--- ray/src/util/rsensor.c	2013/10/16 04:35:50	2.13
+++ ray/src/util/rsensor.c	2015/04/23 23:34:18	2.15
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: rsensor.c,v 2.13 2013/10/16 04:35:50 greg Exp $";
+static const char RCSid[] = "$Id: rsensor.c,v 2.15 2015/04/23 23:34:18 greg Exp $";
 #endif
 
 /*
@@ -15,7 +15,7 @@ static const char RCSid[] = "$Id: rsensor.c,v 2.13 201
 
 #define DEGREE		(PI/180.)
 
-#define	MAXNT		180	/* maximum number of theta divisions */
+#define	MAXNT		181	/* maximum number of theta divisions */
 #define MAXNP		360	/* maximum number of phi divisions */
 
 extern char	*progname;	/* global argv[0] */
@@ -398,9 +398,8 @@ init_ptable(
 		tvals[i] = 1. - ( (1.-frac)*cos(thdiv[t]) +
 						frac*cos(thdiv[t+1]) );
 				/* offset b/c sensor values are centered */
-		if ((t < sntp[0]-1) & (frac >= 0.5)) {
-			if ((frac -= 0.5) < 0)
-				frac = 0;
+		if ((t < sntp[0]-1) & (!t | (frac >= 0.5))) {
+			frac -= 0.5;
 		} else {
 			frac += 0.5;
 			--t;
@@ -425,6 +424,9 @@ init_ptable(
 		}
 		pvals[i*(nphi+1) + nphi] = phdiv[sntp[1]];
 	}
+						/* duplicate final row */
+	memcpy(pvals+ntheta*(nphi+1), pvals+(ntheta-1)*(nphi+1),
+				sizeof(*pvals)*(nphi+1));
 	tvals[0] = .0f;
 	tvals[ntheta] = (float)tsize;
 }