xref: /libCEED/examples/petsc/qfunctions/area/areacube.h (revision dfffd4672647869dda6747969d7b7de9d0f03f3d)
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 __CUDACC__
21 #  include <math.h>
22 #endif
23 
24 // *****************************************************************************
25 // This QFunction sets up the geometric factor required for integration when
26 //   reference coordinates have a different dimension than the one of
27 //   pysical coordinates
28 //
29 // Reference (parent) 2D coordinates: X \in [-1, 1]^2
30 //
31 // Global physical coordinates given by the mesh (3D): xx \in [-l, l]^3
32 //
33 // Local physical coordinates on the manifold (2D): x \in [-l, l]^2
34 //
35 // Change of coordinates matrix computed by the library:
36 //   (pysical 3D coords relative to reference 2D coords)
37 //   dxx_j/dX_i (indicial notation) [3 * 2]
38 //
39 // Change of coordinates x (pysical 2D) relative to xx (phyisical 3D):
40 //   dx_i/dxx_j (indicial notation) [2 * 3]
41 //
42 // Change of coordinates x (physical 2D) relative to X (reference 2D):
43 //   (by chain rule)
44 //   dx_i/dX_j = dx_i/dxx_k * dxx_k/dX_j
45 //
46 // The quadrature data is stored in the array qdata.
47 //
48 // We require the determinant of the Jacobian to properly compute integrals of
49 //   the form: int( u v )
50 //
51 // Qdata: w * det(dx_i/dX_j)
52 //
53 // *****************************************************************************
54 
55 // -----------------------------------------------------------------------------
56 CEED_QFUNCTION(SetupMassGeoCube)(void *ctx, const CeedInt Q,
57                              const CeedScalar *const *in,
58                              CeedScalar *const *out) {
59   // Inputs
60   const CeedScalar *J = in[1], *w = in[2];
61   // Outputs
62   CeedScalar *qdata = out[0];
63 
64   // Quadrature Point Loop
65   CeedPragmaSIMD
66   for (CeedInt i=0; i<Q; i++) {
67     // Read dxxdX Jacobian entries, stored as
68     // 0 3
69     // 1 4
70     // 2 5
71     const CeedScalar dxxdX[3][2] = {{J[i+Q*0],
72                                      J[i+Q*3]},
73                                     {J[i+Q*1],
74                                      J[i+Q*4]},
75                                     {J[i+Q*2],
76                                      J[i+Q*5]}
77                                    };
78 
79     // Modulus of dxxdX column vectors
80     const CeedScalar modg1 = sqrt(dxxdX[0][0]*dxxdX[0][0] +
81                                   dxxdX[1][0]*dxxdX[1][0] +
82                                   dxxdX[2][0]*dxxdX[2][0]);
83     const CeedScalar modg2 = sqrt(dxxdX[0][1]*dxxdX[0][1] +
84                                   dxxdX[1][1]*dxxdX[1][1] +
85                                   dxxdX[2][1]*dxxdX[2][1]);
86 
87     // Use normalized column vectors of dxxdX as rows of dxdxx
88     const CeedScalar dxdxx[2][3] = {{dxxdX[0][0] / modg1,
89                                      dxxdX[1][0] / modg1,
90                                      dxxdX[2][0] / modg1},
91                                     {dxxdX[0][1] / modg2,
92                                      dxxdX[1][1] / modg2,
93                                      dxxdX[2][1] / modg2}
94                                    };
95 
96     CeedScalar dxdX[2][2];
97     for (int j=0; j<2; j++)
98       for (int k=0; k<2; k++) {
99         dxdX[j][k] = 0;
100         for (int l=0; l<3; l++)
101           dxdX[j][k] += dxdxx[j][l]*dxxdX[l][k];
102       }
103 
104     qdata[i+Q*0] = (dxdX[0][0]*dxdX[1][1] - dxdX[1][0]*dxdX[0][1]) * w[i];
105 
106   } // End of Quadrature Point Loop
107   return 0;
108 }
109 // -----------------------------------------------------------------------------
110 
111 // *****************************************************************************
112 // This QFunction applies the mass matrix for a scalar field.
113 //
114 // Inputs:
115 //   u     - Input vector at quadrature points
116 //   qdata - Geometric factors
117 //
118 // Output:
119 //   v     - Output vector (test function) at quadrature points
120 //
121 // *****************************************************************************
122 
123 // -----------------------------------------------------------------------------
124 CEED_QFUNCTION(Mass)(void *ctx, const CeedInt Q,
125                      const CeedScalar *const *in, CeedScalar *const *out) {
126   // Inputs
127   const CeedScalar *u = in[0], *qdata = in[1];
128   // Outputs
129   CeedScalar *v = out[0];
130 
131   // Quadrature Point Loop
132   CeedPragmaSIMD
133   for (CeedInt i=0; i<Q; i++)
134     v[i] = qdata[i] * u[i];
135 
136   return 0;
137 }
138 // -----------------------------------------------------------------------------
139