C:/Musimathics_local/Musimat/include/Random.h

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/* $Revision: 1.4 $ $Date: 2006/09/12 17:37:41 $ $Author: dgl $ $Name:  $ $Id: _random_8h-source.html,v 1.4 2006/09/12 17:37:41 dgl Exp $ */
#ifndef RANDOM_H
#define RANDOM_H

// The Musimat Tutorial © 2006 Gareth Loy
// Derived from Chapter 9 and Appendix B of "Musimathics Vol. 1" © 2006 Gareth Loy 
// and published exclusively by The MIT Press.
// This program is released WITHOUT ANY WARRANTY; without even the implied 
// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
// For information on usage and redistribution, and for a DISCLAIMER OF ALL
// WARRANTIES, see the file, "LICENSE.txt," in this distribution.
// "Musimathics" is available here:     http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=10916
// Gareth Loy's Musimathics website:    http://www.musimathics.com/
// The Musimat website:                 http://www.musimat.com/
// This program is released under the terms of the GNU General Public License
// available here:                      http://www.gnu.org/licenses/gpl.txt

#include "Aliases.h"



class Random {

public:

        Random(Integer a = 16807, Integer b = 0, Integer c = 2147483647) : m_a(a), m_b(b), m_c(c) { m_x = 1; }

        Integer lCRandom( ) {
                m_x = mod( m_a * m_x + m_b, m_c );      // update x based on its previous value
                Integer r = m_x;
                If ( r < 0 )                                            // force the result to be positive                                                      
                        r = -r; 
                Return( r ); 
        }

        Real random( Real L, Real U ) {
                Real r = lCRandom();
                r = r / Real( m_c );
                Return( r * ( U - L ) + L );
        }

        Integer random( Integer L, Integer U ) {
                Real i = random( Real( L ), U + 1.0 );
                Return( Integer( i ) );
        }

        Integer seed( Integer s ) {
                Integer r = m_x;
                m_x = s;
                Return( r );
        }

        Integer getTime();

private:
        Const Integer m_a;
        Const Integer m_b;
        Const Integer m_c;
        Integer m_x;                                            

# if 0
        // This is the didactic method for modulo arithmetic described in "Musimathics"
        Integer mod( Integer j, Integer k ) {
                While ( j >= k ) { j = j - k; }
                While ( j <= -k ) { j = j + k; }
                Return( j );
        }
# else
        // We'll use the built-in mod operator instead for speed
        Integer mod( Integer j, Integer k ) {
                Return j % k; 
        }
#endif
};

Integer LCRandom( );

Integer IRandom( Integer L, Integer U );

Integer SeedRandom( Integer seed );

Integer Time();

Real Random( Real L = 0.0, Real U = 1.0 );

Integer Random( Integer L, Integer U );

#endif // RANDOM_H

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