xref: /honee/qfunctions/setupgeo_helpers.h (revision 4d9179f22426c0d7d449235bba4b91193b974d74)
1 // SPDX-FileCopyrightText: Copyright (c) 2017-2024, HONEE contributors.
2 // SPDX-License-Identifier: Apache-2.0 OR BSD-2-Clause
3 
4 /// @file
5 /// Geometric factors (3D) for HONEE
6 #pragma once
7 
8 #include <ceed/types.h>
9 #include "utils.h"
10 
11 /**
12  * @brief Calculate dXdx from dxdX for 3D elements
13  *
14  * Reference (parent) coordinates: X
15  * Physical (current) coordinates: x
16  * Change of coordinate matrix: dxdX_{i,j} = x_{i,j} (indicial notation)
17  * Inverse of change of coordinate matrix: dXdx_{i,j} = (detJ^-1) * X_{i,j}
18  *
19  * @param[in]  Q        Number of quadrature points
20  * @param[in]  i        Current quadrature point
21  * @param[in]  dxdX_q   Mapping Jacobian (gradient of the coordinate space)
22  * @param[out] dXdx     Inverse of mapping Jacobian at quadrature point i
23  * @param[out] detJ_ptr Determinate of the Jacobian, may be NULL is not desired
24  */
25 CEED_QFUNCTION_HELPER void InvertMappingJacobian_3D(CeedInt Q, CeedInt i, const CeedScalar (*dxdX_q)[3][CEED_Q_VLA], CeedScalar dXdx[3][3],
26                                                     CeedScalar *detJ_ptr) {
27   CeedScalar dxdX[3][3];
28 
29   GradUnpack3D(Q, i, 3, (CeedScalar *)dxdX_q, dxdX);
30   MatInv3(dxdX, dXdx, detJ_ptr);
31 }
32 
33 /**
34  * @brief Calculate dXdx from dxdX for 2D elements
35  *
36  * Reference (parent) coordinates: X
37  * Physical (current) coordinates: x
38  * Change of coordinate matrix: dxdX_{i,j} = x_{i,j} (indicial notation)
39  * Inverse of change of coordinate matrix: dXdx_{i,j} = (detJ^-1) * X_{i,j}
40  *
41  * @param[in]  Q        Number of quadrature points
42  * @param[in]  i        Current quadrature point
43  * @param[in]  dxdX_q   Mapping Jacobian (gradient of the coordinate space)
44  * @param[out] dXdx     Inverse of mapping Jacobian at quadrature point i
45  * @param[out] detJ_ptr Determinate of the Jacobian, may be NULL is not desired
46  */
47 CEED_QFUNCTION_HELPER void InvertMappingJacobian_2D(CeedInt Q, CeedInt i, const CeedScalar (*dxdX_q)[2][CEED_Q_VLA], CeedScalar dXdx[2][2],
48                                                     CeedScalar *detJ_ptr) {
49   CeedScalar dxdX[2][2];
50 
51   GradUnpack2D(Q, i, 2, (CeedScalar *)dxdX_q, dxdX);
52   MatInv2(dxdX, dXdx, detJ_ptr);
53 }
54 
55 /**
56  * @brief Calculate face element's normal vector from dxdX
57  *
58  * Reference (parent) 2D coordinates: X
59  * Physical (current) 3D coordinates: x
60  * Change of coordinate matrix:
61  *   dxdX_{i,j} = dx_i/dX_j (indicial notation) [3 * 2]
62  * Inverse change of coordinate matrix:
63  *   dXdx_{i,j} = dX_i/dx_j (indicial notation) [2 * 3]
64  *
65  * (N1,N2,N3) is given by the cross product of the columns of dxdX_{i,j}
66  *
67  * detJb is the magnitude of (N1,N2,N3)
68  *
69  * Normal vector = (N1,N2,N3) / detJb
70  *
71  * @param[in]  Q        Number of quadrature points
72  * @param[in]  i        Current quadrature point
73  * @param[in]  dxdX_q   Mapping Jacobian (gradient of the coordinate space)
74  * @param[out] normal   Inverse of mapping Jacobian at quadrature point i
75  * @param[out] detJ_ptr Determinate of the Jacobian, may be NULL is not desired
76  */
77 CEED_QFUNCTION_HELPER void NormalVectorFromdxdX_3D(CeedInt Q, CeedInt i, const CeedScalar (*dxdX_q)[3][CEED_Q_VLA], CeedScalar normal[3],
78                                                    CeedScalar *detJ_ptr) {
79   CeedScalar dxdX[3][2];
80 
81   GradUnpack2D(Q, i, 3, (CeedScalar *)dxdX_q, dxdX);
82   // N1, N2, and N3 are given by the cross product of the columns of dxdX
83   normal[0] = dxdX[1][0] * dxdX[2][1] - dxdX[2][0] * dxdX[1][1];
