From: David Wells Date: Mon, 14 Jun 2021 17:15:03 +0000 (-0400) Subject: Un-hardcode a simplex quadrature rule. X-Git-Tag: v9.4.0-rc1~1217^2 X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F12461%2Fhead;p=dealii.git Un-hardcode a simplex quadrature rule. This is easier to check (and somewhat more accurate) if we just use the definition. --- diff --git a/source/base/quadrature_lib.cc b/source/base/quadrature_lib.cc index 88ad96517d..cb755baeb8 100644 --- a/source/base/quadrature_lib.cc +++ b/source/base/quadrature_lib.cc @@ -1388,25 +1388,30 @@ QGaussSimplex::QGaussSimplex(const unsigned int n_points_1D) } else if (n_points_1D == 3) { - const double q12 = 0.5; + // The Hammer-Marlowe-Stroud 5 Scheme, as communicated by quadpy + const double p0 = 2.0 / 7.0 - std::sqrt(15.0) / 21.0; + const double p1 = 2.0 / 7.0 + std::sqrt(15.0) / 21.0; + const double p2 = 3.0 / 7.0 - 2.0 * std::sqrt(15.0) / 21.0; + const double p3 = 3.0 / 7.0 + 2.0 * std::sqrt(15.0) / 21.0; + this->quadrature_points.emplace_back(1.0 / 3.0, 1.0 / 3.0); + this->quadrature_points.emplace_back(p3, p0); + this->quadrature_points.emplace_back(p0, p3); + this->quadrature_points.emplace_back(p0, p0); + this->quadrature_points.emplace_back(p2, p1); + this->quadrature_points.emplace_back(p1, p2); + this->quadrature_points.emplace_back(p1, p1); - // clang-format off - this->quadrature_points.emplace_back(0.3333333333330, 0.3333333333330); - this->quadrature_points.emplace_back(0.7974269853530, 0.1012865073230); - this->quadrature_points.emplace_back(0.1012865073230, 0.7974269853530); - this->quadrature_points.emplace_back(0.1012865073230, 0.1012865073230); - this->quadrature_points.emplace_back(0.0597158717898, 0.4701420641050); - this->quadrature_points.emplace_back(0.4701420641050, 0.0597158717898); - this->quadrature_points.emplace_back(0.4701420641050, 0.4701420641050); - // clang-format on - - this->weights.emplace_back(q12 * 0.225); - this->weights.emplace_back(q12 * 0.125939180545); - this->weights.emplace_back(q12 * 0.125939180545); - this->weights.emplace_back(q12 * 0.125939180545); - this->weights.emplace_back(q12 * 0.132394152789); - this->weights.emplace_back(q12 * 0.132394152789); - this->weights.emplace_back(q12 * 0.132394152789); + const double q12 = 0.5; + const double w0 = 9.0 / 40.0; + const double w1 = 31.0 / 240.0 - std::sqrt(15.0) / 1200.0; + const double w2 = 31.0 / 240.0 + std::sqrt(15.0) / 1200.0; + this->weights.emplace_back(q12 * w0); + this->weights.emplace_back(q12 * w1); + this->weights.emplace_back(q12 * w1); + this->weights.emplace_back(q12 * w1); + this->weights.emplace_back(q12 * w2); + this->weights.emplace_back(q12 * w2); + this->weights.emplace_back(q12 * w2); } else if (n_points_1D == 4) {