xref: /libCEED/examples/petsc/qfunctions/bps/bp1.h (revision d4d455536df293f3f9ba6a974c8a4079393bc3b8)
1 // Copyright (c) 2017-2022, Lawrence Livermore National Security, LLC and other CEED contributors.
2 // All Rights Reserved. See the top-level LICENSE and NOTICE files for details.
3 //
4 // SPDX-License-Identifier: BSD-2-Clause
5 //
6 // This file is part of CEED:  http://github.com/ceed
7 
8 /// @file
9 /// libCEED QFunctions for mass operator example using PETSc
10 
11 #ifndef bp1_h
12 #define bp1_h
13 
14 #include <ceed.h>
15 #include <math.h>
16 
17 // -----------------------------------------------------------------------------
18 // This QFunction sets up the geometric factors required to apply the
19 //   mass operator
20 //
21 // The quadrature data is stored in the array q_data.
22 //
23 // We require the determinant of the Jacobian to properly compute integrals of
24 //   the form: int( u v )
25 //
26 // Qdata: det_J * w
27 //
28 // -----------------------------------------------------------------------------
29 CEED_QFUNCTION(SetupMassGeo)(void *ctx, const CeedInt Q,
30                              const CeedScalar *const *in,
31                              CeedScalar *const *out) {
32   // Inputs
33   const CeedScalar(*J)[3][CEED_Q_VLA] = (const CeedScalar(*)[3][CEED_Q_VLA])in[1];
34   const CeedScalar(*w)                = in[2]; // Note: *X = in[0]
35   // Outputs
36   CeedScalar *q_data = out[0];
37 
38   const CeedInt dim = 3;
39   // Quadrature Point Loop
40   CeedPragmaSIMD
41   for (CeedInt i=0; i<Q; i++) {
42     // Setup
43     CeedScalar A[3][3];
44     for (CeedInt j = 0; j < dim; j++) {
45       for (CeedInt k = 0; k < dim; k++) {
46         // Equivalent code with no mod operations:
47         // A[k][j] = J[k+1][j+1]*J[k+2][j+2] - J[k+1][j+2]*J[k+2][j+1]
48         A[k][j] = J[(k + 1) % dim][(j + 1) % dim][i] * J[(k + 2) % dim][(j + 2) % dim][i] -
49                   J[(k + 1) % dim][(j + 2) % dim][i] * J[(k + 2) % dim][(j + 1) % dim][i];
50       }
51     }
52     const CeedScalar detJ = J[0][0][i] * A[0][0] + J[0][1][i] * A[0][1] + J[0][2][i] * A[0][2];
53     q_data[i] = detJ * w[i];
54   } // End of Quadrature Point Loop
55   return 0;
56 }
57 
58 // -----------------------------------------------------------------------------
59 // This QFunction sets up the rhs and true solution for the problem
60 // -----------------------------------------------------------------------------
61 CEED_QFUNCTION(SetupMassRhs)(void *ctx, const CeedInt Q,
62                              const CeedScalar *const *in,
63                              CeedScalar *const *out) {
64   const CeedScalar *x = in[0], *w = in[1];
65   CeedScalar *true_soln = out[0], *rhs = out[1];
66 
67   // Quadrature Point Loop
68   CeedPragmaSIMD
69   for (CeedInt i=0; i<Q; i++) {
70     true_soln[i] = sqrt(x[i]*x[i] + x[i+Q]*x[i+Q] + x[i+2*Q]*x[i+2*Q]);
71     rhs[i] = w[i] * true_soln[i];
72   } // End of Quadrature Point Loop
73   return 0;
74 }
75 
76 // -----------------------------------------------------------------------------
77 // This QFunction applies the mass operator for a scalar field.
78 //
79 // Inputs:
80 //   u     - Input vector at quadrature points
81 //   q_data - Geometric factors
82 //
83 // Output:
84 //   v     - Output vector (test functions) at quadrature points
85 //
86 // -----------------------------------------------------------------------------
87 CEED_QFUNCTION(Mass)(void *ctx, const CeedInt Q,
88                      const CeedScalar *const *in, CeedScalar *const *out) {
89   const CeedScalar *u = in[0], *q_data = in[1];
90   CeedScalar *v = out[0];
91 
92   // Quadrature Point Loop
93   CeedPragmaSIMD
94   for (CeedInt i=0; i<Q; i++)
95     v[i] = q_data[i] * u[i];
96 
97   return 0;
98 }
99 // -----------------------------------------------------------------------------
100 
101 #endif // bp1_h
102