>> [1] TRUE
>>>
>>
>> Perhaps the moral of the story is that one should
>> exercise caution and keep
>> track of significant digits.
>>
>> -- TMK --
>> 212-460-5430 home
>> 917-656-5351 cell
>>
>>
>>
>>> From: &qu
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> On Behalf Of Talbot Katz
> Sent: Monday, July 30, 2007 10:55 AM
> To: [EMAIL PROTECTED]
> Cc: [EMAIL PROTECTED]; r-help@stat.math.ethz.ch
> Subject: Re: [R] Matrix Multiplication, Floating-Point
-- TMK --
> 212-460-5430 home
> 917-656-5351 cell
>
>
>
> >From: "Charles C. Berry" <[EMAIL PROTECTED]>
> >To: Talbot Katz <[EMAIL PROTECTED]>
> >CC: r-help@stat.math.ethz.ch
> >Subject: Re: [R] Matrix Multiplication,
> Floati
that one should exercise caution and keep
> track of significant digits.
>
> -- TMK --
> 212-460-5430 home
> 917-656-5351 cell
>
>
>
> >From: "Charles C. Berry" <[EMAIL PROTECTED]>
> >To: Talbot Katz <[EMAIL PROTECTED]>
> >CC: r-hel
at.math.ethz.ch; Doran, Harold
> Subject: Re: [R] Matrix Multiplication, Floating-Point, etc.
>
> Thank you for responding!
>
> I realize that floating point operations are often inexact,
> and indeed, the difference between the two answers is within
> the all.equal tolerance
ot;Charles C. Berry" <[EMAIL PROTECTED]>
>To: Talbot Katz <[EMAIL PROTECTED]>
>CC: r-help@stat.math.ethz.ch
>Subject: Re: [R] Matrix Multiplication, Floating-Point, etc.
>Date: Mon, 30 Jul 2007 09:27:42 -0700
>
>
>
>7.31 Why doesn't R think these number
7.31 Why doesn't R think these numbers are equal?
On Fri, 27 Jul 2007, Talbot Katz wrote:
> Hi.
>
> I recently tried the following in R 2.5.1 on Windows XP:
>
>> ev2<-c(0.8,-0.6)
>> ev1<-c(0.6,0.8)
>> ev1%*%ev2
> [,1]
> [1,] -2.664427e-17
>> sum(ev1*ev2)
> [1] 0
>>
>
> (I got the s
Behalf Of Talbot Katz
> Sent: Friday, July 27, 2007 6:31 PM
> To: r-help@stat.math.ethz.ch
> Subject: [R] Matrix Multiplication, Floating-Point, etc.
>
> Hi.
>
> I recently tried the following in R 2.5.1 on Windows XP:
>
> >ev2<-c(0.8,-0.6)
> >ev1<
Hi.
I recently tried the following in R 2.5.1 on Windows XP:
>ev2<-c(0.8,-0.6)
>ev1<-c(0.6,0.8)
>ev1%*%ev2
[,1]
[1,] -2.664427e-17
>sum(ev1*ev2)
[1] 0
>
(I got the same result with R 2.4.1 on a different Windows XP machine.)
I expect this issue is very familiar and probably has be
