03 February 2008 11:43:48 AM INT_EXACTNESS_GEN_LAGUERRE C++ version Investigate the polynomial exactness of a generalized Gauss-Laguerre quadrature rule by integrating exponentially weighted monomials up to a given degree over the [0,+oo) interval. The rule may be defined on another interval [A,+oo) in which case it is adjusted to the [0,+oo) interval. INT_EXACTNESS_GEN_LAGUERRE: User input: Quadrature rule X file = "gen_lag_o1_a0.5_modified_x.txt". Quadrature rule W file = "gen_lag_o1_a0.5_modified_w.txt". Quadrature rule R file = "gen_lag_o1_a0.5_modified_r.txt". Maximum degree to check = 5 Weighting exponent ALPHA = 0.5 OPTION = 1, integrate f(x) Spatial dimension = 1 Number of points = 1 The quadrature rule to be tested is a generalized Gauss-Laguerre rule ORDER = 1 with A = 0 and ALPHA = 0.5 Modified rule: Integral ( A <= x < +oo ) f(x) dx is to be approximated by sum ( 1 <= I <= ORDER ) w(i) * f(x(i)). Weights W: w[ 0] = 3.2429558338367 Abscissas X: x[ 0] = 1.5 Region R: r[ 0] = 0 r[ 1] = 1e+30 A generalized Gauss-Laguerre rule would be able to exactly integrate monomials up to and including degree = 1 Error Degree 2.50550506363359e-16 0 1.67033670908906e-16 1 0.4000000000000001 2 0.742857142857143 3 0.9142857142857144 4 0.9766233766233766 5 INT_EXACTNESS_GEN_LAGUERRE: Normal end of execution. 03 February 2008 11:43:48 AM