ran1.F

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!
! $Id: ran1.F 2239 2015-03-23 07:27:30Z emillour $
!
      FUNCTION ran1(IDUM)
      IMPLICIT NONE
      REAL RAN1
      REAL,SAVE :: R(97)
      REAL,PARAMETER :: RM1=3.8580247e-6,rm2=7.4373773e-6
      INTEGER,SAVE :: IFF=0
      integer,save :: ix1,ix2,ix3
      INTEGER,PARAMETER :: M1=259200,ia1=7141,ic1=54773
      INTEGER,PARAMETER :: M2=134456,ia2=8121,ic2=28411
      INTEGER,PARAMETER :: M3=243000,ia3=4561,ic3=51349
      INTEGER :: IDUM,J

      IF (idum.LT.0.OR.iff.EQ.0) THEN
        iff=1
        ix1=mod(ic1-idum,m1)
        ix1=mod(ia1*ix1+ic1,m1)
        ix2=mod(ix1,m2)
        ix1=mod(ia1*ix1+ic1,m1)
        ix3=mod(ix1,m3)
        DO 11 j=1,97
          ix1=mod(ia1*ix1+ic1,m1)
          ix2=mod(ia2*ix2+ic2,m2)
          r(j)=(REAL(ix1)+REAL(ix2)*RM2)*rm1
11      CONTINUE
        idum=1
      ENDIF
      ix1=mod(ia1*ix1+ic1,m1)
      ix2=mod(ia2*ix2+ic2,m2)
      ix3=mod(ia3*ix3+ic3,m3)
      j=1+(97*ix3)/m3
      IF(j.GT.97.OR.j.LT.1) stop 1
      ran1=r(j)
      r(j)=(REAL(ix1)+REAL(ix2)*RM2)*rm1
      RETURN
      END