quadrature_monomial_2D.C

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// The libMesh Finite Element Library.
// Copyright (C) 2002-2025 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner

// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.

// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA



// Local includes
#include "libmesh/quadrature_monomial.h"
#include "libmesh/quadrature_gauss.h"

namespace libMesh
{


void QMonomial::init_2D()
{

  switch (_type)
    {
      //---------------------------------------------
      // Quadrilateral quadrature rules
    case QUAD4:
    case QUADSHELL4:
    case QUAD8:
    case QUADSHELL8:
    case QUAD9:
    case QUADSHELL9:
      {
        switch(get_order())
          {
          case SECOND:
            {
              // A degree=2 rule for the QUAD with 3 points.
              // A tensor product degree-2 Gauss would have 4 points.
              // This rule (or a variation on it) is probably available in
              //
              // A.H. Stroud, Approximate calculation of multiple integrals,
              // Prentice-Hall, Englewood Cliffs, N.J., 1971.
              //
              // though I have never actually seen a reference for it.
              // Luckily it's fairly easy to derive, which is what I've done
              // here [JWP].
              const Real
                s=std::sqrt(Real(1)/3), // ~0.57735026919
                t=std::sqrt(Real(2)/3); // ~0.81649658092

              const Real data[2][3] =
                {
                  {0.0,  s,  2.0},
                  {  t, -s,  1.0}
                };

              _points.resize(3);
              _weights.resize(3);

              wissmann_rule(data, 2);

              return;
            } // end case SECOND



            // For third-order, fall through to default case, use 2x2 Gauss product rule.
            // case THIRD:
            //   {
            //   }  // end case THIRD

            // Tabulated-in-double-precision rules aren't accurate enough for
            // higher precision, so fall back on Gauss
#if !defined(LIBMESH_DEFAULT_TRIPLE_PRECISION) && !defined(LIBMESH_DEFAULT_QUADRUPLE_PRECISION)
          case FOURTH:
            {
              // A pair of degree=4 rules for the QUAD "C2" due to
              // Wissmann and Becker. These rules both have six points.
              // A tensor product degree-4 Gauss would have 9 points.
              //
              // J. W. Wissmann and T. Becker, Partially symmetric cubature
              // formulas for even degrees of exactness, SIAM J. Numer. Anal.  23
              // (1986), 676--685.
              const Real data[4][3] =
                {
                  // First of 2 degree-4 rules given by Wissmann
                  {Real(0.0000000000000000e+00),  Real(0.0000000000000000e+00),  Real(1.1428571428571428e+00)},
                  {Real(0.0000000000000000e+00),  Real(9.6609178307929590e-01),  Real(4.3956043956043956e-01)},
                  {Real(8.5191465330460049e-01),  Real(4.5560372783619284e-01),  Real(5.6607220700753210e-01)},
                  {Real(6.3091278897675402e-01), Real(-7.3162995157313452e-01),  Real(6.4271900178367668e-01)}
                  //
                  // Second of 2 degree-4 rules given by Wissmann.  These both
                  // yield 4th-order accurate rules, I just chose the one that
                  // happened to contain the origin.
                  // {0.000000000000000, -0.356822089773090,  1.286412084888852},
                  // {0.000000000000000,  0.934172358962716,  0.491365692888926},
                  // {0.774596669241483,  0.390885162530071,  0.761883709085613},
                  // {0.774596669241483, -0.852765377881771,  0.349227402025498}
                };

              _points.resize(6);
              _weights.resize(6);

              wissmann_rule(data, 4);

              return;
            } // end case FOURTH
#endif




          case FIFTH:
            {
              // A degree 5, 7-point rule due to Stroud.
              //
              // A.H. Stroud, Approximate calculation of multiple integrals,
              // Prentice-Hall, Englewood Cliffs, N.J., 1971.
              //
              // This rule is provably minimal in the number of points.
              // A tensor-product rule accurate for "bi-quintic" polynomials would have 9 points.
              //              0,              0, ~1.14285714286
              //              0, ~0.96609178307, ~0.31746031746
              // ~0.77459666924, ~0.57735026919, ~0.55555555555
              const Real data[3][3] =
                {
                  {                   0,                      0, Real(8)/7  }, // 1
                  {                   0, std::sqrt(Real(14)/15), Real(20)/63}, // 2
                  {std::sqrt(Real(3)/5),   std::sqrt(Real(1)/3), Real(20)/36}  // 4
                };

              const unsigned int symmetry[3] = {
                0, // Origin
                7, // Central Symmetry
                6  // Rectangular
              };

