class ROOT::Math::SMatrix<double,6,6,ROOT::Math::MatRepSym<double,6> >

       Assign from another compatible matrix.
       Possible Symmetirc to general but NOT vice-versa

       Assign from a matrix expression

      Assign from an identity matrix

 @name --- Access functions --- 
 access the parse tree with the index starting from zero and
       following the C convention for the order in accessing
       the matrix elements.
       Same convention for general and symmetric matrices.

 return read-only pointer to internal array

 @name --- STL-like interface ---
       The iterators access the matrix element in the order how they are
       stored in memory. The C (row-major) convention is used, and in the
       case of symmetric matrices the iterator spans only the lower diagonal
       block. For example for a symmetric 3x3 matrices the order of the 6
       elements \f${a_0,...a_5}\f$ is:
       \f[
       M = \left( \begin{array}{ccc}
       a_0 & a_1 & a_3  \\
       a_1 & a_2  & a_4  \\
       a_3 & a_4 & a_5   \end{array} \right)
       \f]

 STL iterator interface. 

 STL iterator interface. 

 STL const_iterator interface. 

 STL const_iterator interface. 

 @name --- Operators --- 
 element wise comparison

 element wise comparison

 element wise comparison

 element wise comparison

 element wise comparison

      read only access to matrix element, with indices starting from 0

      read only access to matrix element, with indices starting from 0.
      Fuction will check index values and it will assert if they are wrong

      addition with a scalar

      subtraction with a scalar

      multiplication with a scalar

      division with a scalar

 @name --- Linear Algebra Functions --- 

      Invert a square Matrix ( this method changes the current matrix).
      Return true if inversion is successfull.
      The method used for general square matrices is the LU factorization taken from Dinv routine
      from the CERNLIB (written in C++ from CLHEP authors)
      In case of symmetric matrices Bunch-Kaufman diagonal pivoting method is used
      (The implementation is the one written by the CLHEP authors)

      Invert a square Matrix and  returns a new matrix. In case the inversion fails
      the current matrix is returned.
      \param ifail . ifail will be set to 0 when inversion is successfull.
      See ROOT::Math::SMatrix::Invert for the inversion algorithm

      Fast Invertion of a square Matrix ( this method changes the current matrix).
      Return true if inversion is successfull.
      The method used is based on direct inversion using the Cramer rule for
      matrices upto 5x5. Afterwards the same defult algorithm of Invert() is used.
      Note that this method is faster but can suffer from much larger numerical accuracy
      when the condition of the matrix is large

      Invert a square Matrix and  returns a new matrix. In case the inversion fails
      the current matrix is returned.
      \param ifail . ifail will be set to 0 when inversion is successfull.
      See ROOT::Math::SMatrix::InvertFast for the inversion algorithm

      Invertion of a symmetric positive defined Matrix using Choleski decomposition.
      ( this method changes the current matrix).
      Return true if inversion is successfull.
      The method used is based on Choleski decomposition
      A compile error is given if the matrix is not of type symmetric and a run-time failure if the
      matrix is not positive defined.
      For solving  a linear system, it is possible to use also the function
      ROOT::Math::SolveChol(matrix, vector) which will be faster than performing the inversion

      Invert of a symmetric positive defined Matrix using Choleski decomposition.
      A compile error is given if the matrix is not of type symmetric and a run-time failure if the
      matrix is not positive defined.
      In case the inversion fails the current matrix is returned.
      \param ifail . ifail will be set to 0 when inversion is successfull.
      See ROOT::Math::SMatrix::InvertChol for the inversion algorithm

      determinant of square Matrix via Dfact.
      Return true when the calculation is successfull.
      \param det will contain the calculated determinant value
      \b Note: this will destroy the contents of the Matrix!

      determinant of square Matrix via Dfact.
      Return true when the calculation is successfull.
      \param det will contain the calculated determinant value
      \b Note: this will preserve the content of the Matrix!

      return a full Matrix row as a vector (copy the content in a new vector)

      return a full Matrix column as a vector (copy the content in a new vector)

      return diagonal elements of a matrix as a Vector.
      It works only for squared matrices D1 == D2, otherwise it will produce a compile error

      return the trace of a matrix
      Sum of the diagonal elements

 @name --- Other Functions --- 

       Function to check if a matrix is sharing same memory location of the passed pointer
       This function is used by the expression templates to avoid the alias problem during
       expression evaluation. When  the matrix is in use, for example in operations
       like A = B * A, a temporary object storing the intermediate result is automatically
       created when evaluating the expression.

 submatrices
 Print: used by operator<<()