function [ x, w ] = gauss_ab ( n, a, b )

%% gauss_ab returns a Gauss quadrature rule for [a,b].
%
  [ xi, rho] = gauss ( n );

  x = a + ( xi + 1.0 ) * ( b - a ) / 2.0;
  w = ( b - a ) * rho / 2.0;

  return
end
