Line data Source code
1 : /* Copyright (C) 2000-2019 The PARI group.
2 :
3 : This file is part of the PARI/GP package.
4 :
5 : PARI/GP is free software; you can redistribute it and/or modify it under the
6 : terms of the GNU General Public License as published by the Free Software
7 : Foundation; either version 2 of the License, or (at your option) any later
8 : version. It is distributed in the hope that it will be useful, but WITHOUT
9 : ANY WARRANTY WHATSOEVER.
10 :
11 : Check the License for details. You should have received a copy of it, along
12 : with the package; see the file 'COPYING'. If not, write to the Free Software
13 : Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */
14 :
15 : #include "pari.h"
16 : #include "paripriv.h"
17 :
18 : GEN
19 388511 : Flv_to_ZV(GEN x)
20 4096924 : { pari_APPLY_type(t_VEC, utoi(x[i])) }
21 :
22 : GEN
23 29589801 : Flc_to_ZC(GEN x)
24 252443722 : { pari_APPLY_type(t_COL, utoi(x[i])) }
25 :
26 : GEN
27 11486025 : Flm_to_ZM(GEN x)
28 40121868 : { pari_APPLY_type(t_MAT, Flc_to_ZC(gel(x,i))) }
29 :
30 : GEN
31 14 : Flc_to_ZC_inplace(GEN z)
32 : {
33 14 : long i, l = lg(z);
34 252 : for (i=1; i<l; i++) gel(z,i) = utoi(z[i]);
35 14 : settyp(z, t_COL);
36 14 : return z;
37 : }
38 :
39 : GEN
40 0 : Flm_to_ZM_inplace(GEN z)
41 : {
42 0 : long i, l = lg(z);
43 0 : for (i=1; i<l; i++) Flc_to_ZC_inplace(gel(z, i));
44 0 : return z;
45 : }
46 :
47 : static GEN
48 1822843 : Flm_solve_upper_1(GEN U, GEN B, ulong p, ulong pi)
49 1822843 : { return Flm_Fl_mul_pre(B, Fl_inv(ucoeff(U, 1, 1), p), p, pi); }
50 :
51 : static GEN
52 2822160 : Flm_rsolve_upper_2(GEN U, GEN B, ulong p, ulong pi)
53 : {
54 2822160 : ulong a = ucoeff(U, 1, 1), b = ucoeff(U, 1, 2), d = ucoeff(U, 2, 2);
55 2822160 : ulong D = Fl_mul_pre(a, d, p, pi), Dinv = Fl_inv(D, p);
56 2822356 : ulong ainv = Fl_mul_pre(d, Dinv, p, pi);
57 2822327 : ulong dinv = Fl_mul_pre(a, Dinv, p, pi);
58 2822321 : GEN B1 = rowslice(B, 1, 1);
59 2822124 : GEN B2 = rowslice(B, 2, 2);
60 2822105 : GEN X2 = Flm_Fl_mul_pre(B2, dinv, p, pi);
61 2822290 : GEN X1 = Flm_Fl_mul_pre(Flm_sub(B1, Flm_Fl_mul_pre(X2, b, p, pi), p),
62 : ainv, p, pi);
63 2822290 : return vconcat(X1, X2);
64 : }
65 :
66 : /* solve U*X = B, U upper triangular and invertible */
67 : static GEN
68 6769913 : Flm_rsolve_upper_pre(GEN U, GEN B, ulong p, ulong pi)
69 : {
70 6769913 : long n = lg(U) - 1, n1;
71 : GEN U2, U11, U12, U22, B1, B2, X1, X2, X;
72 6769913 : pari_sp av = avma;
73 :
74 6769913 : if (n == 0) return B;
75 6769906 : if (n == 1) return Flm_solve_upper_1(U, B, p, pi);
76 5660308 : if (n == 2) return Flm_rsolve_upper_2(U, B, p, pi);
77 2838151 : n1 = (n + 1)/2;
