class ROOT::Math::MatRepSym<double,4>

      MatRepStd
      Standard Matrix representation for a general D1 x D2 matrix.
      This class is itself a template on the contained type T, the number of rows and the number of columns.
      Its data member is an array T[nrows*ncols] containing the matrix data.
      The data are stored in the row-major C convention.
      For example, for a matrix, M, of size 3x3, the data \f$ \left[a_0,a_1,a_2,.......,a_7,a_8 \right] \f$d are stored in the following order:
      \f[
      M = \left( \begin{array}{ccc}
      a_0 & a_1 & a_2  \\
      a_3 & a_4  & a_5  \\
      a_6 & a_7  & a_8   \end{array} \right)
      \f]

      @ingroup MatRep