1 files changed, 47 insertions, 0 deletions
diff --git a/noao/twodspec/apextract/apcvset.x b/noao/twodspec/apextract/apcvset.x
new file mode 100644
index 00000000..656187d5
--- /dev/null
+++ b/noao/twodspec/apextract/apcvset.x
@@ -0,0 +1,47 @@
+include	<math/curfit.h>
+include	"apertures.h"
+
+# AP_CVSET -- Set the trace curve.
+# If the input template aperture is NULL then the output trace curve
+# is set to a constant zero otherwise a copy from the input template
+# aperture is made.
+
+procedure ap_cvset (apin, apout)
+
+pointer	apin		# Input template aperture
+pointer	apout		# Output aperture
+
+int	apaxis, dispaxis, ncoeffs
+real	a, b, c[1]
+pointer	sp, coeffs
+
+int	cvstati()
+
+begin
+	if (AP_CV(apout) != NULL)
+	    call cvfree (AP_CV(apout))
+
+	if (apin == NULL) {
+	    # Determine the aperture and alternate axes.
+	    apaxis = AP_AXIS(apout)
+	    dispaxis = mod (apaxis, 2) + 1
+
+	    # Determine the limits over which the curve is defined.
+	    a = AP_CEN(apout, dispaxis) + AP_LOW(apout, dispaxis)
+	    b = AP_CEN(apout, dispaxis) + AP_HIGH(apout, dispaxis)
+	    if (a == b)
+		b = b + 1
+
+	    # Set the curve to a legendre polynomial of order 1 and value 0.
+	    c[1] = 0.
+	    call cvset (AP_CV(apout), LEGENDRE, a, b, c, 1)
+	} else {
+	    # Use a SAVE and RESTORE to copy the CURFIT data.
+	    call smark (sp)
+	    ncoeffs = cvstati (AP_CV(apin), CVNSAVE)
+	    call salloc (coeffs, ncoeffs, TY_REAL)
+	    call cvsave (AP_CV(apin), Memr[coeffs])
+	    call cvrestore (AP_CV(apout), Memr[coeffs])
+	    call sfree (sp)
+	}
+end