[R] Bug on MWC1019?

[Uwe Ligges]

Guido Montorsi wrote:

> Dear R-developer (Marsaglia??)
> 
> The following  piece of code from package SuppDist , routine "dist.cc" seems
> to have a bug

The package is called *SuppDists*.
Bug reports and contributions for contributed packages should be 
addressed to the package maintainer (CCing, he might not be listening) 
rather than to R-help. Thanks.

Uwe Ligges


> ULONG MWC1019(void){
> 	ULONG long t;
> 	int	i = endQ-1;
> 
> 	t = 147669672LL*Q[i] + Q[endQ];
> 	Q[endQ] = (t>>32);
> 	if(i>0)
> 		return(Q[i--] = t);
> 	i = endQ-1;
> 	return(Q[0] = t);
> }
> 
> in fact , being "i" a local variable that have automatic storage, it is
> initialized to endQ-1 (1019)
>  each time the routine is called so that it can never
> cycle through all values as it should.
> 
> I think it should be declared as static:
> 
> ULONG MWC1019(void){
> 	ULONG long t;
> 	static int	i = endQ-1;
> 
> 	t = 147669672LL*Q[i] + Q[endQ];
> 	Q[endQ] = (t>>32);
> 	if(i>0)
> 		return(Q[i--] = t);
> 	i = endQ-1;
> 	return(Q[0] = t);
> }
> 
> Best regards,
> 
> Guido Montorsi
> 
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