              _points.resize (7);
              _weights.resize(7);

              stroud_rule(data, symmetry, 3);

              return;
            } // end case FIFTH




            // Tabulated-in-double-precision rules aren't accurate enough for
            // higher precision, so fall back on Gauss
#if !defined(LIBMESH_DEFAULT_TRIPLE_PRECISION) && !defined(LIBMESH_DEFAULT_QUADRUPLE_PRECISION)
          case SIXTH:
            {
              // A pair of degree=6 rules for the QUAD "C2" due to
              // Wissmann and Becker. These rules both have 10 points.
              // A tensor product degree-6 Gauss would have 16 points.
              //
              // J. W. Wissmann and T. Becker, Partially symmetric cubature
              // formulas for even degrees of exactness, SIAM J. Numer. Anal.  23
              // (1986), 676--685.
              const Real data[6][3] =
                {
                  // First of 2 degree-6, 10 point rules given by Wissmann
                  // {0.000000000000000,  0.836405633697626,  0.455343245714174},
                  // {0.000000000000000, -0.357460165391307,  0.827395973202966},
                  // {0.888764014654765,  0.872101531193131,  0.144000884599645},
                  // {0.604857639464685,  0.305985162155427,  0.668259104262665},
                  // {0.955447506641064, -0.410270899466658,  0.225474004890679},
                  // {0.565459993438754, -0.872869311156879,  0.320896396788441}
                  //
                  // Second of 2 degree-6, 10 point rules given by Wissmann.
                  // Either of these will work, I just chose the one with points
                  // slightly further into the element interior.
                  {Real(0.0000000000000000e+00),  Real(8.6983337525005900e-01),  Real(3.9275059096434794e-01)},
                  {Real(0.0000000000000000e+00), Real(-4.7940635161211124e-01),  Real(7.5476288124261053e-01)},
                  {Real(8.6374282634615388e-01),  Real(8.0283751620765670e-01),  Real(2.0616605058827902e-01)},
                  {Real(5.1869052139258234e-01),  Real(2.6214366550805818e-01),  Real(6.8999213848986375e-01)},
                  {Real(9.3397254497284950e-01), Real(-3.6309658314806653e-01),  Real(2.6051748873231697e-01)},
                  {Real(6.0897753601635630e-01), Real(-8.9660863276245265e-01),  Real(2.6956758608606100e-01)}
                };

              _points.resize(10);
              _weights.resize(10);

              wissmann_rule(data, 6);

              return;
            } // end case SIXTH
#endif




          case SEVENTH:
            {
              // A degree 7, 12-point rule due to Tyler, can be found in Stroud's book
              //
              // A.H. Stroud, Approximate calculation of multiple integrals,
              // Prentice-Hall, Englewood Cliffs, N.J., 1971.
              //
              // This rule is fully-symmetric and provably minimal in the number of points.
              // A tensor-product rule accurate for "bi-septic" polynomials would have 16 points.
              const Real
                r  = std::sqrt(Real(6)/7),                                    // ~0.92582009977
                s  = std::sqrt( (Real(114) - 3*std::sqrt(Real(583))) / 287 ), // ~0.38055443320
                t  = std::sqrt( (Real(114) + 3*std::sqrt(Real(583))) / 287 ), // ~0.80597978291
                B1 = Real(196)/810,                                           // ~0.24197530864
                B2 = 4 * (178981 + 2769*std::sqrt(Real(583))) / 1888920,      // ~0.52059291666
                B3 = 4 * (178981 - 2769*std::sqrt(Real(583))) / 1888920;      // ~0.23743177469

              const Real data[3][3] =
                {
                  {r, 0.0, B1}, // 4
                  {s, 0.0, B2}, // 4
                  {t, 0.0, B3}  // 4
                };

              const unsigned int symmetry[3] = {
                3, // Full Symmetry, (x,0)
                2, // Full Symmetry, (x,x)
                2  // Full Symmetry, (x,x)
              };

