/*
!-------------------------------------------------------------------------!
!									  !
!	 N  A  S     P A R A L L E L	 B E N C H M A R K S  3.0	  !
!									  !
!			J A V A 	V E R S I O N			  !
!									  !
!                              R A N D O M                                !
!                                                                         !
!-------------------------------------------------------------------------!
!                                                                         !
!    This benchmark is a serial version of the NPB_JAV Random number   !
!    generating code.                                                     !
!									  !
!    Permission to use, copy, distribute and modify this software	  !
!    for any purpose with or without fee is hereby granted.  We 	  !
!    request, however, that all derived work reference the NAS  	  !
!    Parallel Benchmarks 3.0. This software is provided "as is" 	  !
!    without express or implied warranty.				  !
!									  !
!    Information on NPB 3.0, including the Technical Report NAS-02-008	  !
!    "Implementation of the NAS Parallel Benchmarks in Java",		  !
!    original specifications, source code, results and information	  !
!    on how to submit new results, is available at:			  !
!									  !
!	    http://www.nas.nasa.gov/Software/NPB/			  !
!									  !
!    Send comments or suggestions to  npb@nas.nasa.gov  		  !
!									  !
!	   NAS Parallel Benchmarks Group				  !
!	   NASA Ames Research Center					  !
!	   Mail Stop: T27A-1						  !
!	   Moffett Field, CA   94035-1000				  !
!									  !
!	   E-mail:  npb@nas.nasa.gov					  !
!	   Fax:     (650) 604-3957					  !
!									  !
!-------------------------------------------------------------------------!
!     Translation to Java and to MultiThreaded Code:			  !
!     Michael A. Frumkin					          !
!-------------------------------------------------------------------------!
*/
package NPB_JAV;

public class Random{

  //default seed
  public double tran = 314159265.0;   //First 9 digits of PI
  //Random Number Multiplier
  public double amult = 1220703125.0; //=Math.pow(5.0,13);
  public int KS=0;
  public double R23, R46, T23, T46;
  //constants
  public static final double d2m46=Math.pow(0.5,46);
  protected static final long i246m1 = (long)Math.pow(2,46)-1;
  
  public Random(){}
  public Random(double sd){seed=sd;}
  //Random number generator with an external seed
  public double randlc(double x, double a){
    double y[],r23,r46,t23,t46,t1,t2,t3,t4,a1,a2,x1,x2,z;
    r23 = Math.pow(0.5,23); 
    r46 = Math.pow(r23, 2); 
    t23 = Math.pow(2.0,23);
    t46 = Math.pow(t23, 2);
//---------------------------------------------------------------------
//   Break A into two parts such that A = 2^23 * A1 + A2.
//---------------------------------------------------------------------
    t1 = r23 * a;
    a1 = (int) t1;
    a2 = a - t23 * a1;
//---------------------------------------------------------------------
//   Break X into two parts such that X = 2^23 * X1 + X2, compute
//   Z = A1 * X2 + A2 * X1  (mod 2^23), and then
//   X = 2^23 * Z + A2 * X2  (mod 2^46).
//---------------------------------------------------------------------
    t1 = r23 * x;
    x1 = (int) t1;
    x2 = x - t23 * x1;
    t1 = a1 * x2 + a2 * x1;
    t2 = (int) (r23 * t1);
    z = t1 - t23 * t2;
    t3 = t23 * z + a2 * x2;
    t4 = (int) (r46 * t3);
    x = t3 - t46 * t4;
    return x;
  }
  //Random number generator with an internal seed
  public double randlc(double a){
    double y[],r23,r46,t23,t46,t1,t2,t3,t4,a1,a2,x1,x2,z;
    r23 = Math.pow(0.5,23); 
    r46 = Math.pow(r23, 2); 
    t23 = Math.pow(2.0,23);
    t46 = Math.pow(t23, 2);
//---------------------------------------------------------------------
//   Break A into two parts such that A = 2^23 * A1 + A2.
//---------------------------------------------------------------------
    t1 = r23 * a;
    a1 = (int) t1;
    a2 = a - t23 * a1;
//---------------------------------------------------------------------
//   Break X into two parts such that X = 2^23 * X1 + X2, compute
//   Z = A1 * X2 + A2 * X1  (mod 2^23), and then
//   X = 2^23 * Z + A2 * X2  (mod 2^46).
//---------------------------------------------------------------------
    t1 = r23 * tran;
    x1 = (int) t1;
    x2 = tran - t23 * x1;
    t1 = a1 * x2 + a2 * x1;
    t2 = (int) (r23 * t1);
    z = t1 - t23 * t2;
    t3 = t23 * z + a2 * x2;
    t4 = (int) (r46 * t3);
    tran = t3 - t46 * t4;
    return(r46 * tran);
  }
  public double vranlc(double n, double x, double a, double y[],int offset){ 
    long Lx = (long)x;
    long La = (long)a;

    for(int i=0;i<n;i++){
      Lx   = (Lx*La) & (i246m1);
      y[offset+i] = (double)(d2m46* Lx);
    }
    return (double) Lx;
  }
  public double seed;
  public double ipow46(double a, int exponent ){
      int n, n2;
      double q, r;
//---------------------------------------------------------------------
// Use
//   a^n = a^(n/2)*a^(n/2) if n even else
//   a^n = a*a^(n-1)       if n odd
//---------------------------------------------------------------------
      if (exponent == 0) return seed;
      q = a;
      r = 1;
      n = exponent;

      while(n>1){
         n2 = n/2;
         if (n2*2==n){
            seed = randlc(q,q);
	    q=seed;
            n = n2;
         }else{
            seed = randlc(r,q);
	    r=seed;
            n = n-1;
	 }
      }
      seed = randlc(r,q);
      return seed;
  }
  public double power( double a, int n ){
//c---------------------------------------------------------------------
//c     power  raises an integer, disguised as a double
//c     precision real, to an integer power
//c---------------------------------------------------------------------
      double aj,ajj,pow;
      int nj;

      pow = 1.0;
      nj = n;
      aj = a;
      while( nj != 0 ){
        if( nj%2==1 ) {
	  seed=randlc( pow, aj );
	  pow=seed;
	}
	ajj=aj;
        seed=randlc( aj, ajj );
	aj=seed;
        nj = nj/2;
      }
      return pow;
   }
}