Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.3 alpha 4/3/85; site ukma.UUCP Path: utzoo!watmath!clyde!cbosgd!ukma!sambo From: sambo@ukma.UUCP (Inventor of micro-S) Newsgroups: net.unix Subject: Re: Floating point numbers on the Pyramid Message-ID: <1925@ukma.UUCP> Date: Fri, 28-Jun-85 04:08:57 EDT Article-I.D.: ukma.1925 Posted: Fri Jun 28 04:08:57 1985 Date-Received: Sat, 29-Jun-85 01:21:42 EDT References: <292@eneevax.UUCP> <2405@topaz.ARPA> Reply-To: sambo@ukma.UUCP (Inventor of micro-S) Organization: Univ. of KY Mathematical Sciences Lines: 36 In article <2405@topaz.ARPA> vijay@topaz.ARPA (P. Vijay) writes: > Could someone tell me how the Pyramid 90x > does floating point numbers? Somebody told > me it was the IEEE floating point std. Everything you mentioned is specified by the IEEE standard. (Actually, I suppose you misquoted whatever source you used for the meanings of the single and double precision formats - when e = 0 or 255 for single and 0 or 2047 for double, the numbers are interpreted differently, so the formula you stated applies only for the range 0 < e < 255 for single, and 0 < e < 2047 for double.) If the Pyramid conforms to the IEEE standard, then it must also be able to simulate single-precision arithmetic (even if the numbers are all double-precision); it must have four rounding modes; it must be able to detect five different kinds of exceptions (invalid operation, division by zero, overflow, underflow, and inexact), possibly providing a way of doing exception handling; it must implement floating-point operations (including the basic arithmetic operations) in the manner specified; and it must have at least two different kinds of NaNs (Not a Number) and both a positive and negative infinity. I'm not sure to what address you should write to get a copy of the standard, though I'm sure you can find out by contacting Richard Karpinski at: Dick Karpinski Manager of Unix Services, UCSF Computer Center UUCP: ...!ucbvax!ucsfcgl!cca.ucsf!dick (415) 666-4529 (12-7) BITNET: dick@ucsfcca Compuserve: 70215,1277 Telemail: RKarpinski USPS: U-76 UCSF, San Francisco, CA 94143 I have a copy of the IEEE P754 Draft 10.1 of the standard in front of me, which I have been told has been adopted as the official standard. ----------------------------------------- Samuel A. Figueroa, Dept. of CS, Univ. of KY, Lexington, KY 40506-0027 ARPA: ukma!sambo<@ANL-MCS>, or sambo%ukma.uucp@anl-mcs.arpa, or even anlams!ukma!sambo@ucbvax.arpa UUCP: {ucbvax,unmvax,boulder,oddjob}!anlams!ukma!sambo, or cbosgd!ukma!sambo "Micro-S is great, if only people would start using it."