              _points.resize (12);
              _weights.resize(12);

              stroud_rule(data, symmetry, 3);

              return;
            } // end case SEVENTH




            // Tabulated-in-double-precision rules aren't accurate enough for
            // higher precision, so fall back on Gauss
#if !defined(LIBMESH_DEFAULT_TRIPLE_PRECISION) && !defined(LIBMESH_DEFAULT_QUADRUPLE_PRECISION)
          case EIGHTH:
            {
              // A pair of degree=8 rules for the QUAD "C2" due to
              // Wissmann and Becker. These rules both have 16 points.
              // A tensor product degree-6 Gauss would have 25 points.
              //
              // J. W. Wissmann and T. Becker, Partially symmetric cubature
              // formulas for even degrees of exactness, SIAM J. Numer. Anal.  23
              // (1986), 676--685.
              const Real data[10][3] =
                {
                  // First of 2 degree-8, 16 point rules given by Wissmann
                  // {0.000000000000000,  0.000000000000000,  0.055364705621440},
                  // {0.000000000000000,  0.757629177660505,  0.404389368726076},
                  // {0.000000000000000, -0.236871842255702,  0.533546604952635},
                  // {0.000000000000000, -0.989717929044527,  0.117054188786739},
                  // {0.639091304900370,  0.950520955645667,  0.125614417613747},
                  // {0.937069076924990,  0.663882736885633,  0.136544584733588},
                  // {0.537083530541494,  0.304210681724104,  0.483408479211257},
                  // {0.887188506449625, -0.236496718536120,  0.252528506429544},
                  // {0.494698820670197, -0.698953476086564,  0.361262323882172},
                  // {0.897495818279768, -0.900390774211580,  0.085464254086247}
                  //
                  // Second of 2 degree-8, 16 point rules given by Wissmann.
                  // Either of these will work, I just chose the one with points
                  // further into the element interior.
                  {Real(0.0000000000000000e+00),  Real(6.5956013196034176e-01),  Real(4.5027677630559029e-01)},
                  {Real(0.0000000000000000e+00), Real(-9.4914292304312538e-01),  Real(1.6657042677781274e-01)},
                  {Real(9.5250946607156228e-01),  Real(7.6505181955768362e-01),  Real(9.8869459933431422e-02)},
                  {Real(5.3232745407420624e-01),  Real(9.3697598108841598e-01),  Real(1.5369674714081197e-01)},
                  {Real(6.8473629795173504e-01),  Real(3.3365671773574759e-01),  Real(3.9668697607290278e-01)},
                  {Real(2.3314324080140552e-01), Real(-7.9583272377396852e-02),  Real(3.5201436794569501e-01)},
                  {Real(9.2768331930611748e-01), Real(-2.7224008061253425e-01),  Real(1.8958905457779799e-01)},
                  {Real(4.5312068740374942e-01), Real(-6.1373535339802760e-01),  Real(3.7510100114758727e-01)},
                  {Real(8.3750364042281223e-01), Real(-8.8847765053597136e-01),  Real(1.2561879164007201e-01)}
                };

              _points.resize(16);
              _weights.resize(16);

              wissmann_rule(data, /*10*/ 9);

              return;
            } // end case EIGHTH




          case NINTH:
            {
              // A degree 9, 17-point rule due to Moller.
              //
              // H.M. Moller,  Kubaturformeln mit minimaler Knotenzahl,
              // Numer. Math.  25 (1976), 185--200.
              //
              // This rule is provably minimal in the number of points.
              // A tensor-product rule accurate for "bi-ninth" degree polynomials would have 25 points.
              const Real data[5][3] =
                {
                  {Real(0.0000000000000000e+00), Real(0.0000000000000000e+00), Real(5.2674897119341563e-01)}, // 1
                  {Real(6.3068011973166885e-01), Real(9.6884996636197772e-01), Real(8.8879378170198706e-02)}, // 4
                  {Real(9.2796164595956966e-01), Real(7.5027709997890053e-01), Real(1.1209960212959648e-01)}, // 4
                  {Real(4.5333982113564719e-01), Real(5.2373582021442933e-01), Real(3.9828243926207009e-01)}, // 4
                  {Real(8.5261572933366230e-01), Real(7.6208328192617173e-02), Real(2.6905133763978080e-01)}  // 4
                };

              const unsigned int symmetry[5] = {
                0, // Single point
                4, // Rotational Invariant
                4, // Rotational Invariant
                4, // Rotational Invariant
                4  // Rotational Invariant
              };

