CPPLapack Code

//=============================================================================
/*! calculate determinant */
inline double det(const dgemat3& A)
{
  return
    +A(0,0)*A(1,1)*A(2,2) -A(0,0)*A(1,2)*A(2,1)
    +A(0,1)*A(1,2)*A(2,0) -A(0,1)*A(1,0)*A(2,2)
    +A(0,2)*A(1,0)*A(2,1) -A(0,2)*A(1,1)*A(2,0);
}

//=============================================================================
/*! calculate inverse */
inline dgemat3 inv(const dgemat3& A)
{
  const double Adet( det(A) );
  dgemat3 Ainv;
  Ainv(0,0) =(A(1,1)*A(2,2)-A(1,2)*A(2,1))/Adet;
  Ainv(0,1) =(A(0,2)*A(2,1)-A(0,1)*A(2,2))/Adet;
  Ainv(0,2) =(A(0,1)*A(1,2)-A(0,2)*A(1,1))/Adet;
  Ainv(1,0) =(A(1,2)*A(2,0)-A(1,0)*A(2,2))/Adet;
  Ainv(1,1) =(A(0,0)*A(2,2)-A(0,2)*A(2,0))/Adet;
  Ainv(1,2) =(A(0,2)*A(1,0)-A(0,0)*A(1,2))/Adet;
  Ainv(2,0) =(A(1,0)*A(2,1)-A(1,1)*A(2,0))/Adet;
  Ainv(2,1) =(A(0,1)*A(2,0)-A(0,0)*A(2,1))/Adet;
  Ainv(2,2) =(A(0,0)*A(1,1)-A(0,1)*A(1,0))/Adet;
  return Ainv;
}

//=============================================================================
/*!  */
inline dgemat3 rotate(const dgemat3& m, const dquater& q)
{
  dgemat3 R(q2m(q));
  return R*m*t(R);
}

//=============================================================================
/*!  */
inline dquater m2q(const dgemat3& m)
{
  dcovec3 v( m(2,1)-m(1,2), m(0,2)-m(2,0), m(1,0)-m(0,1) );
  double t( acos(0.5*(m(0,0)+m(1,1)+m(2,2)-1.)) );
  return vt2q(v,t);
}