function u = solve ( adiag, aleft, arite, f, nu )

%% SOLVE solves a tridiagonal matrix system of the form A*x = b.
%
%  Modified:
%
%    06 November 2006
%
%  Parameters:
%
%    Input, real ADIAG(NU), ALEFT(NU), ARITE(NU).
%    the diagonal, left and right entries of the equations.
%
%    Input, real F(NU), the right hand side of the linear system.
%
%    Input, INTEGER NU, the number of equations to be solved.
%
%    Output, real U(NU), the solution of the linear system.
%

%
%  Handle the special case of a single equation.
%
  if ( nu == 1 )

    u(1) = f(1) / adiag(1);
%
%  The general case, when NU is greater than 1.
%
  else

    arite(1) = arite(1) / adiag(1);
    for i = 2 : nu-1
      adiag(i) = adiag(i) - aleft(i) * arite(i-1);
      arite(i) = arite(i) / adiag(i);
    end
    adiag(nu) = adiag(nu) - aleft(nu) * arite(nu-1);

    u(1) = f(1) / adiag(1);
    for i = 2 : nu
      u(i) = ( f(i) - aleft(i) * u(i-1) ) / adiag(i);
    end

    for i = nu-1 : -1 : 1
      u(i) = u(i) - arite(i) * u(i+1);
    end

  end