--- ray/src/gen/genbranch.c	1991/11/12 17:04:47	2.1
+++ ray/src/gen/genbranch.c	1993/08/02 14:23:00	2.4
@@ -12,6 +12,8 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #include  <stdio.h>
 
+#include  <math.h>
+
 #include  "random.h"
 
 #define  errf()		(var*(0.5-frandom()))
@@ -30,12 +32,15 @@ int  rdepth = 3;			/* recursion depth */
 
 double  var = 0.3;			/* variability */
 
+#ifdef  DCL_ATOF
+extern double  atof();
+#endif
 
+
 main(argc, argv)
 int  argc;
 char  *argv[];
 {
-	double  atof();
 	int  i, j;
 
 	for (i = 1; i < argc && argv[i][0] == '-'; i++)