Wolfram Demonstrations Projecthttp://demonstrations.wolfram.com/An Open Resource of Interactive Mathematica VisualizationsCopyright 2009 Wolfram Demonstrations Project & Contributors3D Graph of a General Quadratic Formhttp://demonstrations.wolfram.com/3DGraphOfAGeneralQuadraticForm/]]>http://demonstrations.wolfram.com/3DGraphOfAGeneralQuadraticForm/