xref: /libCEED/examples/petsc/qfunctions/area/areacube.h (revision 05a9c2bb2f62eff0bfbb15aec60b0312b25f01c2)
1 // Copyright (c) 2017, Lawrence Livermore National Security, LLC. Produced at
2 // the Lawrence Livermore National Laboratory. LLNL-CODE-734707. All Rights
3 // reserved. See files LICENSE and NOTICE for details.
4 //
5 // This file is part of CEED, a collection of benchmarks, miniapps, software
6 // libraries and APIs for efficient high-order finite element and spectral
7 // element discretizations for exascale applications. For more information and
8 // source code availability see http://github.com/ceed.
9 //
10 // The CEED research is supported by the Exascale Computing Project 17-SC-20-SC,
11 // a collaborative effort of two U.S. Department of Energy organizations (Office
12 // of Science and the National Nuclear Security Administration) responsible for
13 // the planning and preparation of a capable exascale ecosystem, including
14 // software, applications, hardware, advanced system engineering and early
15 // testbed platforms, in support of the nation's exascale computing imperative.
16 
17 /// @file
18 /// libCEED QFunctions for mass operator example for a scalar field on the sphere using PETSc
19 
20 #ifndef areacube_h
21 #define areacube_h
22 
23 #ifndef __CUDACC__
24 #  include <math.h>
25 #endif
26 
27 // -----------------------------------------------------------------------------
28 // This QFunction sets up the geometric factor required for integration when
29 //   reference coordinates have a different dimension than the one of
30 //   physical coordinates
31 //
32 // Reference (parent) 2D coordinates: X \in [-1, 1]^2
33 //
34 // Global physical coordinates given by the mesh (3D): xx \in [-l, l]^3
35 //
36 // Local physical coordinates on the manifold (2D): x \in [-l, l]^2
37 //
38 // Change of coordinates matrix computed by the library:
39 //   (physical 3D coords relative to reference 2D coords)
40 //   dxx_j/dX_i (indicial notation) [3 * 2]
41 //
42 // Change of coordinates x (physical 2D) relative to xx (phyisical 3D):
43 //   dx_i/dxx_j (indicial notation) [2 * 3]
44 //
45 // Change of coordinates x (physical 2D) relative to X (reference 2D):
46 //   (by chain rule)
47 //   dx_i/dX_j = dx_i/dxx_k * dxx_k/dX_j
48 //
49 // The quadrature data is stored in the array q_data.
50 //
51 // We require the determinant of the Jacobian to properly compute integrals of
52 //   the form: int( u v )
53 //
54 // Qdata: w * det(dx_i/dX_j)
55 //
56 // -----------------------------------------------------------------------------
57 CEED_QFUNCTION(SetupMassGeoCube)(void *ctx, const CeedInt Q,
58                              const CeedScalar *const *in,
59                              CeedScalar *const *out) {
60   // Inputs
61   const CeedScalar *J = in[1], *w = in[2];
62   // Outputs
63   CeedScalar *q_data = out[0];
64 
65   // Quadrature Point Loop
66   CeedPragmaSIMD
67   for (CeedInt i=0; i<Q; i++) {
68     // Read dxxdX Jacobian entries, stored as
69     // 0 3
70     // 1 4
71     // 2 5
72     const CeedScalar dxxdX[3][2] = {{J[i+Q*0],
73                                      J[i+Q*3]},
74                                     {J[i+Q*1],
75                                      J[i+Q*4]},
76                                     {J[i+Q*2],
77                                      J[i+Q*5]}
78                                    };
79 
80     // Modulus of dxxdX column vectors
81     const CeedScalar mod_g_1 = sqrt(dxxdX[0][0]*dxxdX[0][0] +
82                                     dxxdX[1][0]*dxxdX[1][0] +
83                                     dxxdX[2][0]*dxxdX[2][0]);
84     const CeedScalar mod_g_2 = sqrt(dxxdX[0][1]*dxxdX[0][1] +
85                                     dxxdX[1][1]*dxxdX[1][1] +
86                                     dxxdX[2][1]*dxxdX[2][1]);
87 
88     // Use normalized column vectors of dxxdX as rows of dxdxx
89     const CeedScalar dxdxx[2][3] = {{dxxdX[0][0] / mod_g_1,
90                                      dxxdX[1][0] / mod_g_1,
91                                      dxxdX[2][0] / mod_g_1},
92                                     {dxxdX[0][1] / mod_g_2,
93                                      dxxdX[1][1] / mod_g_2,
94                                      dxxdX[2][1] / mod_g_2}
95                                    };
96 
97     CeedScalar dxdX[2][2];
98     for (int j=0; j<2; j++)
99       for (int k=0; k<2; k++) {
100         dxdX[j][k] = 0;
101         for (int l=0; l<3; l++)
102           dxdX[j][k] += dxdxx[j][l]*dxxdX[l][k];
103       }
104 
105     q_data[i+Q*0] = (dxdX[0][0]*dxdX[1][1] - dxdX[1][0]*dxdX[0][1]) * w[i];
106 
107   } // End of Quadrature Point Loop
108   return 0;
109 }
110 
111 // -----------------------------------------------------------------------------
112 // This QFunction applies the mass operator for a scalar field.
113 //
114 // Inputs:
115 //   u     - Input vector at quadrature points
116 //   q_data - Geometric factors
117 //
118 // Output:
119 //   v     - Output vector (test function) at quadrature points
120 //
121 // -----------------------------------------------------------------------------
122 CEED_QFUNCTION(Mass)(void *ctx, const CeedInt Q,
123                      const CeedScalar *const *in, CeedScalar *const *out) {
124   // Inputs
125   const CeedScalar *u = in[0], *q_data = in[1];
126   // Outputs
127   CeedScalar *v = out[0];
128 
129   // Quadrature Point Loop
130   CeedPragmaSIMD
131   for (CeedInt i=0; i<Q; i++)
132     v[i] = q_data[i] * u[i];
133 
134   return 0;
135 }
136 // -----------------------------------------------------------------------------
137 
138 #endif // areacube_h
139