              _points.resize (17);
              _weights.resize(17);

              stroud_rule(data, symmetry, 5);

              return;
            } // end case NINTH




          case TENTH:
          case ELEVENTH:
            {
              // A degree 11, 24-point rule due to Cools and Haegemans.
              //
              // R. Cools and A. Haegemans, Another step forward in searching for
              // cubature formulae with a minimal number of knots for the square,
              // Computing 40 (1988), 139--146.
              //
              // P. Verlinden and R. Cools, The algebraic construction of a minimal
              // cubature formula of degree 11 for the square, Cubature Formulas
              // and their Applications (Russian) (Krasnoyarsk) (M.V. Noskov, ed.),
              // 1994, pp. 13--23.
              //
              // This rule is provably minimal in the number of points.
              // A tensor-product rule accurate for "bi-tenth" or "bi-eleventh" degree polynomials would have 36 points.
              const Real data[6][3] =
                {
                  {Real(6.9807610454956756e-01), Real(9.8263922354085547e-01), Real(4.8020763350723814e-02)}, // 4
                  {Real(9.3948638281673690e-01), Real(8.2577583590296393e-01), Real(6.6071329164550595e-02)}, // 4
                  {Real(9.5353952820153201e-01), Real(1.8858613871864195e-01), Real(9.7386777358668164e-02)}, // 4
                  {Real(3.1562343291525419e-01), Real(8.1252054830481310e-01), Real(2.1173634999894860e-01)}, // 4
                  {Real(7.1200191307533630e-01), Real(5.2532025036454776e-01), Real(2.2562606172886338e-01)}, // 4
                  {Real(4.2484724884866925e-01), Real(4.1658071912022368e-02), Real(3.5115871839824543e-01)}  // 4
                };

              const unsigned int symmetry[6] = {
                4, // Rotational Invariant
                4, // Rotational Invariant
                4, // Rotational Invariant
                4, // Rotational Invariant
                4, // Rotational Invariant
                4  // Rotational Invariant
              };

              _points.resize (24);
              _weights.resize(24);

              stroud_rule(data, symmetry, 6);

              return;
            } // end case TENTH,ELEVENTH




          case TWELFTH:
          case THIRTEENTH:
            {
              // A degree 13, 33-point rule due to Cools and Haegemans.
              //
              // R. Cools and A. Haegemans, Another step forward in searching for
              // cubature formulae with a minimal number of knots for the square,
              // Computing 40 (1988), 139--146.
              //
              // A tensor-product rule accurate for "bi-12" or "bi-13" degree polynomials would have 49 points.
              const Real data[9][3] =
                {
                  {Real(0.0000000000000000e+00), Real(0.0000000000000000e+00), Real(3.0038211543122536e-01)}, // 1
                  {Real(9.8348668243987226e-01), Real(7.7880971155441942e-01), Real(2.9991838864499131e-02)}, // 4
                  {Real(8.5955600564163892e-01), Real(9.5729769978630736e-01), Real(3.8174421317083669e-02)}, // 4
                  {Real(9.5892517028753485e-01), Real(1.3818345986246535e-01), Real(6.0424923817749980e-02)}, // 4
                  {Real(3.9073621612946100e-01), Real(9.4132722587292523e-01), Real(7.7492738533105339e-02)}, // 4
                  {Real(8.5007667369974857e-01), Real(4.7580862521827590e-01), Real(1.1884466730059560e-01)}, // 4
                  {Real(6.4782163718701073e-01), Real(7.5580535657208143e-01), Real(1.2976355037000271e-01)}, // 4
                  {Real(7.0741508996444936e-02), Real(6.9625007849174941e-01), Real(2.1334158145718938e-01)}, // 4
                  {Real(4.0930456169403884e-01), Real(3.4271655604040678e-01), Real(2.5687074948196783e-01)}  // 4
                };

              const unsigned int symmetry[9] = {
                0, // Single point
                4, // Rotational Invariant
                4, // Rotational Invariant
                4, // Rotational Invariant
                4, // Rotational Invariant
                4, // Rotational Invariant
                4, // Rotational Invariant
                4, // Rotational Invariant
                4  // Rotational Invariant
              };

              _points.resize (33);
              _weights.resize(33);

              stroud_rule(data, symmetry, 9);

              return;
            } // end case TWELFTH,THIRTEENTH




          case FOURTEENTH:
          case FIFTEENTH:
            {
              // A degree-15, 48 point rule originally due to Rabinowitz and Richter,
              // can be found in Cools' 1971 book.
              //
              // A.H. Stroud, Approximate calculation of multiple integrals,
              // Prentice-Hall, Englewood Cliffs, N.J., 1971.
              //
              // The product Gauss rule for this order has 8^2=64 points.
              const Real data[9][3] =
                {
                  {9.915377816777667e-01_R, 0.0000000000000000e+00 ,  3.01245207981210e-02_R}, // 4
                  {8.020163879230440e-01_R, 0.0000000000000000e+00 ,  8.71146840209092e-02_R}, // 4
                  {5.648674875232742e-01_R, 0.0000000000000000e+00 , 1.250080294351494e-01_R}, // 4
                  {9.354392392539896e-01_R, 0.0000000000000000e+00 ,  2.67651407861666e-02_R}, // 4
                  {7.624563338825799e-01_R, 0.0000000000000000e+00 ,  9.59651863624437e-02_R}, // 4
                  {2.156164241427213e-01_R, 0.0000000000000000e+00 , 1.750832998343375e-01_R}, // 4
                  {9.769662659711761e-01_R, 6.684480048977932e-01_R,  2.83136372033274e-02_R}, // 4
                  {8.937128379503403e-01_R, 3.735205277617582e-01_R,  8.66414716025093e-02_R}, // 4
                  {6.122485619312083e-01_R, 4.078983303613935e-01_R, 1.150144605755996e-01_R}  // 4
                };

