function findvalue(ix,n,ain,indxa)!----------------------------------------------------------------------- ! ! Purpose: ! Subroutine for finding ix-th smallest value in the array! The elements are rearranged so that the ix-th smallest! element is in the ix place and all smaller elements are! moved to the elements up to ix (with random order).!! Algorithm: Based on the quicksort algorithm.!! Author:       T. Craig! !-----------------------------------------------------------------------   use precision, only: r8   implicit none!! arguments!   integer, intent(in) :: ix                ! element to search for   integer, intent(in) :: n                 ! total number of elements   integer, intent(inout):: indxa(n)        ! array of integers   real(r8), intent(in) :: ain(n)           ! array to search!   integer findvalue                        ! return value!! local variables!   integer i,j                              ! loop variables   integer ir,il,im                         ! Right, left, and middle index   integer itmp                             ! Index to switch   logical found                            ! If found value!!---------------------------Routine-----------------------------!   found = .false.   il=1   ir=n   do while (.not.found)      if (ir-il <= 1) then         if (ir-il == 1) then            if (ain(indxa(ir)) < ain(indxa(il))) then               call findvalue_swap(indxa(il),indxa(ir))            endif         endif         findvalue=indxa(ix)         found = .true.      else         im=(il+ir)/2         call findvalue_swap(indxa(im),indxa(il+1))         if (ain(indxa(il+1)) > ain(indxa(ir))) then            call findvalue_swap(indxa(il+1),indxa(ir))         endif         if (ain(indxa(il)) > ain(indxa(ir))) then            call findvalue_swap(indxa(il),indxa(ir))         endif         if (ain(indxa(il+1)) > ain(indxa(il))) then            call findvalue_swap(indxa(il),indxa(il+1))         endif         i=il+2         j=ir-1         itmp=indxa(il)         do while (j >= i)            do while (ain(indxa(i)) < ain(itmp))               i=i+1            end do            do while (ain(indxa(j)) > ain(itmp))               j=j-1            end do            if (j >= i) then              call findvalue_swap(indxa(i),indxa(j))            endif         end do         indxa(il)=indxa(j)         indxa(j)=itmp         if (j >= ix) ir=j-1         if (j <= ix) il=i      endif   end do   returnend function findvaluesubroutine findvalue_swap(k1,k2)!----------------------------------------------------------------------- ! ! Purpose: ! Simple subroutine to swap two integer values!! Author:       T. Craig! !-----------------------------------------------------------------------   implicit none   integer k1,k2,ktmp   ktmp = k1   k1=k2   k2=ktmp   returnend subroutine findvalue_swap