| /* blas/source_tbsv_r.h |
| * |
| * Copyright (C) 1996, 1997, 1998, 1999, 2000 Gerard Jungman |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or (at |
| * your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, but |
| * WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
| */ |
| |
| { |
| const int nonunit = (Diag == CblasNonUnit); |
| INDEX i, j; |
| const int Trans = (TransA != CblasConjTrans) ? TransA : CblasTrans; |
| |
| if (N == 0) |
| return; |
| |
| /* form x := inv( A )*x */ |
| |
| if ((order == CblasRowMajor && Trans == CblasNoTrans && Uplo == CblasUpper) |
| || (order == CblasColMajor && Trans == CblasTrans && Uplo == CblasLower)) { |
| /* backsubstitution */ |
| INDEX ix = OFFSET(N, incX) + incX * (N - 1); |
| for (i = N; i > 0 && i--;) { |
| BASE tmp = X[ix]; |
| const INDEX j_min = i + 1; |
| const INDEX j_max = GSL_MIN(N, i + K + 1); |
| INDEX jx = OFFSET(N, incX) + j_min * incX; |
| for (j = j_min; j < j_max; j++) { |
| const BASE Aij = A[lda * i + (j - i)]; |
| tmp -= Aij * X[jx]; |
| jx += incX; |
| } |
| if (nonunit) { |
| X[ix] = tmp / A[lda * i + 0]; |
| } else { |
| X[ix] = tmp; |
| } |
| ix -= incX; |
| } |
| } else if ((order == CblasRowMajor && Trans == CblasNoTrans && Uplo == CblasLower) |
| || (order == CblasColMajor && Trans == CblasTrans && Uplo == CblasUpper)) { |
| |
| /* forward substitution */ |
| INDEX ix = OFFSET(N, incX); |
| |
| for (i = 0; i < N; i++) { |
| BASE tmp = X[ix]; |
| const INDEX j_min = (i > K ? i - K : 0); |
| const INDEX j_max = i; |
| INDEX jx = OFFSET(N, incX) + j_min * incX; |
| for (j = j_min; j < j_max; j++) { |
| const BASE Aij = A[lda * i + (K + j - i)]; |
| tmp -= Aij * X[jx]; |
| jx += incX; |
| } |
| if (nonunit) { |
| X[ix] = tmp / A[lda * i + K]; |
| } else { |
| X[ix] = tmp; |
| } |
| ix += incX; |
| } |
| } else if ((order == CblasRowMajor && Trans == CblasTrans && Uplo == CblasUpper) |
| || (order == CblasColMajor && Trans == CblasNoTrans && Uplo == CblasLower)) { |
| |
| /* form x := inv( A' )*x */ |
| |
| /* forward substitution */ |
| INDEX ix = OFFSET(N, incX); |
| for (i = 0; i < N; i++) { |
| BASE tmp = X[ix]; |
| const INDEX j_min = (K > i ? 0 : i - K); |
| const INDEX j_max = i; |
| INDEX jx = OFFSET(N, incX) + j_min * incX; |
| for (j = j_min; j < j_max; j++) { |
| const BASE Aji = A[(i - j) + lda * j]; |
| tmp -= Aji * X[jx]; |
| jx += incX; |
| } |
| if (nonunit) { |
| X[ix] = tmp / A[0 + lda * i]; |
| } else { |
| X[ix] = tmp; |
| } |
| ix += incX; |
| } |
| } else if ((order == CblasRowMajor && Trans == CblasTrans && Uplo == CblasLower) |
| || (order == CblasColMajor && Trans == CblasNoTrans && Uplo == CblasUpper)) { |
| |
| /* backsubstitution */ |
| INDEX ix = OFFSET(N, incX) + (N - 1) * incX; |
| for (i = N; i > 0 && i--;) { |
| BASE tmp = X[ix]; |
| const INDEX j_min = i + 1; |
| const INDEX j_max = GSL_MIN(N, i + K + 1); |
| INDEX jx = OFFSET(N, incX) + j_min * incX; |
| for (j = j_min; j < j_max; j++) { |
| const BASE Aji = A[(K + i - j) + lda * j]; |
| tmp -= Aji * X[jx]; |
| jx += incX; |
| } |
| if (nonunit) { |
| X[ix] = tmp / A[K + lda * i]; |
| } else { |
| X[ix] = tmp; |
| } |
| ix -= incX; |
| } |
| } else { |
| BLAS_ERROR("unrecognized operation"); |
| } |
| } |