Warning, file /education/gcompris/external/qml-box2d/Box2D/Common/b2Math.cpp was not indexed or was modified since last indexation (in which case cross-reference links may be missing, inaccurate or erroneous).

 /*
 * Copyright (c) 2007-2009 Erin Catto http://www.box2d.org
 *
 * This software is provided 'as-is', without any express or implied
 * warranty.  In no event will the authors be held liable for any damages
 * arising from the use of this software.
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 * 1. The origin of this software must not be misrepresented; you must not
 * claim that you wrote the original software. If you use this software
 * in a product, an acknowledgment in the product documentation would be
 * appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 * misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 */
 
 #include <Box2D/Common/b2Math.h>
 
 const b2Vec2 b2Vec2_zero(0.0f, 0.0f);
 
 /// Solve A * x = b, where b is a column vector. This is more efficient
 /// than computing the inverse in one-shot cases.
 b2Vec3 b2Mat33::Solve33(const b2Vec3& b) const
 {
     float32 det = b2Dot(ex, b2Cross(ey, ez));
     if (det != 0.0f)
     {
         det = 1.0f / det;
     }
     b2Vec3 x;
     x.x = det * b2Dot(b, b2Cross(ey, ez));
     x.y = det * b2Dot(ex, b2Cross(b, ez));
     x.z = det * b2Dot(ex, b2Cross(ey, b));
     return x;
 }
 
 /// Solve A * x = b, where b is a column vector. This is more efficient
 /// than computing the inverse in one-shot cases.
 b2Vec2 b2Mat33::Solve22(const b2Vec2& b) const
 {
     float32 a11 = ex.x, a12 = ey.x, a21 = ex.y, a22 = ey.y;
     float32 det = a11 * a22 - a12 * a21;
     if (det != 0.0f)
     {
         det = 1.0f / det;
     }
     b2Vec2 x;
     x.x = det * (a22 * b.x - a12 * b.y);
     x.y = det * (a11 * b.y - a21 * b.x);
     return x;
 }
 
 ///
 void b2Mat33::GetInverse22(b2Mat33* M) const
 {
     float32 a = ex.x, b = ey.x, c = ex.y, d = ey.y;
     float32 det = a * d - b * c;
     if (det != 0.0f)
     {
         det = 1.0f / det;
     }
 
     M->ex.x =  det * d; M->ey.x = -det * b; M->ex.z = 0.0f;
     M->ex.y = -det * c; M->ey.y =  det * a; M->ey.z = 0.0f;
     M->ez.x = 0.0f; M->ez.y = 0.0f; M->ez.z = 0.0f;
 }
 
 /// Returns the zero matrix if singular.
 void b2Mat33::GetSymInverse33(b2Mat33* M) const
 {
     float32 det = b2Dot(ex, b2Cross(ey, ez));
     if (det != 0.0f)
     {
         det = 1.0f / det;
     }
 
     float32 a11 = ex.x, a12 = ey.x, a13 = ez.x;
     float32 a22 = ey.y, a23 = ez.y;
     float32 a33 = ez.z;
 
     M->ex.x = det * (a22 * a33 - a23 * a23);
     M->ex.y = det * (a13 * a23 - a12 * a33);
     M->ex.z = det * (a12 * a23 - a13 * a22);
 
     M->ey.x = M->ex.y;
     M->ey.y = det * (a11 * a33 - a13 * a13);
     M->ey.z = det * (a13 * a12 - a11 * a23);
 
     M->ez.x = M->ex.z;
     M->ez.y = M->ey.z;
     M->ez.z = det * (a11 * a22 - a12 * a12);
 }