1 files changed, 81 insertions, 0 deletions
diff --git a/nuttx/lib/math/lib_atan2f.c b/nuttx/lib/math/lib_atan2f.c
new file mode 100644
index 000000000..a60d32c65
--- /dev/null
+++ b/nuttx/lib/math/lib_atan2f.c
@@ -0,0 +1,81 @@
+/************************************************************************
+ * lib/math/lib_atan2f.c
+ *
+ * This file is a part of NuttX:
+ *
+ *   Copyright (C) 2012 Gregory Nutt. All rights reserved.
+ *   Ported by: Darcy Gong
+ *
+ * It derives from the Rhombs OS math library by Nick Johnson which has
+ * a compatibile, MIT-style license:
+ *
+ * Copyright (C) 2009-2011 Nick Johnson <nickbjohnson4224 at gmail.com>
+ * 
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ ************************************************************************/
+
+/************************************************************************
+ * Included Files
+ ************************************************************************/
+
+#include <math.h>
+
+/************************************************************************
+ * Public Functions
+ ************************************************************************/
+
+float atan2f(float y, float x)
+{
+  if (y == 0.0)
+    {
+      if (x >= 0.0)
+        {
+          return 0.0;
+        }
+      else
+        {
+          return M_PI;
+        }
+    }
+  else if (y > 0.0)
+    {
+      if (x == 0.0)
+        {
+          return M_PI_2;
+        }
+      else if (x > 0.0)
+        {
+          return atanf(y / x);
+        }
+      else
+        {
+          return M_PI - atanf(y / x);
+        }
+    }
+  else
+    {
+      if (x == 0.0)
+        {
+          return M_PI + M_PI_2;
+        }
+      else if (x > 0.0)
+        {
+          return 2 * M_PI - atanf(y / x);
+        }
+      else
+        {
+          return M_PI + atanf(y / x);
+        }
+    }
+}