From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: tuhs-bounces@minnie.tuhs.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.2 Received: from minnie.tuhs.org (minnie.tuhs.org [45.79.103.53]) by inbox.vuxu.org (OpenSMTPD) with ESMTP id dbd029e9 for ; Sat, 27 Oct 2018 14:51:39 +0000 (UTC) Received: by minnie.tuhs.org (Postfix, from userid 112) id 038F3A21B7; Sun, 28 Oct 2018 00:51:38 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 0532094BB2; Sun, 28 Oct 2018 00:51:20 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id 6ED1E94BB2; Sun, 28 Oct 2018 00:18:08 +1000 (AEST) Received: from ipo7.cc.utah.edu (ipo7.cc.utah.edu [155.97.144.42]) by minnie.tuhs.org (Postfix) with ESMTPS id 4B5E194113 for ; Sun, 28 Oct 2018 00:18:07 +1000 (AEST) X-IronPort-AV: E=Sophos;i="5.54,432,1534831200"; d="scan'208";a="653676902" Received: from mail.math.utah.edu ([155.101.98.135]) by ipo7smtp.cc.utah.edu with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 27 Oct 2018 08:18:06 -0600 Received: from gamma.math.utah.edu (gamma.math.utah.edu [155.101.96.20]) by mail.math.utah.edu (8.14.8/8.14.8) with ESMTP id w9REI64v025077; Sat, 27 Oct 2018 08:18:06 -0600 (MDT) Received: from gamma.math.utah.edu (localhost [127.0.0.1]) by gamma.math.utah.edu (8.15.1/8.15.1) with ESMTP id w9REI6Ic153886; Sat, 27 Oct 2018 08:18:06 -0600 Received: (from beebe@localhost) by gamma.math.utah.edu (8.15.1/8.15.1/Submit) id w9REI63r153884; Sat, 27 Oct 2018 08:18:06 -0600 Date: Sat, 27 Oct 2018 08:18:06 -0600 From: "Nelson H. F. Beebe" To: tuhs@minnie.tuhs.org X-US-Mail: "Department of Mathematics, 110 LCB, University of Utah, 155 S 1400 E RM 233, Salt Lake City, UT 84112-0090, USA" X-Telephone: +1 801 581 5254 X-FAX: +1 801 581 4148 X-URL: http://www.math.utah.edu/~beebe Message-ID: X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.3.8 (mail.math.utah.edu [155.101.98.135]); Sat, 27 Oct 2018 08:18:06 -0600 (MDT) Subject: Re: [TUHS] Reconstructed and newly set UNIX Manual X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" Angelo Papenhoff writes about the conversion of printer points to other units: >> >From my experience in the world of prepress 723pts == 10in. >> >> Then Adobe unleashed PostScript on us and redefined the point >> so that 72pt == 1in. >> >> Ibunaware of any other definitions of a point. The most important other one is that used by the TeX typesetting system: 72.27pt is one inch. TeX calls the Adobe PostScript one a big point: 72bp == 1in. Here is what Don Knuth, TeX's author, wrote on page 58 of The TeXbook (Addison-Wesley, 1986, ISBN 0-201-13447-0): >> ... >> The units have been defined here so that precise conversion to sp >> is efficient on a wide variety of machines. In order to achieve >> this, TeX's ``pt'' has been made slightly larger than the official >> printer's point, which was defined to equal exactly .013837in by >> the American Typefounders Association in 1886 [cf. National Bureau >> of Standards Circular 570 (1956)]. In fact, one classical point is >> exactly .99999999pt, so the ``error'' is essentially one part in >> 10^8. This is more than two orders of magnitude less than the >> amount by which the inch itself changed during 1959, when it >> shrank to 2.54cm from its former value of (1/0.3937)cm; so there >> is no point in worrying about the difference. The new definition >> 72.27pt=1in is not only better for calculation, it is also easier >> to remember. >> ... Here sp is a scaled point: 65536sp = 1pt. The distance 1sp is smaller than the wavelength of visible light, and is thus not visible to humans. TeX represents physical dimensions as integer numbers of scaled points, or equivalently, fixed-point numbers in points, with a 16-bit fraction. With a 32-bit word size, that leaves 16 bits for the integer part, of which the high-order bit is a sign, and the adjacent bit is an overflow indicator. That makes TeX's maximum dimension on such machines 1sp below 2^14 (= 16,384) points, or about 5.75 meters or 18.89 feet. ------------------------------------------------------------------------------- - Nelson H. F. Beebe Tel: +1 801 581 5254 - - University of Utah FAX: +1 801 581 4148 - - Department of Mathematics, 110 LCB Internet e-mail: beebe@math.utah.edu - - 155 S 1400 E RM 233 beebe@acm.org beebe@computer.org - - Salt Lake City, UT 84112-0090, USA URL: http://www.math.utah.edu/~beebe/ - -------------------------------------------------------------------------------