function [ o, x, w ] = en_her_03_1 ( n ) %*****************************************************************************80 % %% EN_HER_03_1 implements the Stroud rule 3.1 for region EN_HER. % % Discussion: % % The rule has order O = 2 * N. % % The rule has precision P = 3. % % EN_HER is the entire N-dimensional space with weight function % % w(x) = exp ( - x1^2 - x2^2 ... - xn^2 ) % % Licensing: % % This code is distributed under the GNU LGPL license. % % Modified: % % 20 January 2010 % % Author: % % John Burkardt % % Reference: % % Arthur Stroud, % Approximate Calculation of Multiple Integrals, % Prentice Hall, 1971, % ISBN: 0130438936, % LC: QA311.S85. % % Parameters: % % Input, integer N, the spatial dimension. % % Output, integer O, the order. % % Output, real X(N,O), the abscissas. % % Output, real W(O), the weights. % o = 2 * n; volume = sqrt ( pi^n ); a = volume / o; r = sqrt ( n / 2 ); x = zeros ( n, o ); w = zeros ( o, 1 ); k = 0; % % 2 * N points. % for i = 1 : n k = k + 1; x(i,k) = - r; w(k) = a; k = k + 1; x(i,k) = + r; w(k) = a; end return end