Import sources from 2011-03-30 iso image

1 files changed, 24 insertions, 0 deletions

diff --git a/sys/src/libc/port/atan2.c b/sys/src/libc/port/atan2.c
new file mode 100755
index 000000000..480eb4c67
--- /dev/null
+++ b/sys/src/libc/port/atan2.c
@@ -0,0 +1,24 @@
+#include <u.h>
+#include <libc.h>
+/*
+	atan2 discovers what quadrant the angle
+	is in and calls atan.
+*/
+
+double
+atan2(double arg1, double arg2)
+{
+
+	if(arg1+arg2 == arg1) {
+		if(arg1 >= 0)
+			return PIO2;
+		return -PIO2;
+	}
+	arg1 = atan(arg1/arg2);
+	if(arg2 < 0) {
+		if(arg1 <= 0)
+			return arg1 + PI;
+		return arg1 - PI;
+	}
+	return arg1;
+}