00001 #include "MusimatChapter9.h" 00002 MusimatChapter9Section(C090703c) { 00003 Print("*** Random Integer Numbers Scaled to an Arbitrary Range ***"); 00004 /***************************************************************************** 00005 00006 Random Integer Numbers Scaled to an Arbitrary Range 00007 00008 *****************************************************************************/ 00009 para1(); // Step into this function to continue. 00010 para2(); // Step into this function to continue. 00011 } 00012 00013 Static Void para1() { 00014 /***************************************************************************** 00015 We can adapt the Random() function to return integers within a specified 00016 integer range. When a real value is converted to an integer, we truncate 00017 (discard) the fractional part, leaving the integer part. For example, 00018 *****************************************************************************/ 00019 00020 Print("*** Example of Truncation ***"); 00021 Real r = 3.14159; 00022 Print("Real r = ", r); 00023 Integer i = Integer(r); 00024 Print("Truncated = ", i); 00025 00026 /***************************************************************************** 00027 prints 3. Truncation is equivalent to the floor function. 00028 00029 The iRandom() function below is a method to generate integer random values over 00030 an integer range. It uses the Musimat library Real Random(Real, Real) function 00031 to return a Real numerical range, then truncates the result to an integer by type 00032 casting the result to type Integer. This behavior is identical to the Musimat 00033 function Integer Random(Integer, Integer), but is reproduced here for dydactic 00034 reasons (to keep things simple). 00035 *****************************************************************************/ 00036 } 00037 00038 Integer iRandom(Integer L, Integer U) { 00039 Real rL = L; // convert L to Real 00040 Real rU = U + 1.0; // convert U to Real, add 1.0 00041 Real x = Random(rL, rU); // get a Real random value 00042 Return( Integer(x) ); // return result as an Integer 00043 } 00044 00045 Static Void para2() { 00046 /***************************************************************************** 00047 Note that I added 1.0 to the upper real boundary in iRandom(). Truncation of the random 00048 result necessitates slightly increasing the top end of the range of choice. 00049 For example, in order to choose a value in the integer range 0 to 9, we must 00050 generate a random real value x that lies in the range 0.0 <= x < 10.0. This 00051 gives an equal chance of obtaining an integer in the range 0 to 9. 00052 00053 Here are ten values generated by iRandom() over the interval [0,10]. 00054 *****************************************************************************/ 00055 Print("*** Example of Random Integer Values in the Interval [0,10] ***"); 00056 IntegerList x; 00057 00058 For ( Integer i = 0; i < 10; i = i + 1 ) { 00059 x[i] = iRandom( 0, 10 ); 00060 } 00061 00062 Print( x ); 00063 00064 } 00065 00067 /* $Revision: 1.3 $ $Date: 2006/09/05 08:02:45 $ $Author: dgl $ $Name: $ $Id: C090703c.cpp,v 1.3 2006/09/05 08:02:45 dgl Exp $ */ 00068 // The Musimat Tutorial � 2006 Gareth Loy 00069 // Derived from Chapter 9 and Appendix B of "Musimathics Vol. 1" � 2006 Gareth Loy 00070 // and published exclusively by The MIT Press. 00071 // This program is released WITHOUT ANY WARRANTY; without even the implied 00072 // warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 00073 // For information on usage and redistribution, and for a DISCLAIMER OF ALL 00074 // WARRANTIES, see the file, "LICENSE.txt," in this distribution. 00075 // "Musimathics" is available here: http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=10916 00076 // Gareth Loy's Musimathics website: http://www.musimathics.com/ 00077 // The Musimat website: http://www.musimat.com/ 00078 // This program is released under the terms of the GNU General Public License 00079 // available here: http://www.gnu.org/licenses/gpl.txt
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