Credits: Code adopted from Lode Vandevenne http://student.kuleuven.be/~m0216922/CG/ */ #ifndef _OFX_MATRIX_3X3 define _OFX_MATRIX_3X3

  class ofxMatrix3x3 {
  
    public:
  
      

[ a b c ] [ d e f ] [ g h i ]

  
      double a;
      double b;
      double c;
      double d;
      double e;
      double f;
      double g;
      double h;
      double i;
  
      ofxMatrix3x3( double _a=0.0, double _b=0.0, double _c=0.0,
                    double _d=0.0, double _e=0.0, double _f=0.0,
                    double _g=0.0, double _h=0.0, double _i=0.0 );
  
      void set( double _a, double _b, double _c,
                double _d, double _e, double _f,
                double _g, double _h, double _i );
  
      double& operator[]( const int& index );
  
          

Transpose: This changes the matrix. [ a b c ]T [ a d g ] [ d e f ] = [ b e h ] [ g h i ] [ c f i ]

  
  
          void transpose();
  
          

Transpose without changing the matrix. Uses the "swap" method with additions and subtractions to swap the elements that aren't on the main diagonal.
returns: transposed matrix.

  
  
          ofxMatrix3x3 transpose(const ofxMatrix3x3& A);
  
          

Determinant: http://mathworld.wolfram.com/Determinant.html

  
  
      double determinant() const;
  
      double determinant(const ofxMatrix3x3& A);
  
      

Inverse of a 3x3 matrix the inverse is the adjoint divided through the determinant find the matrix of minors (minor = determinant of 2x2 matrix of the 2 rows/colums current element is NOT in) turn them in cofactors (= change some of the signs) find the adjoint by transposing the matrix of cofactors divide this through the determinant to get the inverse

  
  
      void invert();
  
      ofxMatrix3x3 inverse(const ofxMatrix3x3& A);
  
      

Add two matrices

  
      ofxMatrix3x3 operator+(const ofxMatrix3x3& B);
  
      void operator+=(const ofxMatrix3x3& B);
  
      

Subtract two matrices

  
      ofxMatrix3x3 operator-(const ofxMatrix3x3& B);
  
          void operator-=(const ofxMatrix3x3& B);
  
      

Multiply a matrix with a scalar

  
      ofxMatrix3x3 operator*(double scalar);
  
          void operator*=(const ofxMatrix3x3& B);
  
      void operator*=(double scalar);
  
       

Multiply a 3x3 matrix with a 3x3 matrix

  
      ofxMatrix3x3 operator*(const ofxMatrix3x3& B);
  
      

Divide a matrix through a scalar

  
      ofxMatrix3x3 operator/(double scalar);
  
          void operator/=(const ofxMatrix3x3& B);
  
      void operator/=(double scalar);
  
  };
  
  endif
  
  

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[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

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(C) Æliens 04/09/2009

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