RANUM.F

      FUNCTION RANUM()
      
      COMMON /RAN/RRN(54), KRANUM, RLIMIT, NRNOPT, ITAPE

C RANDOM NUMBER RETURNED AS VALUE OF RANUM =.0-1. FROM SOURCE-
C        -RANF(0),   SYSTEM FUNCTION,  IF NRNOPT=1
C        -TAPE OF RANDOM NUMBERS IF NRNOPT=2,  REQUIRES REQUEST I.E.
C                -REQUEST(TAPE50,987,MT,HI,READ) IN CONTROL CARDS.

      IF(NRNOPT-1) 2, 2, 20

C MTP: REPLACED RANF FROM CDC FORTRAN WITH GFORTRAN'S RAND
2     RANUM = RAND(0)
      RETURN
20    KRANUM = KRANUM + 1
      IF(KRANUM-55) 28, 26, 28
26    KRANUM = 1
28    IF(KRANUM-1) 50, 40, 50
C MTP: BROUGHT THIS IN BECAUSE GFORTRAN DIDN'T LIKE THE EOF IF STATEMENT
40    READ(ITAPE, IOSTAT=IOSTATUS) RRN
      IF (IOSTATUS .NE. 0) THEN
            REWIND ITAPE
            GO TO 40
      END IF
50    RANUM = RRN(KRANUM)
      RANUM = RANUM / RLIMIT

      RETURN
      END

C 40    READ(ITAPE) RRN
C       IF(EOF, ITAPE) 41, 50
C 41    REWIND ITAPE
C       GO TO 40