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Re: [Axiom-developer] Left shifts of negative numbers

From: Dylan Thurston
Subject: Re: [Axiom-developer] Left shifts of negative numbers
Date: Tue, 14 Oct 2003 21:30:40 -0400
User-agent: Mutt/1.5.4i

On Tue, Oct 14, 2003 at 09:09:50PM -0400, Page, Bill wrote:
> Does
>   shift(x,y) == -integer(ASH(-x,y)$Lisp
> involve two (potential long) integer multiplications?
> I.e. -1*integer(ASH(-1*x,y)$Lisp

I don't know whether adding/subtracting 1 or negation will be faster,
but either one should be faster than any multiplication (unless
multiplication by -1 is special cased somewhere).  There are no carries
to worry about.

I suspect the additions are probably faster, actually.


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