From 5f94c315a65569bf66d603227177ba3f5ba5acd4 Mon Sep 17 00:00:00 2001
From: Mathias Agopian <mathias@google.com>
Date: Mon, 14 Feb 2011 16:34:07 -0800
Subject: fix [3452750] Issue 14634: SensorManager.getRotationMatrixFromVector
 gets NaN-Values [external] [DO NOT MERGE]

make sure to not pass negative numbers to sqrt().

Change-Id: Ia31f7ebb7b75c79b548e428c6084fa55031617d0
related-bug: 3452750
---
 core/java/android/hardware/SensorManager.java | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/core/java/android/hardware/SensorManager.java b/core/java/android/hardware/SensorManager.java
index cc82170..b1a9349 100644
--- a/core/java/android/hardware/SensorManager.java
+++ b/core/java/android/hardware/SensorManager.java
@@ -1970,7 +1970,8 @@ public class SensorManager
         if (rotationVector.length == 4) {
             q0 = rotationVector[3];
         } else {
-            q0 = (float)Math.sqrt(1 - q1*q1 - q2*q2 - q3*q3);
+            q0 = 1 - q1*q1 - q2*q2 - q3*q3;
+            q0 = (q0 > 0) ? (float)Math.sqrt(q0) : 0;
         }
 
         float sq_q1 = 2 * q1 * q1;
-- 
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