pro tmatrix_idl_call2,wave,index,rad,ar, ex,sc,ab

;----------------------------------------------------------------------------------
; Feed data into the fortran tmatrix routine
;
; Input (all scalars):
;   wave......wavelength (microns)
;   index.....complex refractive index
;   rad.......particle radius (microns)
;   ar........axial ratio (>1 = oblate)
;
; Output:
;   ex.......extinction cross section (microns^2)
;   sc.......scattering cross section (microns^2)
;   ab.......absorption cross section (microns^2)
;
; Source: Mark Hervig
;----------------------------------------------------------------------------------

   ex = 0.0
   sc = 0.0
   ab = 0.0      
   
   if ( float(index) gt 0.0) then begin

   pat = '/users/mhervig/fortlib/t-matrix/'
   
   filei = pat + 'tmatrix_idl_in.txt'
   fileo = pat + 'tmatrix_idl_out.txt'
   
;- Write the input parameters to a file as input for "tmatrix_idl.f"
   
   openw,lu,filei,/get_lun
     
     printf,lu,format='(5e15.6)', wave,float(index),imaginary(index),rad,ar

   close,lu
   free_lun,lu
   
;- Run the Tmatrix fortran

   spawn,pat + 'tmatrix_idl'
   
;- Read the file written by the Tmatrix fortran 
   
   openr,lu,fileo,/get_lun
     
     readf,lu,ex,sc

   close,lu
   free_lun,lu
   
   ab = ex - sc
   
   endif
   
;- done

   end