Program Listing for File set_tableau.m

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%> Set the Butcher tableau.
%>
%> \param tbl.A   Matrix \f$ \mathbf{A} \f$ (lower triangular matrix).
%> \param tbl.b   Weights vector \f$ \mathbf{b} \f$ (row vector).
%> \param tbl.b_e [optional] Embedded weights vector \f$ \hat{\mathbf{b}} \f$
%>                (row vector).
%> \param tbl.c   Nodes vector \f$ \mathbf{c} \f$ (column vector).
%
function set_tableau( this, tbl )

  CMD = 'Indigo.RungeKutta.set_tableau(...): ';

  % Check the Butcher tableau
  [ok, ~, ~] = this.check_tableau(tbl);
  assert(ok, [CMD, 'invalid tableau detected.']);

  % Set the tableau
  this.m_A   = tbl.A;
  this.m_b   = tbl.b;
  this.m_b_e = tbl.b_e;
  this.m_c   = tbl.c;

  % Set boolean flags
  if istril(this.m_A)
    if all(diag(this.m_A)==0)
      % Explicit tableau
      this.m_rk_type = 'ERK';
    elseif (length(this.m_c) > 1)
      % Diagonally implicit tableau
      this.m_rk_type = 'DIRK';
    else
      % Mixed case, threat it as implicit
      this.m_rk_type = 'IRK';
    end
  else
    this.m_rk_type = 'IRK';
  end
  this.m_is_embedded = ~isempty(this.m_b_e);

  % Update the solver properties
  this.m_adaptive_step = this.m_is_embedded;
end