From 00ca493860ead25b6e9c2629f133fdfaf16f5cec Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Wed, 27 May 2015 18:22:27 +1000
Subject: [PATCH] AP_AHRS: prevent a floating exception in update_trig

---
 libraries/AP_AHRS/AP_AHRS.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/libraries/AP_AHRS/AP_AHRS.cpp b/libraries/AP_AHRS/AP_AHRS.cpp
index d86d93dbe7..aab7dee011 100644
--- a/libraries/AP_AHRS/AP_AHRS.cpp
+++ b/libraries/AP_AHRS/AP_AHRS.cpp
@@ -255,7 +255,11 @@ void AP_AHRS::update_trig(void)
 
     // sin_roll, sin_pitch
     _sin_pitch = -temp.c.x;
-    _sin_roll = temp.c.y / _cos_pitch;
+    if (is_zero(_cos_pitch)) {
+        _sin_roll = sinf(roll);
+    } else {
+        _sin_roll = temp.c.y / _cos_pitch;
+    }
 
     // sanity checks
     if (yaw_vector.is_inf() || yaw_vector.is_nan()) {