1 files changed, 44 insertions, 0 deletions
diff --git a/noao/onedspec/ecidentify/ecdoshift.x b/noao/onedspec/ecidentify/ecdoshift.x
new file mode 100644
index 00000000..1689bc92
--- /dev/null
+++ b/noao/onedspec/ecidentify/ecdoshift.x
@@ -0,0 +1,44 @@
+include	"ecidentify.h"
+
+# EC_DOSHIFT -- Minimize residuals by constant shift.
+
+procedure ec_doshift (ec, interactive)
+
+pointer	ec			# ID pointer
+int	interactive		# Called interactively?
+
+int	i, j
+double	shft, delta, rms, ec_fitpt(), ecf_getd()
+
+begin
+	shft = 0.
+	rms = 0.
+	j = 0
+	for (i=1; i <= EC_NFEATURES(ec); i = i + 1) {
+	    if (IS_INDEFD (USER(ec,i)))
+		next
+	    delta = USER(ec,i) - ec_fitpt (ec, APN(ec,i), PIX(ec,i))
+	    delta = delta * ORDER(ec,i)
+	    shft = shft + delta
+	    rms = rms + delta * delta
+	    j = j + 1
+	}
+
+	if (j > 0) {
+	    shft = shft / j
+	    rms = rms / j
+	    if (interactive == YES) {
+		i = EC_ORDER(ec)
+	        call printf ("Coordinate shift=%5f, rms=%5f")
+		    call pargd (shft / i)
+		    if (j == 1)
+			call pargd (INDEFD)
+		    else
+		        call pargd (sqrt (rms - shft ** 2) / i)
+	    }
+	    shft = shft + ecf_getd ("shift")
+	    call ecf_setd ("shift", shft)
+	    EC_NEWECF(ec) = YES
+	    EC_NEWGRAPH(ec) = YES
+	}
+end