[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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