function getindex2,file,wave_in

;-----------------------------------------------------------------
; This routine interpolates refractive indices in wavelength,
; from a specified file of indices.
;
; The data whould be in 3 columns:
;    wavelength,  imaginary index,  real index
;
; input:
;    file......file containing the refractive index data (wave, real, imag)
;    wave_in...input wavelength, units as in file (microns or 1/cm)
;
; output:
;    result...complex refractive index
;
; source: Mark Hervig (UWyo)
;-----------------------------------------------------------------

   maxwave = 4000             ; max # wavelengths
   wave    = fltarr(maxwave)  ; wavelength,  microns
   dxr     = fltarr(maxwave)  ; real index
   dxi     = fltarr(maxwave)  ; imaginary index
   headr   = ' '
   i       = 0

;- read the index file

   openr,lu,file,/get_lun

   readf,lu,headr ; print,headr
   readf,lu,headr ; print,headr
   readf,lu,headr ; print,headr

   while (not eof(lu)) do begin
     readf,lu,a,b,c
     wave(i) = a
     dxr(i)  = c
     dxi(i)  = b
     i=i+1
     if (i eq maxwave) then $
       stop,'exceeded max # wavelengths in getindex.pro'
   endwhile

   nw = i-1
   wave = wave(0:nw-1)
   dxr  = dxr(0:nw-1)
   dxi  = dxi(0:nw-1)

   close,lu
   free_lun,lu

;- wave increasing or decreasing?

   if (wave(0) lt wave(1)) then begin
     st = 0 & en = nw-1 & inc = 1
   endif

   if (wave(0) gt wave(1)) then begin
     st = nw-1 & en = 0 & inc = -1
   endif

;- interpolate index to wave_in

   result = complex(0.0,0.0)

   if (wave_in ge wave(st) and wave_in le wave(en) ) then begin

     for i = st,en,inc do begin
       if (wave(i) le wave_in and wave(i+inc) gt wave_in) then begin

         term   = (wave_in-wave(i)) /(wave(i+inc)-wave(i))
         dr     = term * (dxr(i+inc)-dxr(i)) + dxr(i)
         di     = term * (dxi(i+inc)-dxi(i)) + dxi(i)
         result = complex(dr,di)
         goto,jump1

       endif
     endfor

     print  ,wave_in,' not in range in getindex.pro'
     result = complex(0.0,0.0)
   endif

   jump1:

   return,result
   end