# File lib/backports/1.9.2/stdlib/matrix/eigenvalue_decomposition.rb, line 18
    def initialize(a)
      # @d, @e: Arrays for internal storage of eigenvalues.
      # @v: Array for internal storage of eigenvectors.
      # @h: Array for internal storage of nonsymmetric Hessenberg form.
      raise TypeError, "Expected Matrix but got #{a.class}" unless a.is_a?(Matrix)
      @size = a.row_size
      @d = Array.new(@size, 0)
      @e = Array.new(@size, 0)

      if (@symmetric = a.symmetric?)
        @v = a.to_a
        tridiagonalize
        diagonalize
      else
        @v = Array.new(@size) { Array.new(@size, 0) }
        @h = a.to_a
        @ort = Array.new(@size, 0)
        reduce_to_hessenberg
        hessenberg_to_real_schur
      end
    end