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# AP_HGMSUB -- Procedure to subtract a point from an existing histogram.
procedure ap_hgmsub (hgm, nbins, z1, z2, skypix)
real hgm[ARB] # histogram
int nbins # number of bins
real z1, z2 # range of histogram
real skypix # sky value
int bin
real dh
begin
if (skypix < z1 || skypix > z2)
return
dh = real (nbins - 1) / (z2 - z1)
bin = int ((skypix - z1) * dh) + 1
hgm[bin] = hgm[bin] - 1.0
end
# AP_HGMSUB2 -- Procedure to subract points from the accumulated sums
# and the existing histogram.
procedure ap_hgmsub2 (hgm, nbins, z1, z2, skypix, sky_zero, sumpx, sumsqpx,
sumcbpx)
real hgm[ARB] # histogram
int nbins # number of bins
real z1, z2 # range of histogram
real skypix # sky value
real sky_zero # sky zero point for moment analysis
double sumpx # sum of the sky pixel values
double sumsqpx # sum of the squares of the sky pixel values
double sumcbpx # sum of the cubes of the sky pixel values
double dsky
int bin
real dh
begin
if (skypix < z1 || skypix > z2)
return
dsky = skypix - sky_zero
sumpx = sumpx - dsky
sumsqpx = sumsqpx - dsky ** 2
sumcbpx = sumcbpx - dsky ** 3
dh = real (nbins - 1) / (z2 - z1)
bin = int ((skypix - z1) * dh) + 1
hgm[bin] = hgm[bin] - 1.0
end
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