function isclrp(irpa)
c
c this routine takes the rpa setting irpa and 
c      returns an index from 1 to 32.
c
c v1.0 jfe johnson 25 jul 82
c based on the routine sclrpa written by j.l.green 11/1/81
c last mods jfej 25 jul 82 updates to lkurpa table
	integer lkurpa(32)
c the values contained in lkurpa (lookup-rpa) array are rpa settings
c these settings corespond to the following rpa values
c	 0.00  0.10  0.15  0.20  0.25  0.35  0.45  0.55
c	 0.75  1.00  1.25  1.60  2.00  2.50  3.25  4.25
c	 5.25  6.50  8.50  11.0  12.5  14.0  16.0  18.0
c	 20.5  23.0  26.5  30.0  34.5  39.0  44.5  50.0
c	data lkurpa/  0,   2,   3,   4,   5,   7,   9,  11,
c    1               15,  20,  25,  32,  40,  50,  65,  85,
c    2              105, 130, 170, 220, 250, 280, 320, 360,
c    3              410, 460, 530, 600, 690, 780, 890,1000/
	data lkurpa/  0,   1,   2,   2,   3,   4,   5,
     1                6,   7,   9,  11,  13,  17,  21,  25,
     2               32,  39,  49,  60,  75,  93, 115, 143,
     3              178, 220, 274, 338, 422, 522, 648, 806,1000/
c
c let's do the lookup (sort of dumb comment really)
c
	if (irpa .eq. 1023) then
	   isclrp=-1
	else
	   do k=1,32
	      kdwn=33-k
	      if (lkurpa(kdwn) .le. irpa) go to 100
	   end do
  100	   continue
	   isclrp=kdwn
	end if
c
c
	return
	end