;The function edgedetect.pro is a crude square wavelet
;edgedetector. It was designed to be used in conjuction with
;speccorrec_ift.pro to find the 'knee' where noise starts to be
;noticable in the h2o vapor spectra from wlef trailer licors.
;Use is as follows:
;                ans=edgedetect(x,a)
;Where
; input |         x = input signal to find edge in
;       |         a = width of wavelet (must be odd #)
;
;       |    ans(0) = non-normalized area under curve created by 
;output |             mulitiplying wavelet by signal over width of wavelet
;       |             (by non-normalized, I mean just the sum of the
;       |             discrete values under the curve)
;       |    ans(1) = an index vector starting at index of x where
;       |             center of wavelet lies when the wavelet is at
;       |             left-most position.
;
;BWBerger 4/20/99

function edgedetect,x,a

n=len(x)

ev=2*floor(a/2.)
if a eq ev then begin
   a=a+1
   print, 'a needs to be odd. One added. a=', a
endif

wav=fltarr(1,n-a+1)

for i=0,n-a do begin
   wav(i)=total(x(i:i+(a+1)/2-1-1))-total(x(i+(a+1)/2+1-1:i+a-1))
endfor

t=findgen(1,n-a+1)+(a-1)/2

ans=[wav,t]

return,ans
end