CEED
diff --git a/‎examples/ceed/ex2-surface-f-c.h‎
Lines changed: 136 additions & 0 deletions b/‎examples/ceed/ex2-surface-f-c.h‎
Lines changed: 136 additions & 0 deletions
@@ -0,0 +1,136 @@
+// Copyright (c) 2017-2026, Lawrence Livermore National Security, LLC and other CEED contributors.
+// All Rights Reserved. See the top-level LICENSE and NOTICE files for details.
+//
+// SPDX-License-Identifier: BSD-2-Clause
+//
+// This file is part of CEED:  http://github.com/ceed
+
+#include <ceed/types.h>
+
+/// libCEED Q-function for building quadrature data for a diffusion operator
+CEED_QFUNCTION(build_diff)(void *ctx, const CeedInt Q, const CeedScalar *const *in, CeedScalar *const *out) {
+  const long dim       = ((const long *)ctx)[0];
+  const long space_dim = ((const long *)ctx)[1];
+
+  // in[0] is Jacobians with shape [dim, dim, Q]
+  // in[1] is quadrature weights, size (Q)
+  const CeedScalar *w             = in[1];
+  CeedScalar(*q_data)[CEED_Q_VLA] = (CeedScalar(*)[CEED_Q_VLA])out[0];
+
+  // At every quadrature point, compute w/det(J).adj(J).adj(J)^T and store
+  // the symmetric part of the result.
+  switch (dim + 10 * space_dim) {
+    case 11: {
+      const CeedScalar(*J)[1][CEED_Q_VLA] = (const CeedScalar(*)[1][CEED_Q_VLA])in[0];
+
+      CeedPragmaSIMD for (CeedInt i = 0; i < Q; i++) { q_data[0][i] = w[i] / J[0][0][i]; }  // End of Quadrature Point Loop
+    } break;
+    case 22: {
+      const CeedScalar(*J)[2][CEED_Q_VLA] = (const CeedScalar(*)[2][CEED_Q_VLA])in[0];
+
+      CeedPragmaSIMD for (CeedInt i = 0; i < Q; i++) {
+        // J: 0 2   q_data: 0 2   adj(J):  J11 -J01
+        //    1 3           2 1           -J10  J00
+        const CeedScalar J00 = J[0][0][i];
+        const CeedScalar J10 = J[0][1][i];
+        const CeedScalar J01 = J[1][0][i];
+        const CeedScalar J11 = J[1][1][i];
+        const CeedScalar qw  = w[i] / (J00 * J11 - J10 * J01);
+
+        q_data[0][i] = qw * (J01 * J01 + J11 * J11);
+        q_data[1][i] = qw * (J00 * J00 + J10 * J10);
+        q_data[2][i] = -qw * (J00 * J01 + J10 * J11);
+      }  // End of Quadrature Point Loop
+    } break;
+    case 33: {
+      const CeedScalar(*J)[3][CEED_Q_VLA] = (const CeedScalar(*)[3][CEED_Q_VLA])in[0];
+
+      CeedPragmaSIMD for (CeedInt i = 0; i < Q; i++) {
+        // Compute the adjoint
+        CeedScalar A[3][3];
+
+        for (CeedInt j = 0; j < 3; j++) {
+          for (CeedInt k = 0; k < 3; k++) {
+            // Equivalent code with J as a VLA and no mod operations:
+            // A[k][j] = J[j+1][k+1]*J[j+2][k+2] - J[j+1][k+2]*J[j+2][k+1]
+            A[k][j] =
+                J[(k + 1) % 3][(j + 1) % 3][i] * J[(k + 2) % 3][(j + 2) % 3][i] - J[(k + 2) % 3][(j + 1) % 3][i] * J[(k + 1) % 3][(j + 2) % 3][i];
+          }
+        }
+
+        // Compute quadrature weight / det(J)
+        const CeedScalar qw = w[i] / (J[0][0][i] * A[0][0] + J[0][1][i] * A[0][1] + J[0][2][i] * A[0][2]);
+
+        // Compute geometric factors
