Updated the SDK with the latest code from the TF and HL2 branches.

mp/src/mathlib/mathlib_base.cpp

@@ -1461,7 +1461,9 @@ float Bias( float x, float biasAmt )
 	{
 		lastExponent = log( biasAmt ) * -1.4427f; // (-1.4427 = 1 / log(0.5))
 	}
-	return pow( x, lastExponent );
+	float fRet = pow( x, lastExponent );
+	Assert ( !IS_NAN( fRet ) );
+	return fRet;
 }
 
 
@@ -1477,7 +1479,9 @@ float Gain( float x, float biasAmt )
 
 float SmoothCurve( float x )
 {
-	return (1 - cos( x * M_PI )) * 0.5f;
+	// Actual smooth curve. Visualization:
+	// http://www.wolframalpha.com/input/?i=plot%5B+0.5+*+%281+-+cos%5B2+*+pi+*+x%5D%29+for+x+%3D+%280%2C+1%29+%5D
+	return 0.5f * (1 - cos( 2.0f * M_PI * x ) );
 }
 
 
@@ -1856,7 +1860,10 @@ void QuaternionMult( const Quaternion &p, const Quaternion &q, Quaternion &qt )
 
 void QuaternionMatrix( const Quaternion &q, const Vector &pos, matrix3x4_t& matrix )
 {
-	Assert( pos.IsValid() );
+	if ( !HushAsserts() )
+	{
+		Assert( pos.IsValid() );
+	}
 
 	QuaternionMatrix( q, matrix );
 
@@ -1868,7 +1875,10 @@ void QuaternionMatrix( const Quaternion &q, const Vector &pos, matrix3x4_t& matr
 void QuaternionMatrix( const Quaternion &q, matrix3x4_t& matrix )
 {
 	Assert( s_bMathlibInitialized );
-	Assert( q.IsValid() );
+	if ( !HushAsserts() )
+	{
+		Assert( q.IsValid() );
+	}
 
 #ifdef _VPROF_MATHLIB
 	VPROF_BUDGET( "QuaternionMatrix", "Mathlib" );