Re: [R] bug?

[Spencer Graves]

	  This may be picking nits, but from "%~=%" as written, I think I would 
get 1e-50 %~=% 5e-50.  With numbers ranging from 1e-51 to 1e-48, this is 
rarely what I would want.  Change "-" to "+" in the above example, and I 
get the same result.

	  Something like the following might be more appropriate:

"%~=%"<-function(x,y){
        if(is.numeric(x) & is.numeric(y)){
           xpy <- (x+y)
           xpy[xpy==0] <- 4*.Machine$double.eps
           return((abs(x-y)/xpy)<(4*.Machine$double.eps))
         }
         else return(x==y)
}
	  This is close but not quite there yet, I don't think.  Consider the 
following:

> 1e-50 %~=% 2e-50
[1] FALSE
> 0 %~=% 2e-50
[1] FALSE
> 1e+50 %~=% 2e+50
[1] FALSE
> 0 %~=% 2e+50
[1] FALSE
> 11e-50 %~=% 2e-50
[1] FALSE
> 1 %~=% (1+.Machine$double.eps)
[1] TRUE
> 1 %~=% (1+3*.Machine$double.eps)
[1] TRUE
?????? spencer graves

(Ted Harding) wrote:
At 7/14/2003 at 03:29 AM, Marc Vandemeulebroecke wrote:
Dear R programmers,
is there a sensible explanation for the following behaviour?


seq(0.7, 0.9, by=0.1) == 0.8
[1] FALSE FALSE FALSE


Yet another %**% function ...


"%~=%"<-function(x,y){abs(x-y)<1e-15}
seq(0.7, 0.9, by=0.1) %~=% 0.8
[1] FALSE  TRUE FALSE

Ted.

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Date: 14-Jul-03                                       Time: 22:16:38
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