ExpressionRandom.h

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#ifndef OPALX_ExpressionRandom_HH
#define OPALX_ExpressionRandom_HH
 
// ------------------------------------------------------------------------
// $RCSfile: ExpressionRandom.h,v $
// ------------------------------------------------------------------------
// $Revision: 1.1.1.1 $
// ------------------------------------------------------------------------
// Copyright: see Copyright.readme
// ------------------------------------------------------------------------
//
// Class: Random
//
// ------------------------------------------------------------------------
// Class category: Utilities
// ------------------------------------------------------------------------
//
// $Date: 2000/03/27 09:32:38 $
// $Author: fci $
//
// ------------------------------------------------------------------------
 
// the random numbers are generated in batches of 55
const int nr = 55;
 
// the random integers are generated in the range [0, MAXRAN)
static const int maxran = 1000000000;
 
// This generator is based on:
// [center]
// D. Knuth: The Art of Computer Programming, Vol. 2, 2nd edition.
// [/center]
 
class Random {
public:
    Random();
 
    //  The argument is the new seed, an integer in the range [0, 1000000000].
    Random(int seed);
 
    ~Random();
 
    //  The argument is the new seed, an integer in the range [0, 1000000000].
    void reseed(int seed = 123456789);
 
    //  Return a real pseudo-random number in the range [0,1).
    double uniform();
 
    //  Return two real Gaussian pseudo-random numbers with unit standard
    //  deviation.  The values are placed in the two arguments.
    void gauss(double& gr1, double& gr2);
 
    //  Return an integer pseudo-random number in the range [0,1000000000).
    int integer();
 
    void init55(int seed);
 
private:
    // generate next batch of random numbers
    void irngen();
 
    // a set of "NR" random integers
    int irn[nr];
 
    // the next item to be used in the random sequence
    int next;
};
 
#endif  // OPALX_ExpressionRandom_HH