1 files changed, 16 insertions, 0 deletions
diff --git a/src/adjlon.c b/src/adjlon.c
new file mode 100644
index 00000000..3de12a16
--- /dev/null
+++ b/src/adjlon.c
@@ -0,0 +1,16 @@
+/* reduce argument to range +/- PI */
+#ifndef lint
+static const char SCCSID[]="@(#)adjlon.c	4.3	93/06/12	GIE	REL";
+#endif
+#include <math.h>
+/* note: PI adjusted high
+** approx. true val:	3.14159265358979323844
+*/
+#define SPI		3.14159265359
+#define TWOPI	6.2831853071795864769
+	double
+adjlon (double lon) {
+	while ( fabs(lon) > SPI )
+		lon += lon < 0. ? TWOPI : -TWOPI;
+	return( lon );
+}