--- ray/src/cal/cal/sun.cal	2019/11/07 23:15:06	1.3
+++ ray/src/cal/cal/sun.cal	2019/11/08 22:48:08	1.4
@@ -1,4 +1,4 @@
-{ RCSid $Id: sun.cal,v 1.3 2019/11/07 23:15:06 greg Exp $ }
+{ RCSid $Id: sun.cal,v 1.4 2019/11/08 22:48:08 greg Exp $ }
 {*
  *           SOLAR CALCULATIONS
  *
@@ -7,11 +7,13 @@
  *
  *}
 
+DEG : PI/180;
+
 RLAT = 0.66;		{* Site latitude (radians) *}
 
 RLON = 2.13;		{* Site longitude (radians) *}
 
-RSM = 120 * PI/180;	{* Standard meridian (radians) *}
+RSM = 120 * DEG;	{* Standard meridian (radians) *}
 
 
 stadj(jd)		{* solar time adjustment (hours) *}
@@ -34,25 +36,27 @@ salt(sd, st)		{* solar altitude (radians) *}
 { sd is solar declination, st is solar time (hours) }
 =
  asin( sin(RLAT) * sin(sd) - cos(RLAT) * cos(sd) *
-                                     cos(st*PI/12) )
+                                     cos(PI/12*st) )
 ;
 
 
 sazi(sd, st)		{* the solar azimuth (radians) *}
 { sd is solar declination, st is solar time (hours) }
 =
- -atan2( cos(sd) * sin(st*PI/12),
+ -atan2( cos(sd) * sin(PI/12*st),
  	-cos(RLAT)*sin(sd) -
-	sin(RLAT)*cos(sd)*cos(st*PI/12) )
+	sin(RLAT)*cos(sd)*cos(PI/12*st) )
 ;
 
 
-SAZI = sazi(SDEC, STIME) * 180/PI;
+SAZI = sazi(SDEC, STIME) / DEG;
 
-SALT = salt(SDEC, STIME) * 180/PI;
+SALT = salt(SDEC, STIME) / DEG;
 
 SDEC = sdec(JDATE);
 
 STIME = TIME + stadj(JDATE);
+
+HALFDAY = acos(-tan(RLAT)*tan(SDEC)) * (12/PI);
 
 JDATE = DAY + select(MONTH,0,31,59,90,120,151,181,212,243,273,304,334);