From mboxrd@z Thu Jan 1 00:00:00 1970 To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> In-reply-to: Your message of "Sun, 02 Oct 2011 14:44:35 EDT." <1a3de3d2869ab078c9a4fdf9bce44982@brasstown.quanstro.net> References: <20111002163800.GA12773@polynum.com> <20111002175227.2D7F1B856@mail.bitblocks.com> <20111002184015.CD088B852@mail.bitblocks.com> <1a3de3d2869ab078c9a4fdf9bce44982@brasstown.quanstro.net> Date: Sun, 2 Oct 2011 12:14:31 -0700 From: Bakul Shah Message-Id: <20111002191431.D7DA7B852@mail.bitblocks.com> Subject: Re: [9fans] circular fonctions: precision? Topicbox-Message-UUID: 2fa44e80-ead7-11e9-9d60-3106f5b1d025 On Sun, 02 Oct 2011 14:44:35 EDT erik quanstrom wrote: > > IEEE754-1985 didn't specify circular, hyperbolic or other > > advanced functions. You can have 754 compliant hardware and > > not implement these functions. In any case the standard can > > not dictate the accuracy of functions not specified in it. An > > iterative algorithm may lose more than 1 bit of accuracy since > > iterations won't be done in infinite precision. One can not > > assume accuracy to a bit even where these functions are > > imeplemented in h/w. For x86, accuracy may be specified in > > some Intel or AMD manual. > > that wasn't my reading of the spec. so you're saying that if > the iterative algorithm loops 53 times, it's free to return any > answer whatever and still be compliant? That was my reading (but it was a long time ago and I am not a numerical analyst lawyer. So caveat emptor. You get what you pay for. etc.) But if you expect to sell your library presumably you'd care about the quality of impementation!