Xref: utzoo comp.lang.misc:3520 comp.arch:11522 Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ncar!asuvax!mcdphx!udc!chant!aglew From: aglew@urbana.mcd.mot.com (Andy-Krazy-Glew) Newsgroups: comp.lang.misc,comp.arch Subject: Re: Fast conversions, another urban myth? Message-ID:Date: 26 Sep 89 00:11:58 GMT References: <832@dms.UUCP> <688@UALTAVM.BITNET> <9dAz02zs58y201@amdahl.uts.amdahl.com> <27935@winchester.mips.COM> <3902@yunexus.UUCP> <1741@sunset.MATH.UCLA.EDU> Sender: aglew@urbana.mcd.mot.com Organization: Work: Motorola MCD, Urbana Design Center; School: University of Illinois at Urbana-Champaign Lines: 23 In-reply-to: pmontgom@sonia.math.ucla.edu's message of 22 Sep 89 20:36:00 GMT Performing arithmetic in ASCII strings has the possible advantage that you are already wasting space, so you might want to consider using redundant arithmetic representations (eg. in base 10 allow your digits to range from -16 to +16) using the free space that the ASCII encoding provides (having paused to clear it out). If you are doing complicated calculations, this would mean that you do not have to worry about carry propagation in intermediate results (carries can only propagate one digit position in redundant arithmetic) until you finally have to output the data. I'm not suggesting hardware, just taking advantage of the technique in software. Ditto for extended precision -- do the folks who do really big extended precision (MACSYMA, MATHEMATICA, the guys who crunch big primes) use carry-free or carry-propagate arithmetic. Of course, business calculations are already fast enough... -- Andy "Krazy" Glew, Motorola MCD, aglew@urbana.mcd.mot.com 1101 E. University, Urbana, IL 61801, USA. {uunet!,}uiucuxc!udc!aglew My opinions are my own; I indicate my company only so that the reader may account for any possible bias I may have towards our products.