1 files changed, 52 insertions, 0 deletions
diff --git a/sys/vops/lz/amedx.x b/sys/vops/lz/amedx.x
new file mode 100644
index 00000000..ca2b75dc
--- /dev/null
+++ b/sys/vops/lz/amedx.x
@@ -0,0 +1,52 @@
+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+# AMED -- Vector median selection.  The selection is carried out in a temporary
+# array, leaving the input vector unmodified.  Especially demanding applications
+# may wish to call the asok routine directory to avoid the call to the memory
+# allocator.
+
+complex procedure amedx (a, npix)
+
+complex	a[ARB]
+int	npix
+
+pointer	sp, aa
+complex	median
+complex	asokx()		# select the Kth smallest element from A
+real	a1, a2, a3
+
+begin
+	switch (npix) {
+	case 1, 2:
+	    return (a[1])
+
+	case 3:
+		a1 = abs (a[1])
+		a2 = abs (a[2])
+		a3 = abs (a[3])
+		if (a1 < a2) {
+		    if (a2 < a3)
+			return (a[2])
+		    else if (a1 < a3)
+			return (a[3])
+		    else
+			return (a[1])
+		} else {
+		    if (a2 > a3)
+			return (a[2])
+		    else if (a1 < a3)
+			return (a[1])
+		    else
+			return (a[3])
+		}
+
+	default:
+	    call smark (sp)
+	    call salloc (aa, npix, TY_COMPLEX)
+	    call amovx (a, Memx[aa], npix)
+	    median = asokx (Memx[aa], npix, (npix + 1) / 2)
+	    call sfree (sp)
+
+	    return (median)
+	}
+end