SUBROUTINE locate(xx,n,x,j)
      INTEGER, INTENT(out) :: j
      REAL*8 x,xx(n)
      INTEGER jl,jm,ju,n
      jl=0
      ju=n+1

10    if(ju-jl.gt.1)then
        jm=(ju+jl)/2
        if((xx(n).ge.xx(1)).eqv.(x.ge.xx(jm)))then
          jl=jm
        else
          ju=jm
        endif
      goto 10
      endif

      if(x.eq.xx(1))then
        j=1
      else if(x.eq.xx(n))then
        j=n-1
      else
        j=jl
      endif
      return
      END

function CDF_lambda(no_target, temp) result(lambda)
implicit none
  integer(I2B), intent(in) :: no_target
  real(BW),intent(in) :: temp
real(BW) :: rand, dy
integer(I2B) :: jlo, N_interp_points, min_index, N_points_table, n1, n2
real(BW), allocatable :: CDFtable(:)


N_points_table= 1000
N_interp_points=2 !2 for linear interpolation
jlo=0
CALL RANDOM_NUMBER(rand)

!first find the right two temperatures, then find the right rows, then interpolate
n1=int((temp-100)/50)+1
n2=n1+1
allocate(CDFtable(N_points_table))
...
!setting the content of CDFtable
...
call locate(CDFtable,N_points_table,rand,jlo)
....
....