Program Listing for File check_tableau.m

↰ Return to documentation for file (+Indigo/@RungeKutta/check_tableau.m)

%> Check Butcher tableau consistency for an explicit Runge-Kutta method.
%>
%> \param tbl.A   Matrix \f$ \mathbf{A} \f$.
%> \param tbl.b   Weights vector \f$ \mathbf{b} \f$.
%> \param tbl.b_e [optional] Embedded weights vector \f$ \hat{\mathbf{b}}
%>                \f$ (row vector).
%> \param tbl.c   Nodes vector \f$ \mathbf{c} \f$.
%>
%> \return True if the Butcher tableau is consistent, false otherwise.
%
function [out, order, e_order] = check_tableau( this, tbl )

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

  % Collect input data
  A   = tbl.A;
  b   = tbl.b;
  b_e = tbl.b_e;
  c   = tbl.c;

  % Prepare output
  out = true;

  % Check matrix A
  if ~all(isnumeric(A))
    warning([CMD, 'A must be a numeric matrix.']);
    out = false;
  end
  if (size(A, 1) ~= size(A, 2))
    warning([CMD, 'matrix A is not a square matrix.']);
    out = false;
  end
  if ~all(isfinite(A))
    warning([CMD, 'matrix A found with NaN or Inf values.']);
    out = false;
  end

  % Check vector b
  if ~all(isnumeric(b))
    warning([CMD, 'b must be a numeric vector.']);
    out = false;
  end
  if ~all(isfinite(b))
    warning([CMD, 'matrix b found with NaN or Inf values.']);
    out = false;
  end
  if ~isrow(b)
    warning([CMD, 'vector b is not a row vector.']);
    out = false;
  end
  if (size(A, 2) ~= size(b, 2))
    warning([CMD, 'vector b is not consistent with the size of matrix A.']);
    out = false;
  end

  % Check vector b_e
  if ~isempty(b_e)
    if ~isnumeric(b_e)
      warning([CMD, 'b_e must be a numeric vector.']);
      out = false;
    end
   if ~all(isfinite(b_e))
      warning([CMD, 'vector b_e found with NaN or Inf values.']);
      out = false;
    end
    if ~isrow(b_e)
      warning([CMD, 'vector b_e is not a row vector.']);
      out = false;
    end
    if (size(A, 2) ~= size(b_e, 2))
      warning([CMD, 'vector b_e is not consistent with the size of matrix A.']);
      out = false;
    end
  end

  % Check vector c
  if ~all(isnumeric(c))
    warning([CMD, 'c must be a numeric vector.']);
    out = false;
  end
  if ~all(isfinite(c))
    warning([CMD, 'vector c found with NaN or Inf values.']);
    out = false;
  end
  if ~iscolumn(c)
    warning([CMD, 'vector c is not a column vector.']);
    out = false;
  end
  if (size(A, 1) ~= size(c, 1))
    warning([CMD, 'vector c is not consistent with the size of matrix A.']);
    out = false;
  end

  % Check consistency
  [order, msg] = this.tableau_order(A, b, c);

  if (order ~= this.m_order)
    %warning(sprintf([CMD, 'order %d, expected %d.\n', msg], order, this.m_order));
    out = false;
  end

  if ~isempty(b_e)
    [e_order, msg] = this.tableau_order(A, b_e, c);
    %fprintf([CMD, '\norder = %d, embedded order = %d.\n'], order, e_order);
  else
    e_order = 0;
    %fprintf([CMD, '\norder = %d.\n'], order);
  end

end