xref: /libCEED/examples/mfem/bp3.h (revision a0154adecfab8547cdc0febbbf40ac009dbe9d1d)
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 #ifndef bp3_h
9 #define bp3_h
10 
11 /// A structure used to pass additional data to f_build_diff and f_apply_diff
12 struct BuildContext { CeedInt dim, space_dim; };
13 
14 /// libCEED Q-function for building quadrature data for a diffusion operator
15 CEED_QFUNCTION(f_build_diff)(void *ctx, const CeedInt Q,
16                              const CeedScalar *const *in, CeedScalar *const *out) {
17   BuildContext *bc = (BuildContext *)ctx;
18   // in[0] is Jacobians with shape [dim, nc=dim, Q]
19   // in[1] is quadrature weights, size (Q)
20   //
21   // At every quadrature point, compute w/det(J).adj(J).adj(J)^T and store
22   // the symmetric part of the result.
23   const CeedScalar *J = in[0], *w = in[1];
24   CeedScalar *qdata = out[0];
25 
26   switch (bc->dim + 10*bc->space_dim) {
27   case 11:
28     // Quadrature Point Loop
29     CeedPragmaSIMD
30     for (CeedInt i=0; i<Q; i++) {
31       qdata[i] = w[i] / J[i];
32     }
33     break;
34   case 22:
35     // Quadrature Point Loop
36     CeedPragmaSIMD
37     for (CeedInt i=0; i<Q; i++) {
38       // J: 0 2   qdata: 0 2   adj(J):  J22 -J12
39       //    1 3          2 1           -J21  J11
40       const CeedScalar J11 = J[i+Q*0];
41       const CeedScalar J21 = J[i+Q*1];
42       const CeedScalar J12 = J[i+Q*2];
43       const CeedScalar J22 = J[i+Q*3];
44       const CeedScalar qw = w[i] / (J11*J22 - J21*J12);
45       qdata[i+Q*0] =   qw * (J12*J12 + J22*J22);
46       qdata[i+Q*1] =   qw * (J11*J11 + J21*J21);
47       qdata[i+Q*2] = - qw * (J11*J12 + J21*J22);
48     }
49     break;
50   case 33:
51     // Quadrature Point Loop
52     CeedPragmaSIMD
53     for (CeedInt i=0; i<Q; i++) {
54       // J: 0 3 6   qdata: 0 5 4
55       //    1 4 7          5 1 3
56       //    2 5 8          4 3 2
57       const CeedScalar J11 = J[i+Q*0];
58       const CeedScalar J21 = J[i+Q*1];
59       const CeedScalar J31 = J[i+Q*2];
60       const CeedScalar J12 = J[i+Q*3];
61       const CeedScalar J22 = J[i+Q*4];
62       const CeedScalar J32 = J[i+Q*5];
63       const CeedScalar J13 = J[i+Q*6];
64       const CeedScalar J23 = J[i+Q*7];
65       const CeedScalar J33 = J[i+Q*8];
66       const CeedScalar A11 = J22*J33 - J23*J32;
67       const CeedScalar A12 = J13*J32 - J12*J33;
68       const CeedScalar A13 = J12*J23 - J13*J22;
69       const CeedScalar A21 = J23*J31 - J21*J33;
70       const CeedScalar A22 = J11*J33 - J13*J31;
71       const CeedScalar A23 = J13*J21 - J11*J23;
72       const CeedScalar A31 = J21*J32 - J22*J31;
73       const CeedScalar A32 = J12*J31 - J11*J32;
74       const CeedScalar A33 = J11*J22 - J12*J21;
75       const CeedScalar qw = w[i] / (J11*A11 + J21*A12 + J31*A13);
76       qdata[i+Q*0] = qw * (A11*A11 + A12*A12 + A13*A13);
77       qdata[i+Q*1] = qw * (A21*A21 + A22*A22 + A23*A23);
78       qdata[i+Q*2] = qw * (A31*A31 + A32*A32 + A33*A33);
79       qdata[i+Q*3] = qw * (A21*A31 + A22*A32 + A23*A33);
80       qdata[i+Q*4] = qw * (A11*A31 + A12*A32 + A13*A33);
81       qdata[i+Q*5] = qw * (A11*A21 + A12*A22 + A13*A23);
82     }
83     break;
84   }
85   return 0;
86 }
87 
88 /// libCEED Q-function for applying a diff operator
89 CEED_QFUNCTION(f_apply_diff)(void *ctx, const CeedInt Q,
90                              const CeedScalar *const *in, CeedScalar *const *out) {
91   BuildContext *bc = (BuildContext *)ctx;
92   // in[0], out[0] have shape [dim, nc=1, Q]
93   const CeedScalar *ug = in[0], *qdata = in[1];
94   CeedScalar *vg = out[0];
95 
96   switch (bc->dim) {
97   case 1:
98     // Quadrature Point Loop
99     CeedPragmaSIMD
100     for (CeedInt i=0; i<Q; i++) {
101       vg[i] = ug[i] * qdata[i];
102     }
103     break;
104   case 2:
105     // Quadrature Point Loop
106     CeedPragmaSIMD
107     for (CeedInt i=0; i<Q; i++) {
108       const CeedScalar ug0 = ug[i+Q*0];
109       const CeedScalar ug1 = ug[i+Q*1];
110       vg[i+Q*0] = qdata[i+Q*0]*ug0 + qdata[i+Q*2]*ug1;
111       vg[i+Q*1] = qdata[i+Q*2]*ug0 + qdata[i+Q*1]*ug1;
112     }
113     break;
114   case 3:
115     // Quadrature Point Loop
116     CeedPragmaSIMD
117     for (CeedInt i=0; i<Q; i++) {
118       const CeedScalar ug0 = ug[i+Q*0];
119       const CeedScalar ug1 = ug[i+Q*1];
120       const CeedScalar ug2 = ug[i+Q*2];
121       vg[i+Q*0] = qdata[i+Q*0]*ug0 + qdata[i+Q*5]*ug1 + qdata[i+Q*4]*ug2;
122       vg[i+Q*1] = qdata[i+Q*5]*ug0 + qdata[i+Q*1]*ug1 + qdata[i+Q*3]*ug2;
123       vg[i+Q*2] = qdata[i+Q*4]*ug0 + qdata[i+Q*3]*ug1 + qdata[i+Q*2]*ug2;
124     }
125     break;
126   }
127   return 0;
128 }
129 
130 #endif // bp3_h
131