From 642a3e509432816a4313aedb4792ac8ef79e5cdc Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Mon, 22 Oct 2012 16:21:27 +0200
Subject: [PATCH] 0000856: Wrong inverse of a matrix

---
 src/Base/Matrix.h         | 4 +++-
 src/Base/MatrixPyImp.cpp  | 4 ++--
 src/Mod/Test/BaseTests.py | 5 +++++
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/Base/Matrix.h b/src/Base/Matrix.h
index b6aa5349d..63ac6db79 100644
--- a/src/Base/Matrix.h
+++ b/src/Base/Matrix.h
@@ -134,9 +134,11 @@ public:
   /// transform (move,scale,rotate) around a point
   void transform    (const Vector3f& rclVct, const Matrix4D& rclMtrx);
   void transform    (const Vector3d& rclVct, const Matrix4D& rclMtrx);
+  /// Matrix is expected to have a 3x3 rotation matrix.
   void inverse      (void);
-  /// if matrix is orthogonal a special way of getting the inverse is used
+  /// Matrix is expected to have a 3x3 rotation matrix.
   void inverseOrthogonal(void);
+  /// Arbitrary, non-singular matrix
   void inverseGauss (void);
   void transpose    (void);
   //@}
diff --git a/src/Base/MatrixPyImp.cpp b/src/Base/MatrixPyImp.cpp
index b7d594f54..5c7eda29c 100644
--- a/src/Base/MatrixPyImp.cpp
+++ b/src/Base/MatrixPyImp.cpp
@@ -342,7 +342,7 @@ PyObject* MatrixPy::invert(PyObject * args)
 
     PY_TRY {
         if (getMatrixPtr()->determinant() > DBL_EPSILON)
-            getMatrixPtr()->inverse();
+            getMatrixPtr()->inverseGauss();
         else {
             PyErr_SetString(PyExc_Exception, "Cannot invert singular matrix");
             return 0;
@@ -361,7 +361,7 @@ PyObject* MatrixPy::inverse(PyObject * args)
     PY_TRY {
         if (getMatrixPtr()->determinant() > DBL_EPSILON) {
             Base::Matrix4D m = *getMatrixPtr();
-            m.inverse();
+            m.inverseGauss();
             return new MatrixPy(m);
         }
         else {
diff --git a/src/Mod/Test/BaseTests.py b/src/Mod/Test/BaseTests.py
index c6442ce05..97ceb4f6a 100644
--- a/src/Mod/Test/BaseTests.py
+++ b/src/Mod/Test/BaseTests.py
@@ -149,6 +149,11 @@ class ParameterTestCase(unittest.TestCase):
         self.TestPar.RemString("44")
         self.failUnless(self.TestPar.GetString("44","hallo") == "hallo","Deletion error at String")
 
+    def testMatrix(self):
+        m=FreeCAD.Matrix(4,2,1,0,1,1,1,0,0,0,1,0,0,0,0,1)
+        u=m.multiply(m.inverse())
+        self.failUnless(u==FreeCAD.Matrix(),"Invalid inverse of matrix")
+
     def testNesting(self):
         # Parameter testing
         #FreeCAD.Console.PrintLog("Base::ParameterTestCase::testNesting\n")