| /* blas/source_rotmg.h |
| * |
| * Copyright (C) 1996, 1997, 1998, 1999, 2000 Brian Gough |
| * |
| * 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 BASE G = 4096.0, G2 = G * G; |
| BASE D1 = *d1, D2 = *d2, x = *b1, y = b2; |
| BASE h11, h12, h21, h22, u; |
| |
| BASE c, s; |
| |
| /* case of d1 < 0, appendix A, second to last paragraph */ |
| |
| if (D1 < 0.0) { |
| P[0] = -1; |
| P[1] = 0; |
| P[2] = 0; |
| P[3] = 0; |
| P[4] = 0; |
| *d1 = 0; |
| *d2 = 0; |
| *b1 = 0; |
| return; |
| } |
| |
| if (D2 * y == 0.0) { |
| P[0] = -2; /* case of H = I, page 315 */ |
| return; |
| } |
| |
| c = fabs(D1 * x * x); |
| s = fabs(D2 * y * y); |
| |
| if (c > s) { |
| /* case of equation A6 */ |
| |
| P[0] = 0.0; |
| |
| h11 = 1; |
| h12 = (D2 * y) / (D1 * x); |
| h21 = -y / x; |
| h22 = 1; |
| |
| u = 1 - h21 * h12; |
| |
| if (u <= 0.0) { /* the case u <= 0 is rejected */ |
| P[0] = -1; |
| P[1] = 0; |
| P[2] = 0; |
| P[3] = 0; |
| P[4] = 0; |
| *d1 = 0; |
| *d2 = 0; |
| *b1 = 0; |
| return; |
| } |
| |
| D1 /= u; |
| D2 /= u; |
| x *= u; |
| } else { |
| /* case of equation A7 */ |
| |
| if (D2 * y * y < 0.0) { |
| P[0] = -1; |
| P[1] = 0; |
| P[2] = 0; |
| P[3] = 0; |
| P[4] = 0; |
| *d1 = 0; |
| *d2 = 0; |
| *b1 = 0; |
| return; |
| } |
| |
| P[0] = 1; |
| |
| h11 = (D1 * x) / (D2 * y); |
| h12 = 1; |
| h21 = -1; |
| h22 = x / y; |
| |
| u = 1 + h11 * h22; |
| |
| D1 /= u; |
| D2 /= u; |
| |
| { |
| BASE tmp = D2; |
| D2 = D1; |
| D1 = tmp; |
| } |
| |
| x = y * u; |
| } |
| |
| /* rescale D1 to range [1/G2,G2] */ |
| |
| while (D1 <= 1.0 / G2 && D1 != 0.0) { |
| P[0] = -1; |
| D1 *= G2; |
| x /= G; |
| h11 /= G; |
| h12 /= G; |
| } |
| |
| while (D1 >= G2) { |
| P[0] = -1; |
| D1 /= G2; |
| x *= G; |
| h11 *= G; |
| h12 *= G; |
| } |
| |
| /* rescale D2 to range [1/G2,G2] */ |
| |
| while (fabs(D2) <= 1.0 / G2 && D2 != 0.0) { |
| P[0] = -1; |
| D2 *= G2; |
| h21 /= G; |
| h22 /= G; |
| } |
| |
| while (fabs(D2) >= G2) { |
| P[0] = -1; |
| D2 /= G2; |
| h21 *= G; |
| h22 *= G; |
| } |
| |
| *d1 = D1; |
| *d2 = D2; |
| *b1 = x; |
| |
| if (P[0] == -1.0) { |
| P[1] = h11; |
| P[2] = h21; |
| P[3] = h12; |
| P[4] = h22; |
| } else if (P[0] == 0.0) { |
| P[2] = h21; |
| P[3] = h12; |
| } else if (P[0] == 1.0) { |
| P[1] = h11; |
| P[4] = h22; |
| } |
| } |