Article View: comp.arch
Article #12260Re: Implementing Interval Arithmetic with IEEE rounding modes
From: Arch D. Robison
Date: Wed, 26 Jun 1991 02:57
Date: Wed, 26 Jun 1991 02:57
15 lines
1113 bytes
1113 bytes
There have been comments that changing the rounding mode on some machines can be slow. But does it really need to be changed? IEEE arithmetic is symmetric with regard to +/-, and we have the identity: ceiling(x) = -floor(-x) So by flipping signs, we can stay in round-down mode all the way. Better yet, instead of storing an interval as (lower,upper), store it as (lower,-upper) and avoid flipping signs. Then two intervals can be added with a single setting of the rounding mode to ``round-down'' and two addition instructions. Arch D. Robison robison@shell.com Bellaire Research Center (713)-245-7240 Shell Development Company
Technical Details
Message-ID:
<1991Jun26.025738.18876@shell.shell.com>Path:
arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!cis.ohio-state.edu!pacific.mps.ohio-state.edu!linac!convex!bcm!shell!brazil!robisonShow Full Headers
Complete Article Headers
Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!cis.ohio-state.edu!pacific.mps.ohio-state.edu!linac!convex!bcm!shell!brazil!robison From: robison@brazil (Arch D. Robison) Newsgroups: comp.arch Subject: Re: Implementing Interval Arithmetic with IEEE rounding modes Message-ID: <1991Jun26.025738.18876@shell.shell.com> Date: 26 Jun 91 02:57:38 GMT Sender: Arch D. Robison Organization: Shell Development Lines: 15