              const unsigned int symmetry[9] = {
                3, // Full Symmetry, (x,0)
                3, // Full Symmetry, (x,0)
                3, // Full Symmetry, (x,0)
                2, // Full Symmetry, (x,x)
                2, // Full Symmetry, (x,x)
                2, // Full Symmetry, (x,x)
                1, // Full Symmetry, (x,y)
                1, // Full Symmetry, (x,y)
                1, // Full Symmetry, (x,y)
              };

              _points.resize (48);
              _weights.resize(48);

              stroud_rule(data, symmetry, 9);

              return;
            } //   case FOURTEENTH, FIFTEENTH:




          case SIXTEENTH:
          case SEVENTEENTH:
            {
              // A degree 17, 60-point rule due to Cools and Haegemans.
              //
              // R. Cools and A. Haegemans, Another step forward in searching for
              // cubature formulae with a minimal number of knots for the square,
              // Computing 40 (1988), 139--146.
              //
              // A tensor-product rule accurate for "bi-14" or "bi-15" degree polynomials would have 64 points.
              // A tensor-product rule accurate for "bi-16" or "bi-17" degree polynomials would have 81 points.
              const Real data[10][3] =
                {
                  {Real(9.8935307451260049e-01), Real(0.0000000000000000e+00), Real(2.0614915919990959e-02)}, // 4
                  {Real(3.7628520715797329e-01), Real(0.0000000000000000e+00), Real(1.2802571617990983e-01)}, // 4
                  {Real(9.7884827926223311e-01), Real(0.0000000000000000e+00), Real(5.5117395340318905e-03)}, // 4
                  {Real(8.8579472916411612e-01), Real(0.0000000000000000e+00), Real(3.9207712457141880e-02)}, // 4
                  {Real(1.7175612383834817e-01), Real(0.0000000000000000e+00), Real(7.6396945079863302e-02)}, // 4
                  {Real(5.9049927380600241e-01), Real(3.1950503663457394e-01), Real(1.4151372994997245e-01)}, // 8
                  {Real(7.9907913191686325e-01), Real(5.9797245192945738e-01), Real(8.3903279363797602e-02)}, // 8
                  {Real(8.0374396295874471e-01), Real(5.8344481776550529e-02), Real(6.0394163649684546e-02)}, // 8
                  {Real(9.3650627612749478e-01), Real(3.4738631616620267e-01), Real(5.7387752969212695e-02)}, // 8
                  {Real(9.8132117980545229e-01), Real(7.0600028779864611e-01), Real(2.1922559481863763e-02)}, // 8
                };

              const unsigned int symmetry[10] = {
                3, // Fully symmetric (x,0)
                3, // Fully symmetric (x,0)
                2, // Fully symmetric (x,x)
                2, // Fully symmetric (x,x)
                2, // Fully symmetric (x,x)
                1, // Fully symmetric (x,y)
                1, // Fully symmetric (x,y)
                1, // Fully symmetric (x,y)
                1, // Fully symmetric (x,y)
                1  // Fully symmetric (x,y)
              };

              _points.resize (60);
              _weights.resize(60);

              stroud_rule(data, symmetry, 10);

              return;
            } // end case FOURTEENTH through SEVENTEENTH
#endif



            // By default: construct and use a Gauss quadrature rule
          default:
            {
              // Break out and fall down into the default: case for the
              // outer switch statement.
              break;
            }

          } // end switch(_order + 2*p)
      } // end case QUAD4/8/9

      libmesh_fallthrough();

      // By default: construct and use a Gauss quadrature rule
    default:
      {
        QGauss gauss_rule(2, _order);
        gauss_rule.init(*this);

        // Swap points and weights with the about-to-be destroyed rule.
        _points.swap (gauss_rule.get_points() );
        _weights.swap(gauss_rule.get_weights());

        return;
      }
    } // end switch (_type)
}

} // namespace libMesh