00001 #include "MusimatTutorial.h" 00002 MusimatTutorialSection(B0116) { 00003 Print("*** B.1.16 Conditional Statements ***"); 00004 /***************************************************************************** 00005 00006 B.1.16 Conditional Statements 00007 00008 A mathematical notation for determining the sign of a number is 00009 00010 | x < 0, a 00011 y = | 00012 | x >= 0, b 00013 00014 00015 which sets y to a if x is negative; otherwise it sets y to b. Such relational expressions are called 00016 predicates. Musimat accomplishes the same thing like this: 00017 *****************************************************************************/ 00018 00019 Real a = 1; 00020 Real b = 2; 00021 Real y = 5; 00022 00023 If (y < 0) 00024 y = a; 00025 Else 00026 y = b; 00027 00028 /***************************************************************************** 00029 In this example, y receives the value of a if y is less than 0; otherwise y receives the value of b. 00030 The Else part of this construction is optional. So for example, 00031 *****************************************************************************/ 00032 00033 If (a < b) 00034 Print(a); 00035 00036 /***************************************************************************** 00037 prints a only if it is less than b. If and Else can be combined to allow chains of predicates: 00038 *****************************************************************************/ 00039 Real r = -1.0; 00040 00041 If (a < 0) // is x negative? 00042 y = a; 00043 Else If (a == 0) // it's not negative, but is it zero? 00044 y = b; 00045 Else // neither negative nor zero, x must be positive 00046 y = r; 00047 00048 } 00049 00051 /* $Revision: 1.2 $ $Date: 2006/09/05 06:32:25 $ $Author: dgl $ $Name: $ $Id: B0116.cpp,v 1.2 2006/09/05 06:32:25 dgl Exp $ */ 00052 // The Musimat Tutorial © 2006 Gareth Loy 00053 // Derived from Chapter 9 and Appendix B of "Musimathics Vol. 1" © 2006 Gareth Loy 00054 // and published exclusively by The MIT Press. 00055 // This program is released WITHOUT ANY WARRANTY; without even the implied 00056 // warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 00057 // For information on usage and redistribution, and for a DISCLAIMER OF ALL 00058 // WARRANTIES, see the file, "LICENSE.txt," in this distribution. 00059 // "Musimathics" is available here: http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=10916 00060 // Gareth Loy's Musimathics website: http://www.musimathics.com/ 00061 // The Musimat website: http://www.musimat.com/ 00062 // This program is released under the terms of the GNU General Public License 00063 // available here: http://www.gnu.org/licenses/gpl.txt 00064
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