84   normal[1] = dxdX[2][0] * dxdX[0][1] - dxdX[0][0] * dxdX[2][1];
85   normal[2] = dxdX[0][0] * dxdX[1][1] - dxdX[1][0] * dxdX[0][1];
86 
87   const CeedScalar detJ = Norm3(normal);
88   ScaleN(normal, 1 / detJ, 3);
89   if (detJ_ptr) *detJ_ptr = detJ;
90 }
91 
92 /**
93  * This QFunction sets up the geometric factor required for integration when reference coordinates are in 1D and the physical coordinates are in 2D
94  *
95  * Reference (parent) 1D coordinates: X
96  * Physical (current) 2D coordinates: x
97  * Change of coordinate vector:
98  *           N1 = dx_1/dX
99  *           N2 = dx_2/dX
100  *
101  * detJb is the magnitude of (N1,N2)
102  *
103  * We require the determinant of the Jacobian to properly compute integrals of the form: int( u v )
104  *
105  * Normal vector is given by the cross product of (N1,N2)/detJ and ẑ
106  *
107  * @param[in]  Q        Number of quadrature points
108  * @param[in]  i        Current quadrature point
109  * @param[in]  dxdX_q   Mapping Jacobian (gradient of the coordinate space)
110  * @param[out] normal   Inverse of mapping Jacobian at quadrature point i
111  * @param[out] detJ_ptr Determinate of the Jacobian, may be NULL is not desired
112  */
113 CEED_QFUNCTION_HELPER void NormalVectorFromdxdX_2D(CeedInt Q, CeedInt i, const CeedScalar (*dxdX_q)[CEED_Q_VLA], CeedScalar normal[2],
114                                                    CeedScalar *detJ_ptr) {
115   normal[0]              = dxdX_q[1][i];
116   normal[1]              = -dxdX_q[0][i];
117   const CeedScalar detJb = Norm2(normal);
118   ScaleN(normal, 1 / detJb, 2);
119   if (detJ_ptr) *detJ_ptr = detJb;
120 }
121 
122 /**
123  * @brief Calculate inverse of mapping Jacobian, (dxdX)^-1
124  *
125  * Reference (parent) 2D coordinates: X
126  * Physical (current) 3D coordinates: x
127  * Change of coordinate matrix:
128  *   dxdX_{i,j} = dx_i/dX_j (indicial notation) [3 * 2]
129  * Inverse change of coordinate matrix:
130  *   dXdx_{i,j} = dX_i/dx_j (indicial notation) [2 * 3]
131  *
132  * dXdx is calculated via Moore–Penrose inverse:
133  *
134  *   dX_i/dx_j = (dxdX^T dxdX)^(-1) dxdX
135  *             = (dx_l/dX_i * dx_l/dX_k)^(-1) dx_j/dX_k
136  *
137  * @param[in]  Q      Number of quadrature points
138  * @param[in]  i      Current quadrature point
139  * @param[in]  dxdX_q Mapping Jacobian (gradient of the coordinate space)
140  * @param[out] dXdx   Inverse of mapping Jacobian at quadrature point i
141  */
142 CEED_QFUNCTION_HELPER void InvertBoundaryMappingJacobian_3D(CeedInt Q, CeedInt i, const CeedScalar (*dxdX_q)[3][CEED_Q_VLA], CeedScalar dXdx[2][3]) {
143   CeedScalar dxdX[3][2];
144   GradUnpack2D(Q, i, 3, (CeedScalar *)dxdX_q, dxdX);
145 
146   // dxdX_k,j * dxdX_j,k
147   CeedScalar dxdXTdxdX[2][2] = {{0.}};
148   for (CeedInt j = 0; j < 2; j++) {
149     for (CeedInt k = 0; k < 2; k++) {
150       for (CeedInt l = 0; l < 3; l++) dxdXTdxdX[j][k] += dxdX[l][j] * dxdX[l][k];
151     }
152   }
153 
154   const CeedScalar detdxdXTdxdX = dxdXTdxdX[0][0] * dxdXTdxdX[1][1] - dxdXTdxdX[1][0] * dxdXTdxdX[0][1];
155 
156   // Compute inverse of dxdXTdxdX
157   CeedScalar dxdXTdxdX_inv[2][2];
158   dxdXTdxdX_inv[0][0] = dxdXTdxdX[1][1] / detdxdXTdxdX;
159   dxdXTdxdX_inv[0][1] = -dxdXTdxdX[0][1] / detdxdXTdxdX;
160   dxdXTdxdX_inv[1][0] = -dxdXTdxdX[1][0] / detdxdXTdxdX;
161   dxdXTdxdX_inv[1][1] = dxdXTdxdX[0][0] / detdxdXTdxdX;
162 
163   // Compute dXdx from dxdXTdxdX^-1 and dxdX
164   for (CeedInt j = 0; j < 2; j++) {
165     for (CeedInt k = 0; k < 3; k++) {
166       dXdx[j][k] = 0;
167       for (CeedInt l = 0; l < 2; l++) dXdx[j][k] += dxdXTdxdX_inv[l][j] * dxdX[k][l];
168     }
169   }
170 }
171