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Date:      Tue, 27 Aug 2013 00:30:12 +1000 (EST)
From:      Bruce Evans <brde@optusnet.com.au>
To:        Steve Kargl <sgk@troutmask.apl.washington.edu>
Cc:        freebsd-numerics@freebsd.org, Bruce Evans <brde@optusnet.com.au>
Subject:   Re: (2nd time) tweaks to erff() threshold values
Message-ID:  <20130827002821.K2328@besplex.bde.org>
In-Reply-To: <20130823171526.GA47736@troutmask.apl.washington.edu>
References:  <20130822213315.GA6708@troutmask.apl.washington.edu> <20130823202257.Q1593@besplex.bde.org> <20130823171526.GA47736@troutmask.apl.washington.edu>

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On Fri, 23 Aug 2013, Steve Kargl wrote:

> On Fri, Aug 23, 2013 at 09:12:33PM +1000, Bruce Evans wrote:
>>
>> @ 	if(ix < 0x3f580000) {		/* |x|<0.84375 */
>> @ 	    if(ix < 0x38800000) { 	/* |x|<2**-14 */
>> @ 	        if (ix < 0x04000000)	/* |x|<0x1p-119 */
>> @ 		    return (8*x+efx8*x)/8;  /*avoid spurious underflow */
>
> To keep the diff between s_erf.c and s_erff.c small, do you
> want my to update s_erf.c with the last line above?

Yes, including the style change from *0.125 to /8 and any similar style
changes you can find (or don't change this anywhere), and the comment
on the threshold for underflow.

Bruce



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