pro ccm_UNRED, wave, flux, ebv, funred, R_V = r_v

 On_error, 2

 if N_params() LT 3 then begin
     print,'Syntax: CCM_UNRED, wave, flux, ebv, funred,[ R_V = ]'
     return
 endif

 if not keyword_set(R_V) then R_V = 3.1

 x = 10000./ wave                ; Convert to inverse microns 
 npts = N_elements( x )
 a = fltarr(npts)  
 b = fltarr(npts)
;******************************

 good = where( (x GT 0.3) and (x  LT 1.1), Ngood )       ;Infrared
 if Ngood GT 0 then begin
      a[good] =  0.574 * x[good]^(1.61)
      b[good] = -0.527 * x[good]^(1.61)
 endif

;******************************

 good = where( (x GE 1.1) and (x LT 3.3) ,Ngood)           ;Optical/NIR
 if Ngood GT 0 then begin             ;Use new constants from O'Donnell (1994)
     y = x[good] - 1.82
;     c1 = [ 1. , 0.17699, -0.50447, -0.02427,  0.72085,    $ ;Original
;                 0.01979, -0.77530,  0.32999 ]               ;coefficients
;     c2 = [ 0.,  1.41338,  2.28305,  1.07233, -5.38434,    $ ;from CCM89
;                -0.62251,  5.30260, -2.09002 ]
      c1 = [ 1. , 0.104,   -0.609,    0.701,  1.137,    $    ;New coefficients
                 -1.718,   -0.827,    1.647, -0.505 ]        ;from O'Donnell
      c2 = [ 0.,  1.952,    2.908,   -3.989, -7.985,    $    ;(1994)
                 11.102,    5.491,  -10.805,  3.347 ]

     a[good] = poly( y, c1)
     b[good] = poly( y, c2)
 endif
;******************************

 good = where( (x GE 3.3) and (x LT 8) ,Ngood)           ;Mid-UV
 if Ngood GT 0 then begin

    y = x[good]
    F_a = fltarr(Ngood)    & F_b = fltarr(Ngood)
    good1 = where( (y GT 5.9), Ngood1 )
    if Ngood1 GT 0 then begin
       y1 = y[good1] - 5.9
       F_a[ good1] = -0.04473 * y1^2 - 0.009779 * y1^3
       F_b[ good1] =   0.2130 * y1^2  +  0.1207 * y1^3
    endif
    
   a[good] =  1.752 - 0.316*y - (0.104 / ( (y-4.67)^2 + 0.341 )) + F_a
   b[good] = -3.090 + 1.825*y + (1.206 / ( (y-4.62)^2 + 0.263 )) + F_b
 endif

;   *******************************

 good = where( (x GE 8) and (x LE 11), Ngood )         ;Far-UV
 if Ngood GT 0 then begin
    y = x[good] - 8.
    c1 = [ -1.073, -0.628,  0.137, -0.070 ]
    c2 = [ 13.670,  4.257, -0.420,  0.374 ]
    a[good] = poly(y, c1)
    b[good] = poly(y, c2)
 endif

;   *******************************

; Now apply extinction correction to input flux vector

  A_V = R_V * EBV
  A_lambda = A_V * (a + b/R_V)
  if N_params() EQ 3 then flux = flux * 10.^(0.4*A_lambda) else $
        funred = flux * 10.^(0.4*A_lambda)       ;Derive unreddened flux

 return     
 end