pro ltf_plotlog, avg, var, favg, yfit, pmin, pmax, qplot, gainc
;
; procedure to PLOT light transfer for 512 CCD
;
;
!type = 3+16		;log log plot
;
!ignore = -1
!FANCY = 1
!XTITLE = 'Signal - DC_Offset   (DN)'
!YTITLE = '(Photon Noise) !E2!N - Read Noise !E2!N    (DN)!E2!N'
!mtitle = ' '
SET_XY
;
valid=indgen( n_elements(avg) )
if (pmax ne 0.) then valid = where ((avg lt pmax) and (avg gt pmin))

pavg = avg(valid)
pvar = var(valid)
;!psym = 1		; + symbol
!psym = 3		; . symbol

!ymin = 1
!ymax = max(pvar)
!c = 0

plot, pavg, pvar

if (qplot eq 1) then begin
    !PSYM = 0
    OPLOT, favg, yfit

    sout = STRING (gainc, "(' Gain Constant = ',F7.2,' e/DN')")
    plottime, 0.15, 0.70, sout, 0.8
END

return
end