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Re: [PATCH] Evaluate pow(x,n) at compile time
- From: Brad Lucier <lucier at math dot purdue dot edu>
- To: jsm28 at cam dot ac dot uk (Joseph S. Myers)
- Cc: lucier at math dot purdue dot edu (Brad Lucier), geoffk at geoffk dot org, gcc-patches at gcc dot gnu dot org, roger at www dot eyesopen dot com
- Date: Thu, 10 Apr 2003 18:15:05 -0500 (EST)
- Subject: Re: [PATCH] Evaluate pow(x,n) at compile time
>
> On Thu, 10 Apr 2003, Brad Lucier wrote:
>
> > So, practically speaking, it may be off by more than 1/2 bit for FP formats
> > that use two IEEE doubles (106 bit mantissa) or for other 128-bit formats.
>
> It should be straighforward to construct examples for such formats that do
> need about 2k bits and hopefully show the problem with GCC's
> implementation.
Well, the coding is straightforward, but it could take a *long* time in
Maple to construct the test vectors; "long" is at least a day (how long
I let it run on my ultrasparc without results) and it could be weeks or
months as far as I know.
Brad