78 2838151 : U2 = vecslice(U, n1 + 1, n);
79 2838839 : U22 = rowslice(U2, n1 + 1, n);
80 2838755 : B2 = rowslice(B, n1 + 1, n);
81 2838719 : X2 = Flm_rsolve_upper_pre(U22, B2, p, pi);
82 2838956 : U12 = rowslice(U2, 1, n1);
83 2838751 : B1 = rowslice(B, 1, n1);
84 2838716 : B1 = Flm_sub(B1, Flm_mul_pre(U12, X2, p, pi), p);
85 2838766 : if (gc_needed(av, 1)) (void)gc_all(av, 2, &B1, &X2);
86 2838766 : U11 = matslice(U, 1,n1, 1,n1);
87 2838712 : X1 = Flm_rsolve_upper_pre(U11, B1, p, pi);
88 2838956 : X = vconcat(X1, X2);
89 2838992 : if (gc_needed(av, 1)) X = gc_GEN(av, X);
90 2838991 : return X;
91 : }
92 :
93 : static GEN
94 2565644 : Flm_lsolve_upper_2(GEN U, GEN B, ulong p, ulong pi)
95 : {
96 2565644 : ulong a = ucoeff(U, 1, 1), b = ucoeff(U, 1, 2), d = ucoeff(U, 2, 2);
97 2565644 : ulong D = Fl_mul_pre(a, d, p, pi), Dinv = Fl_inv(D, p);
98 2565680 : ulong ainv = Fl_mul_pre(d, Dinv, p, pi);
99 2565662 : ulong dinv = Fl_mul_pre(a, Dinv, p, pi);
100 2565653 : GEN B1 = vecslice(B, 1, 1);
101 2565645 : GEN B2 = vecslice(B, 2, 2);
102 2565614 : GEN X1 = Flm_Fl_mul_pre(B1, ainv, p, pi);
103 2565658 : GEN X2 = Flm_Fl_mul_pre(Flm_sub(B2, Flm_Fl_mul_pre(X1, b, p, pi), p),
104 : dinv, p, pi);
105 2565654 : return shallowconcat(X1, X2);
106 : }
107 :
108 : /* solve X*U = B, U upper triangular and invertible */
109 : static GEN
110 5533056 : Flm_lsolve_upper_pre(GEN U, GEN B, ulong p, ulong pi)
111 : {
112 5533056 : long n = lg(U) - 1, n1;
113 : GEN U2, U11, U12, U22, B1, B2, X1, X2, X;
114 5533056 : pari_sp av = avma;
115 :
116 5533056 : if (n == 0) return B;
117 5533056 : if (n == 1) return Flm_solve_upper_1(U, B, p, pi);
118 4819785 : if (n == 2) return Flm_lsolve_upper_2(U, B, p, pi);
119 2254143 : n1 = (n + 1)/2;
120 2254143 : U2 = vecslice(U, n1 + 1, n);
121 2254348 : U11 = matslice(U, 1,n1, 1,n1);
122 2254327 : U12 = rowslice(U2, 1, n1);
123 2254316 : U22 = rowslice(U2, n1 + 1, n);
124 2254323 : B1 = vecslice(B, 1, n1);
125 2254310 : B2 = vecslice(B, n1 + 1, n);
126 2254299 : X1 = Flm_lsolve_upper_pre(U11, B1, p, pi);
127 2254335 : B2 = Flm_sub(B2, Flm_mul_pre(X1, U12, p, pi), p);
128 2254339 : if (gc_needed(av, 1)) (void)gc_all(av, 3, &B2, &U22, &X1);
129 2254339 : X2 = Flm_lsolve_upper_pre(U22, B2, p, pi);
130 2254359 : X = shallowconcat(X1, X2);
131 2254355 : if (gc_needed(av, 1)) X = gc_GEN(av, X);
132 2254356 : return X;
133 : }
134 :
135 : static GEN
136 4845424 : Flm_rsolve_lower_unit_2(GEN L, GEN A, ulong p, ulong pi)
137 : {
138 4845424 : GEN X1 = rowslice(A, 1, 1);
139 4845536 : GEN X2 = Flm_sub(rowslice(A, 2, 2),
140 4845370 : Flm_Fl_mul_pre(X1, ucoeff(L, 2, 1), p, pi), p);
141 4845337 : return vconcat(X1, X2);
