67 …HELPER void CalcRot(const CeedScalar *A, CeedInt N, CeedInt i, CeedInt j, CeedScalar *rotmat_cst) {  in CalcRot()  argument
68   rotmat_cst[2]      = 1.0;  // = tan(θ)  in CalcRot()
73     rotmat_cst[2]    = 0.0;  in CalcRot()
79       rotmat_cst[2] = 1.0 / (sqrt(1 + kappa * kappa) + fabs(kappa));  in CalcRot()
80       if (kappa < 0.0) rotmat_cst[2] = -rotmat_cst[2];  in CalcRot()
83   rotmat_cst[0] = 1.0 / sqrt(1 + rotmat_cst[2] * rotmat_cst[2]);  in CalcRot()
84   rotmat_cst[1] = rotmat_cst[0] * rotmat_cst[2];  in CalcRot()
155 …Rot(CeedScalar *A, CeedInt N, CeedInt i, CeedInt j, CeedInt *max_idx_row, CeedScalar *rotmat_cst) {  in ApplyRot()  argument
157   A[i * N + i] -= rotmat_cst[2] * A[i * N + j];  in ApplyRot()
158   A[j * N + j] += rotmat_cst[2] * A[i * N + j];  in ApplyRot()
170 …A[w * N + i] = rotmat_cst[0] * A[w * N + i] - rotmat_cst[1] * A[w * N + j];  // A[w][i], A[w][j] f…  in ApplyRot()
176 …A[i * N + w] = rotmat_cst[0] * A[i * N + w] - rotmat_cst[1] * A[w * N + j];  // A[i][w], A[w][j] f…  in ApplyRot()
180 …A[i * N + w] = rotmat_cst[0] * A[i * N + w] - rotmat_cst[1] * A[j * N + w];  // A[i][w], A[j][w] f…  in ApplyRot()
188 …A[w * N + j] = rotmat_cst[1] * A[i * N + w] + rotmat_cst[0] * A[w * N + j];  // A[i][w], A[w][j] f…  in ApplyRot()
193 …A[w * N + j] = rotmat_cst[1] * A[w * N + i] + rotmat_cst[0] * A[w * N + j];  // A[w][i], A[w][j] f…  in ApplyRot()
198 …A[j * N + w] = rotmat_cst[1] * A[w * N + i] + rotmat_cst[0] * A[j * N + w];  // A[w][i], A[j][w] f…  in ApplyRot()
214 …_HELPER void ApplyRotLeft(CeedScalar *A, CeedInt N, CeedInt i, CeedInt j, CeedScalar *rotmat_cst) {  in ApplyRotLeft()  argument
218     A[i * N + v]   = rotmat_cst[0] * A[i * N + v] - rotmat_cst[1] * A[j * N + v];  in ApplyRotLeft()
219     A[j * N + v]   = rotmat_cst[1] * Aiv + rotmat_cst[0] * A[j * N + v];  in ApplyRotLeft()
279   CeedScalar rotmat_cst[3] = {0.};  // cos(θ), sin(θ), and tan(θ),  in Diagonalize()  local
302 …CalcRot(A, N, i, j, rotmat_cst);                // Calculate the parameters of the rotation matrix.  in Diagonalize()
303     ApplyRot(A, N, i, j, max_idx_row, rotmat_cst);  // Apply this rotation to the A matrix.  in Diagonalize()
304     if (calc_evec) ApplyRotLeft(evec, N, i, j, rotmat_cst);  in Diagonalize()