Initial commit

1 files changed, 45 insertions, 0 deletions

diff --git a/math/gsurfit/gsgcoeffd.x b/math/gsurfit/gsgcoeffd.x
new file mode 100644
index 00000000..32dead75
--- /dev/null
+++ b/math/gsurfit/gsgcoeffd.x
@@ -0,0 +1,45 @@
+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+include <math/gsurfit.h>
+include "dgsurfitdef.h"
+
+# GSGCOEFF -- Procedure to fetch a particular coefficient.
+# If the requested coefficient is undefined then INDEF is returned.
+
+double procedure dgsgcoeff (sf, xorder, yorder)
+
+pointer	sf		# pointer to the surface fitting descriptor
+int	xorder		# X order of desired coefficent
+int	yorder		# Y order of desired coefficent
+
+int	i, n, maxorder, xincr
+
+begin
+	if ((xorder > GS_XORDER(sf)) || (yorder > GS_YORDER(sf)))
+	    return (INDEFD)
+
+	switch (GS_XTERMS(sf)) {
+	case GS_XNONE:
+	    if (yorder == 1)
+		n = xorder
+	    else if (xorder == 1)
+		n = GS_NXCOEFF(sf) + yorder - 1
+	    else
+		return (INDEFD)
+	case GS_XHALF:
+	    maxorder = max (GS_XORDER(sf) + 1, GS_YORDER(sf) + 1)
+	    if ((xorder + yorder) > maxorder)
+		return (INDEFD)
+	    n = xorder
+	    xincr = GS_XORDER(sf)
+	    do i = 2, yorder {
+		n = n + xincr
+		if ((i + GS_XORDER(sf) + 1) > maxorder)
+		    xincr = xincr - 1
+	    }
+	case GS_XFULL:
+	    n = xorder + (yorder - 1) * GS_NXCOEFF(sf)
+	}
+
+	return (COEFF(GS_COEFF(sf) + n - 1))
+end