22 January 2009 9:23:04.630 AM INT_EXACTNESS_LEGENDRE FORTRAN90 version Investigate the polynomial exactness of a Gauss-Legendre quadrature rule by integrating weighted monomials up to a given degree over the [-1,+1] interval. INT_EXACTNESS_LEGENDRE: User input: Quadrature rule X file = "leg_o8_x.txt". Quadrature rule W file = "leg_o8_w.txt". Quadrature rule R file = "leg_o8_r.txt". Maximum degree to check = 18 Spatial dimension = 1 Number of points = 8 The quadrature rule to be tested is a Gauss-Legendre rule ORDER = 8 Standard rule: Integral ( -1 <= x <= +1 ) f(x) dx is to be approximated by sum ( 1 <= I <= ORDER ) w(i) * f(x(i)). Weights W: w( 1) = 0.1012285362903761 w( 2) = 0.2223810344533745 w( 3) = 0.3137066458778873 w( 4) = 0.3626837833783620 w( 5) = 0.3626837833783620 w( 6) = 0.3137066458778873 w( 7) = 0.2223810344533745 w( 8) = 0.1012285362903761 Abscissas X: x( 1) = -0.9602898564975364 x( 2) = -0.7966664774136267 x( 3) = -0.5255324099163290 x( 4) = -0.1834346424956498 x( 5) = 0.1834346424956498 x( 6) = 0.5255324099163290 x( 7) = 0.7966664774136267 x( 8) = 0.9602898564975364 Region R: r( 1) = -1.0000000000000000 r( 2) = 1.0000000000000000 A Gauss-Legendre rule would be able to exactly integrate monomials up to and including degree = 15 Error Error Degree (This rule) (Trapezoid) 0.0000000000000000 0.0000000000000002 0 0.0000000000000000 0.0000000000000001 1 0.0000000000000000 0.0408163265306121 2 0.0000000000000000 0.0000000000000000 3 0.0000000000000003 0.1349437734277384 4 0.0000000000000000 0.0000000000000000 5 0.0000000000000002 0.2780304124981938 6 0.0000000000000000 0.0000000000000000 7 0.0000000000000001 0.4628822399940606 8 0.0000000000000000 0.0000000000000000 9 0.0000000000000003 0.6807392105352211 10 0.0000000000000000 0.0000000000000000 11 0.0000000000000005 0.9228001872701588 12 0.0000000000000000 0.0000000000000000 13 0.0000000000000010 1.1814556860179242 14 0.0000000000000000 0.0000000000000000 15 0.0003956606287597 1.4508791292288041 16 0.0000000000000000 0.0000000000000000 17 0.0018727936427998 1.7270038958037262 18 INT_EXACTNESS_LEGENDRE: Normal end of execution. 22 January 2009 9:23:04.633 AM