--- ray/src/common/calexpr.c	2019/03/04 18:16:18	2.37
+++ ray/src/common/calexpr.c	2019/12/28 18:05:13	2.39
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: calexpr.c,v 2.37 2019/03/04 18:16:18 greg Exp $";
+static const char	RCSid[] = "$Id: calexpr.c,v 2.39 2019/12/28 18:05:13 greg Exp $";
 #endif
 /*
  *  Compute data values using expression parser
@@ -19,8 +19,6 @@ static const char	RCSid[] = "$Id: calexpr.c,v 2.37 201
 
 #include "copyright.h"
 
-#include  <stdio.h>
-#include  <string.h>
 #include  <ctype.h>
 #include  <errno.h>
 #include  <math.h>
@@ -105,10 +103,13 @@ eval(			/* evaluate an expression string */
     char  *expr
 )
 {
+    int  prev_support = esupport;
     EPNODE  *ep;
     double  rval;
 
+    esupport &= ~E_RCONST;	/* don't bother reducing constant expr */
     ep = eparse(expr);
+    esupport = prev_support;	/* as you were */
     rval = evalue(ep);
     epfree(ep);
     return(rval);