Article View: comp.lang.fortran
Article #6507Re: Precision of floating point multiply
From: Ron Shepard
Date: Mon, 29 Sep 2003 15:53
Date: Mon, 29 Sep 2003 15:53
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2680 bytes
In article <xrXdb.631209$Ho3.121609@sccrnsc03>, "Glen Herrmannsfeldt" <gah@ugcs.caltech.edu> wrote: > I thought it was somewhere in the thread, but maybe not. > > For C=C+A*B, single precision A, B, and double precision C: > > LE 0,A load single precision A > ME 0,B Multiply by B generating double product in float register 0 > SDR 2,2 Clear double float register 2 > LER 2,0 copy single value from reg 0 to reg 2 > AD 2,C add double C > STD 2,C store double into C > > The SDR and LER are used to clear the low half of the product. Are the exponents converted automatically with these instructions? If they aren't, then it seems odd to be able to convert between a double precision floating point value to a single precision value just by loading the value into a register. $.02 -Ron Shepard
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: fd4af,7830916812112af0 X-Google-Attributes: gidfd4af,public X-Google-Thread: fd705,7830916812112af0 X-Google-Attributes: gidfd705,public X-Google-Thread: 102b75,7830916812112af0 X-Google-Attributes: gid102b75,public X-Google-Thread: 1094ba,7830916812112af0 X-Google-Attributes: gid1094ba,public X-Google-ArrivalTime: 2003-09-29 08:53:35 PST Path: arc1-ca.pugleaf.net!news1.google.com!newsfeed.stanford.edu!logbridge.uoregon.edu!arclight.uoregon.edu!wn13feed!wn11feed!wn14feed!worldnet.att.net!216.166.71.14!border3.nntp.aus1.giganews.com!intern1.nntp.aus1.giganews.com!nntp.giganews.com!nntp.comcast.com!news.comcast.com.POSTED!not-for-mail NNTP-Posting-Date: Mon, 29 Sep 2003 10:53:33 -0500 From: Ron Shepard <ron-shepard@NOSPAM.comcast.net> Newsgroups: comp.lang.fortran,comp.arch,bit.listserv.ibm-main,alt.folklore.computers Subject: Re: Precision of floating point multiply Organization: little, if any References: <dG4db.598668$uu5.97984@sccrnsc04> <iu6fnvch0g09q9f335tt89ogfcj5jm2ovh@4ax.com> <kmRdb.626671$YN5.452649@sccrnsc01> <bl8q1g$iv7$1@pegasus.csx.cam.ac.uk> <xrXdb.631209$Ho3.121609@sccrnsc03> User-Agent: MT-NewsWatcher/3.3b1 (PPC Mac OS X) Date: Mon, 29 Sep 2003 10:53:38 -0500 Message-ID: <ron-shepard-609A55.10533829092003@news.comcast.giganews.com> Lines: 22 NNTP-Posting-Host: 12.250.133.181 X-Trace: sv3-5aDMg4ETO5lwXauMPFhHJz6aOcCu8+on4QT3hMXlC0VwJM/Y8pZWmGdqW6KGPL382CNAhkDjXc110Vr!nCj7+2oQsJVrTEvV575LQm+mr4DutjRFBL/03OWb4E0BnTQITAbGo6eqBT6PIOBTnAPl4S+gtgpY!2/NdQxYefL7r0jnR89Kr X-Complaints-To: abuse@comcast.net X-DMCA-Complaints-To: dmca@comcast.net X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.1