--- ray/src/common/calprnt.c	2003/02/25 02:47:21	2.3
+++ ray/src/common/calprnt.c	2024/02/24 19:00:23	2.9
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: calprnt.c,v 2.3 2003/02/25 02:47:21 greg Exp $";
+static const char	RCSid[] = "$Id: calprnt.c,v 2.9 2024/02/24 19:00:23 greg Exp $";
 #endif
 /*
  *  calprint.c - routines for printing calcomp expressions.
@@ -8,19 +8,43 @@ static const char	RCSid[] = "$Id: calprnt.c,v 2.3 2003
 #include "copyright.h"
 
 #include  <stdio.h>
+#include  <string.h>
 
+#include  "rterror.h"
 #include  "calcomp.h"
 
 
+/* is child operation lower precedence than parent? */
+static int
+lower_precedent_op(int typ, EPNODE *ek)
+{
+    if (ek == NULL)
+	return(0);
+    switch (typ) {
+	case '+':
+		return(0);
+	case '-':
+		return(ek->type == '+');
+	case '*':
+		return(strchr("+-", ek->type) != NULL);
+	case '/':
+		return(strchr("+-*", ek->type) != NULL);
+	case '^':
+		return(strchr("+-*/^", ek->type) != NULL);
+	}
+    return(0);			/* child not binary op */
+}
+
 void
-eprint(ep, fp)			/* print a parse tree */
-register EPNODE  *ep;
-FILE  *fp;
+eprint(				/* print a parse tree */
+	EPNODE  *ep,
+	FILE  *fp
+)
 {
     static EPNODE  *curdef = NULL;
-    register EPNODE  *ep1;
+    EPNODE  *ep1 = NULL;
 
-    switch (ep->type) {
+    switch (ep==NULL ? -1 : ep->type) {
 
 	case VAR:
 	    fputs(ep->v.ln->name, fp);
@@ -55,11 +79,6 @@ FILE  *fp;
 	    fprintf(fp, "%.9g", ep->v.num);
 	    break;
 
-	case UMINUS:
-	    fputc('-', fp);
-	    eprint(ep->v.kid, fp);
-	    break;
-
 	case CHAN:
 	    fprintf(fp, "$%d", ep->v.chan);
 	    break;
@@ -75,19 +94,42 @@ FILE  *fp;
 	    eprint(ep->v.kid->sibling, fp);
 	    curdef = ep1;
 	    break;
-	    
+
+	case UMINUS:
+	    fputc('-', fp);
+	    if (ep->v.kid != NULL && strchr("+-*/^", ep->v.kid->type)) {
+		fputc('(', fp);
+		eprint(ep->v.kid, fp);
+		fputc(')', fp);
+	    } else
+		eprint(ep->v.kid, fp);
+	    break;
+
 	case '+':
-	case '-':
 	case '*':
+	case '-':
 	case '/':
 	case '^':
-	    fputc('(', fp);
-	    eprint(ep->v.kid, fp);
-	    fputc(' ', fp);
-	    fputc(ep->type, fp);
-	    fputc(' ', fp);
-	    eprint(ep->v.kid->sibling, fp);
-	    fputc(')', fp);
+	    if (lower_precedent_op(ep->type, ep->v.kid)) {
+		fputc('(', fp);
+		eprint(ep->v.kid, fp);
+		fputc(')', fp);
+	    } else
+		eprint(ep->v.kid, fp);
+	    for (ep1 = ep->v.kid->sibling; ep1 != NULL; ep1 = ep1->sibling) {
+	    	if (ep->type != '^') {
+		    fputc(' ', fp);
+		    fputc(ep->type, fp);
+		    fputc(' ', fp);
+	    	} else
+		    fputc(ep->type, fp);
+		if (lower_precedent_op(ep->type, ep1)) {
+		    fputc('(', fp);
+		    eprint(ep1, fp);
+		    fputc(')', fp);
+	    	} else
+		    eprint(ep1, fp);
+	    }
 	    break;
 
 	default:
@@ -95,16 +137,16 @@ FILE  *fp;
 	    quit(1);
 
     }
-
 }
 
 
 void
-dprint(name, fp)		/* print a definition (all if no name) */
-char  *name;
-FILE  *fp;
+dprint(			/* print a definition (all if no name) */
+	char  *name,
+	FILE  *fp
+)
 {
-    register EPNODE  *ep;
+    EPNODE  *ep;
     
     if (name == NULL)
 	for (ep = dfirst(); ep != NULL; ep = dnext()) {