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real function da_unifva (kdum) ,2
!--------------------------------------------------------------------
! Purpose: Minimal random number generator of Park and Miller with
! Bays-Durham shuffle and added safeguards.
! Returns a uniform random deviate between 0.0. and 1.0 (exclusive
! of the endpoint values). Call with kdum a negative integer to
! initialize; thereafter, do not alter kdum between successive
! deviates in sequence. rnmx should approximate the largest
! floating value less than 1.
!
! See descripiton of function 'ran1', pg. 271.
!--------------------------------------------------------------------
implicit none
integer, intent(inout) :: KDUM
integer JPIA,JPIM,JPIQ,JPIR,JPNTAB,JPNDIV
real PPAM,PPEPS,PPRNMX
parameter(JPIA=16807,JPIM=2147483647,JPIQ=127773,JPIR=2836, &
JPNTAB=32,JPNDIV=1+(JPIM-1)/JPNTAB, &
PPAM=1./JPIM,PPEPS=1.2E-07,PPRNMX=1.-PPEPS)
integer JJ
integer IJJ,IK
integer NIV(JPNTAB),NIY
save NIV,NIY
DATA NIV /JPNTAB*0/, NIY /0/
if (trace_use_frequent) call da_trace_entry
("da_unifva")
! begin main
! ----------
if ((KDUM.LE.0).OR.(NIY.EQ.0)) then
KDUM = MAX(-KDUM , 1)
do JJ = JPNTAB+8,1,-1
IK = KDUM/JPIQ
KDUM = JPIA*(KDUM - IK*JPIQ) - JPIR*IK
if (KDUM.lt.0) KDUM = KDUM + JPIM
if (JJ.LE.JPNTAB) NIV(JJ) = KDUM
end do
NIY = NIV(1)
end if
IK = KDUM/JPIQ
KDUM = JPIA*(KDUM - IK*JPIQ) - JPIR*IK
if (KDUM.LT.0) KDUM = KDUM + JPIM
IJJ = 1 + NIY/JPNDIV
NIY = NIV(IJJ)
NIV(IJJ) = KDUM
DA_UNifVA = Min(PPAM*NIY , PPRNMX)
if (trace_use_frequent) call da_trace_exit("da_unifva")
end function da_unifva