+        // Stored in Voigt convention
+        // 0 5 4
+        // 5 1 3
+        // 4 3 2
+        q_data[0][i] = qw * (A[0][0] * A[0][0] + A[0][1] * A[0][1] + A[0][2] * A[0][2]);
+        q_data[1][i] = qw * (A[1][0] * A[1][0] + A[1][1] * A[1][1] + A[1][2] * A[1][2]);
+        q_data[2][i] = qw * (A[2][0] * A[2][0] + A[2][1] * A[2][1] + A[2][2] * A[2][2]);
+        q_data[3][i] = qw * (A[1][0] * A[2][0] + A[1][1] * A[2][1] + A[1][2] * A[2][2]);
+        q_data[4][i] = qw * (A[0][0] * A[2][0] + A[0][1] * A[2][1] + A[0][2] * A[2][2]);
+        q_data[5][i] = qw * (A[0][0] * A[1][0] + A[0][1] * A[1][1] + A[0][2] * A[1][2]);
+      }  // End of Quadrature Point Loop
+    } break;
+  }
+  return CEED_ERROR_SUCCESS;
+}
+
+/// libCEED Q-function for applying a diff operator
+CEED_QFUNCTION(apply_diff)(void *ctx, const CeedInt Q, const CeedScalar *const *in, CeedScalar *const *out) {
+  const long dim = ((const long *)ctx)[0];
+
+  // in[0], out[0] solution gradients with shape [dim, 1, Q]
+  // in[1] is quadrature data with shape [num_components, Q]
+  const CeedScalar(*q_data)[CEED_Q_VLA] = (const CeedScalar(*)[CEED_Q_VLA])in[1];
+
+  switch (dim) {
+    case 1: {
+      const CeedScalar *ug = in[0];
+      CeedScalar       *vg = out[0];
+
+      CeedPragmaSIMD for (CeedInt i = 0; i < Q; i++) { vg[i] = ug[i] * q_data[0][i]; }  // End of Quadrature Point Loop
+    } break;
+    case 2: {
+      const CeedScalar(*ug)[CEED_Q_VLA] = (const CeedScalar(*)[CEED_Q_VLA])in[0];
+      CeedScalar(*vg)[CEED_Q_VLA]       = (CeedScalar(*)[CEED_Q_VLA])out[0];
+
+      CeedPragmaSIMD for (CeedInt i = 0; i < Q; i++) {
+        // Read q_data (dXdxdXdx_T symmetric matrix)
+        // Stored in Voigt convention
+        // 0 2
+        // 2 1
+        const CeedScalar dXdxdXdx_T[2][2] = {
+            {q_data[0][i], q_data[2][i]},
+            {q_data[2][i], q_data[1][i]}
+        };
+
+        // j = direction of vg
+        for (int j = 0; j < 2; j++) vg[j][i] = (ug[0][i] * dXdxdXdx_T[0][j] + ug[1][i] * dXdxdXdx_T[1][j]);
+      }  // End of Quadrature Point Loop
+    } break;
+    case 3: {
+      const CeedScalar(*ug)[CEED_Q_VLA] = (const CeedScalar(*)[CEED_Q_VLA])in[0];
+      CeedScalar(*vg)[CEED_Q_VLA]       = (CeedScalar(*)[CEED_Q_VLA])out[0];
+
+      CeedPragmaSIMD for (CeedInt i = 0; i < Q; i++) {
+        // Read q_data (dXdxdXdx_T symmetric matrix)
+        // Stored in Voigt convention
+        // 0 5 4
+        // 5 1 3
+        // 4 3 2
+        const CeedScalar dXdxdXdx_T[3][3] = {
+            {q_data[0][i], q_data[5][i], q_data[4][i]},
+            {q_data[5][i], q_data[1][i], q_data[3][i]},
+            {q_data[4][i], q_data[3][i], q_data[2][i]}
+        };
+
+        // j = direction of vg
+        for (int j = 0; j < 3; j++) vg[j][i] = (ug[0][i] * dXdxdXdx_T[0][j] + ug[1][i] * dXdxdXdx_T[1][j] + ug[2][i] * dXdxdXdx_T[2][j]);
+      }  // End of Quadrature Point Loop
+    } break;
+  }
+  return CEED_ERROR_SUCCESS;
+}