00001 #include "MusimatChapter9.h" 00002 MusimatChapter9Section(C090703b) { 00003 Print("*** Random Real Numbers ***"); 00004 /***************************************************************************** 00005 00006 Random Real Numbers 00007 00008 The LCRandom() method returns integers between 0 and c. It is straightforward 00009 to map its output to any range of Real values between an upper bound U and a 00010 lower bound L, as shown in the Random function, below. 00011 *****************************************************************************/ 00012 para1(); // Step into this function to continue. 00013 } 00014 00015 /***************************************************************************** 00016 luRandom() is a copy of the Musimat Random() function defined in Random.cpp, 00017 reproduced here for dydactic reasons (to keep things simple). 00018 *****************************************************************************/ 00019 Real luRandom(Real L = 0.0, Real U = 1.0) { 00020 Static Const Integer c = Musimat_Random_Seed; // defined in Random.h 00021 Integer i = LCRandom(); // get a random integer value 00022 Real r = Real(i); // convert it to a real value 00023 r = r/Real(c); // scale it to 0.0 <= r < 1.0 00024 Return(r * (U - L) + L); // scale it to the range L to U 00025 } 00026 00027 Static Void para1() { 00028 /***************************************************************************** 00029 First, we use LCRandom() to get a random integer. Recall that LCRandom() 00030 forces the result to be positive. We promote its random integer result to 00031 Real and store it in r. Next, we divide it by c so its range is 0.0 <= r < 1.0. 00032 Finally, we scale it by the difference between U and L, and add L, so that 00033 the random value is bounded above by U and below by L. That way we can get 00034 a random result from a particular range of values that we can stipulate. 00035 00036 Here is an example of invoking this Real Random() method: 00037 *****************************************************************************/ 00038 00039 Print("*** Ten invocations of luRandom() ***"); 00040 RealList x; 00041 00042 For (Integer i = 0; i < 10; i++ ) { 00043 x[i] = luRandom(0.0, 1.0); 00044 } 00045 00046 Print( x ); 00047 00048 /***************************************************************************** 00049 luRandom() is declared above with initializing values for its 00050 two arguments. This means luRandom() can be called with 0, 1, or 2 arguments. 00051 If called with zero arguments, both initial values are employed; if called with one 00052 argument, only the second initial value is employed; if called with two arguments, 00053 the initial values are ignored. 00054 Initial value for L defaults to 0.0, and U defaults to 1.0. Thus, to 00055 get a number in the unsigned unit interval [0,1), it suffices to invoke 00056 luRandom() without arguments, as follows: 00057 *****************************************************************************/ 00058 Print("*** Various Calls to luRandom() ***"); 00059 Real r = luRandom(); 00060 Print(r); 00061 Print("luRandom(37.5, 37.9)=", luRandom(37.5, 37.9)); 00062 00063 } 00064 00066 /* $Revision: 1.3 $ $Date: 2006/09/05 08:02:45 $ $Author: dgl $ $Name: $ $Id: C090703b.cpp,v 1.3 2006/09/05 08:02:45 dgl Exp $ */ 00067 // The Musimat Tutorial � 2006 Gareth Loy 00068 // Derived from Chapter 9 and Appendix B of "Musimathics Vol. 1" � 2006 Gareth Loy 00069 // and published exclusively by The MIT Press. 00070 // This program is released WITHOUT ANY WARRANTY; without even the implied 00071 // warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 00072 // For information on usage and redistribution, and for a DISCLAIMER OF ALL 00073 // WARRANTIES, see the file, "LICENSE.txt," in this distribution. 00074 // "Musimathics" is available here: http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=10916 00075 // Gareth Loy's Musimathics website: http://www.musimathics.com/ 00076 // The Musimat website: http://www.musimat.com/ 00077 // This program is released under the terms of the GNU General Public License 00078 // available here: http://www.gnu.org/licenses/gpl.txt
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