1 files changed, 81 insertions, 0 deletions
diff --git a/noao/onedspec/sensfunc/sfshift.x b/noao/onedspec/sensfunc/sfshift.x
new file mode 100644
index 00000000..07b204f3
--- /dev/null
+++ b/noao/onedspec/sensfunc/sfshift.x
@@ -0,0 +1,81 @@
+include	"sensfunc.h"
+
+
+# SF_SHIFT -- Shift or unshift all standard stars to have zero mean residual.
+
+procedure sf_shift (stds, nstds, flag)
+
+pointer	stds[nstds]		# Standard star data
+int	nstds			# Number of standard stars
+int	flag			# Shift flag
+
+pointer	x, y, w, f
+int	i, j, n, nshift
+real	shift, shift1, minshift
+
+begin
+	# If flag is YES then unshift the data.
+	if (flag == YES) {
+	    do i = 1, nstds {
+	        if (STD_FLAG(stds[i]) == SF_EXCLUDE)
+		    next
+	        n = STD_NWAVES(stds[i])
+	        if (n == 0)
+		    next
+	        y = STD_SENS(stds[i])
+	        call asubkr (Memr[y], STD_SHIFT(stds[i]), Memr[y], n)
+	        STD_SHIFT(stds[i]) = 0.
+	    }
+	    flag = NO
+	    call printf ("Data unshifted")
+	    return
+	}
+
+	# Determine the shifts needed to make the mean residual zero.
+	# Also determine the minimum shift.
+
+	minshift = 0.
+	do i = 1, nstds {
+	    if (STD_FLAG(stds[i]) == SF_EXCLUDE)
+		next
+	    n = STD_NWAVES(stds[i])
+	    if (n == 0)
+		next
+	    x = STD_WAVES(stds[i])
+	    y = STD_SENS(stds[i])
+	    w = STD_WTS(stds[i])
+	    f = STD_FIT(stds[i])
+	    nshift = 0
+	    shift = 0.
+	    shift1 = 0.
+	    do j = 1, n {
+		shift1 = shift1 + Memr[f+j-1] - Memr[y+j-1]
+		if (Memr[w+j-1] > 0.) {
+		    shift = shift + Memr[f+j-1] - Memr[y+j-1]
+		    nshift = nshift + 1
+		}
+	    }
+	    if (nshift > 0) {
+		shift = STD_SHIFT(stds[i]) + shift / nshift
+		if (shift < minshift)
+		    minshift = shift
+	    } else
+		shift = STD_SHIFT(stds[i]) + shift1 / n
+	    STD_SHIFT(stds[i]) = shift
+	}
+
+	# Adjust the shifts to be upwards.
+	do i = 1, nstds {
+	    if (STD_FLAG(stds[i]) == SF_EXCLUDE)
+		next
+	    n = STD_NWAVES(stds[i])
+	    if (n == 0)
+		next
+	    y = STD_SENS(stds[i])
+	    shift = STD_SHIFT(stds[i]) - minshift
+	    call aaddkr (Memr[y], shift, Memr[y], n)
+	    STD_SHIFT(stds[i]) = shift
+	}
+	flag = YES
+	call printf ("Data shifted")
+end