fix [3452750] Issue 14634: SensorManager.getRotationMatrixFromVector gets NaN-Values [external] [DO NOT MERGE]

pixelflinger · pixelflinger · commit 5f94c315a655 · 2011-03-07T17:58:56.000-08:00
make sure to not pass negative numbers to sqrt().

Change-Id: Ia31f7ebb7b75c79b548e428c6084fa55031617d0
related-bug: 3452750
diff --git a/core/java/android/hardware/SensorManager.java b/core/java/android/hardware/SensorManager.java
@@ -1970,7 +1970,8 @@ public static void getRotationMatrixFromVector(float[] R, float[] rotationVector
         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;

Original file line number	Diff line number	Diff line change
`@@ -1970,7 +1970,8 @@ public static void getRotationMatrixFromVector(float[] R, float[] rotationVector`
`1970`	`1970`	`if (rotationVector.length == 4) {`
`1971`	`1971`	`q0 = rotationVector[3];`
`1972`	`1972`	`} else {`
`1973`		`- q0 = (float)Math.sqrt(1 - q1q1 - q2q2 - q3*q3);`
	`1973`	`+ q0 = 1 - q1q1 - q2q2 - q3*q3;`
	`1974`	`+ q0 = (q0 > 0) ? (float)Math.sqrt(q0) : 0;`
`1974`	`1975`	`}`
`1975`	`1976`
`1976`	`1977`	`float sq_q1 = 2 * q1 * q1;`