(-0, 0) returns FALSE, and the object storage doesn't preserve
-ve zeros, that can lead to test failures that are tricky to debug.
However, it doesn't look like that is too much a problem in the current
incarnation o
On Fri, Aug 31, 2007 at 08:39:02PM -0400, Duncan Murdoch wrote:
[snip]
> The other day I came across one in complex numbers, and it took me a
> while to figure out that negative zero was what was happening:
>
> > x <- complex(real = -1)
> > x
> [1] -1+0i
> > 1/x
> [1] -1+0i
> > x^(1/3)
>
[EMAIL PROTECTED] wrote:
>
> On 8/31/07, Duncan Murdoch <[EMAIL PROTECTED]> wrote:
>> The IEEE floating point standard allows for negative zero, but it's hard
>> to know that you have one in R. One reliable test is to take the
>> reciprocal. For example,
>>
>> > y <- 0
>> > 1/y
>> [1] Inf
>>
On 8/31/07, Duncan Murdoch <[EMAIL PROTECTED]> wrote:
> The IEEE floating point standard allows for negative zero, but it's hard
> to know that you have one in R. One reliable test is to take the
> reciprocal. For example,
>
> > y <- 0
> > 1/y
> [1] Inf
> > y <- -y
> > 1/y
> [1] -Inf
>
>
day27
svn rev42083
language R
version.string R version 2.5.1 (2007-06-27)
Steven McKinney
-Original Message-----
From: [EMAIL PROTECTED] on behalf of Duncan Murdoch
Sent:
On 8/31/07, Duncan Murdoch <[EMAIL PROTECTED]> wrote:
> The IEEE floating point standard allows for negative zero, but it's hard
> to know that you have one in R. One reliable test is to take the
> reciprocal. For example,
>
> > y <- 0
> > 1/y
> [1] Inf
> > y <- -y
> > 1/y
> [1] -Inf
>
> The
The IEEE floating point standard allows for negative zero, but it's hard
to know that you have one in R. One reliable test is to take the
reciprocal. For example,
> y <- 0
> 1/y
[1] Inf
> y <- -y
> 1/y
[1] -Inf
The other day I came across one in complex numbers, and it took me a
while to
