SUBROUTINE BGNRND(X0, X, A, MRND)

C     + + + PURPOSE + + +
C
C     BGNRND IS USED TO INITIALIZE THE SEED FOR THE RANDOM NUMBER
C     GENERATOR RND
C
C     THIS ROUTINE, WITH DEBUG LINES ACTIVATED, CHECKS TO SEE IF THE 
C     UNIFORM RANDOM NUMBER GENERATOR, RND, WILL WORK IN DOUBLE OR 
C     SINGLE PRECISION
C
C     TO CHANGE TO SINGLE PRECISION, COMMENT OUT THE DOUBLE PRECISION 
C     STATEMENTS IN BGNRND AND RND AND CHANGE THE DATA STATEMENTS IN 
C     RND TO HAVE SINGLE PRECISION NUMBERS
C
C     X0  R*4  THE ROUTINE INITIALIZES X TO MIN(MAX(INT(X0),1),M-1)  
C     THIS INSURES X IS INITIALLY POSITIVE AND LESS THAN M
C
C     CALLED FROM HDRIVE
C     AUTHOR(S): D. FLANAGAN, J. ASCOUGH
C     VERSION: THIS MODULE TAKEN FROM ASCOUGH STANDALONE IRS CODE
C     DATE CODED:  3-28-2005
C     CODED BY: D. FLANAGAN
C
C     + + + ARGUMENT DECLARATIONS + + +
C
      REAL X0, X, A, MRND
C      
C     + + + ARGUMENT DEFINITIONS + + +
C
C     X0      -
C     X       -
C     A       -
C     MRND    -
C
C     + + + LOCAL VARIABLES + + +
      DOUBLE PRECISION U
C
C     + + + END SPECIFICATIONS + + +

C
C     TEST FOR DOUBLE PRECISION OPERATION
C
      X = 1.D0
      A = 16807.D0
      MRND = 2147483647.D0
      X = A * MRND
      U = A
C
      IF (.NOT.((X.NE.X+1.D0).AND.(U.NE.U+1.))) THEN
         WRITE(*,*) 'RANDOM NUMBER INITIALIZATION FAILED'
         STOP
      END IF
C     
C     TEST FOR SINGLE PRECISION OPERATION
C     
      U = X
C     IF (U.NE.U+1.) THEN
C     END IF
C     
C     INITIALIZE X
C     
      X = AINT(X0)
      IF (X.LE.0.D0) X = 1.
      IF (X.GE.MRND) X = MRND - 1.D0
C
      RETURN
      END