Return to BSD News archive
Newsgroups: comp.os.386bsd.questions Path: sserve!newshost.anu.edu.au!munnari.oz.au!spool.mu.edu!agate!dog.ee.lbl.gov!network.ucsd.edu!pacbell.com!amdahl!hip-hop!dfox From: dfox@hip-hop.suvl.ca.us (David Fox) Subject: Re: Problems with g++2.3.3 and leda Keywords: g++2.3.3, leda References: <1qjd46$vc4@obelix.uni-muenster.de> <1qr1uu$1hck@hal.gnu.ai.mit.edu> Organization: Hip-Hop BBS, Sunnyvale California Date: Sun, 18 Apr 1993 18:18:30 GMT Message-ID: <C5oyuv.AnL@hip-hop.suvl.ca.us> Lines: 30 mycroft@hal.gnu.ai.mit.edu (Charles Hannum) wrote: > >In article <1qjd46$vc4@obelix.uni-muenster.de> >frido@math.uni-muenster.de writes: >> >> After debugging the programm with gdb I found that the line where the >> exception happens seems quite harmless. It is a comparison of a >> double variable and zero (double l; if (l==0) ...). > >Unfortunately, floating point exceptions are not precise; i.e. the >processor is not left in the state it was at the time the instruction This is quite true, of course. But the earlier poster found something that isn't exactly harmless. One should never compare a floating point value with integer zero. I suppose one could cast 0 to double so that a proper set of instructions are generated so that the variable is compared to 'fldz', but still, the proper way to do it is to compare the two values within some minimal tolerance. >-- > \ / Charles Hannum, mycroft@ai.mit.edu > /\ \ PGP public key available on request. MIME, AMS, NextMail accepted. >Scheme White heterosexual atheist male (WHAM) pride! -- David E. Fox email: hip-hop!dfox@amdahl.com 5479 Castle Manor Drive San Jose, CA 95129 Thanks for letting me change the magnetic 408/ 253-7992 images on your hard drive.