142 : }
143 :
144 : /* solve L*X = A, L lower triangular with ones on the diagonal
145 : * (at least as many rows as columns) */
146 : static GEN
147 11106737 : Flm_rsolve_lower_unit_pre(GEN L, GEN A, ulong p, ulong pi)
148 : {
149 11106737 : long m = lg(L) - 1, m1, n;
150 : GEN L1, L11, L21, L22, A1, A2, X1, X2, X;
151 11106737 : pari_sp av = avma;
152 :
153 11106737 : if (m == 0) return zero_Flm(0, lg(A) - 1);
154 11106737 : if (m == 1) return rowslice(A, 1, 1);
155 9491663 : if (m == 2) return Flm_rsolve_lower_unit_2(L, A, p, pi);
156 4646245 : m1 = (m + 1)/2;
157 4646245 : n = nbrows(L);
158 4646937 : L1 = vecslice(L, 1, m1);
159 4646959 : L11 = rowslice(L1, 1, m1);
160 4646901 : L21 = rowslice(L1, m1 + 1, n);
161 4646844 : A1 = rowslice(A, 1, m1);
162 4646883 : X1 = Flm_rsolve_lower_unit_pre(L11, A1, p, pi);
163 4647106 : A2 = rowslice(A, m1 + 1, n);
164 4646833 : A2 = Flm_sub(A2, Flm_mul_pre(L21, X1, p, pi), p);
165 4646848 : if (gc_needed(av, 1)) (void)gc_all(av, 2, &A2, &X1);
166 4646848 : L22 = matslice(L, m1+1,n, m1+1,m);
167 4646853 : X2 = Flm_rsolve_lower_unit_pre(L22, A2, p, pi);
168 4646954 : X = vconcat(X1, X2);
169 4647118 : if (gc_needed(av, 1)) X = gc_GEN(av, X);
170 4647120 : return X;
171 : }
172 :
173 : static GEN
174 1954549 : Flm_lsolve_lower_unit_2(GEN L, GEN A, ulong p, ulong pi)
175 : {
176 1954549 : GEN X2 = vecslice(A, 2, 2);
177 1954549 : GEN X1 = Flm_sub(vecslice(A, 1, 1),
178 1954549 : Flm_Fl_mul_pre(X2, ucoeff(L, 2, 1), p, pi), p);
179 1954547 : return shallowconcat(X1, X2);
180 : }
181 :
182 : /* solve L*X = A, L square lower triangular with ones on the diagonal */
183 : static GEN
184 4541600 : Flm_lsolve_lower_unit_pre(GEN L, GEN A, ulong p, ulong pi)
185 : {
186 4541600 : long m = lg(L) - 1, m1;
187 : GEN L1, L2, L11, L21, L22, A1, A2, X1, X2, X;
188 4541600 : pari_sp av = avma;
189 :
190 4541600 : if (m <= 1) return A;
191 4047746 : if (m == 2) return Flm_lsolve_lower_unit_2(L, A, p, pi);
192 2093197 : m1 = (m + 1)/2;
193 2093197 : L2 = vecslice(L, m1 + 1, m);
194 2093214 : L22 = rowslice(L2, m1 + 1, m);
195 2093212 : A2 = vecslice(A, m1 + 1, m);
196 2093210 : X2 = Flm_lsolve_lower_unit_pre(L22, A2, p, pi);
197 2093217 : if (gc_needed(av, 1)) X2 = gc_GEN(av, X2);
198 2093217 : L1 = vecslice(L, 1, m1);
199 2093217 : L21 = rowslice(L1, m1 + 1, m);
200 2093216 : A1 = vecslice(A, 1, m1);
201 2093213 : A1 = Flm_sub(A1, Flm_mul_pre(X2, L21, p, pi), p);
202 2093212 : L11 = rowslice(L1, 1, m1);
203 2093216 : if (gc_needed(av, 1)) (void)gc_all(av, 3, &A1, &L11, &X2);
204 2093216 : X1 = Flm_lsolve_lower_unit_pre(L11, A1, p, pi);
205 2093217 : X = shallowconcat(X1, X2);
206 2093219 : if (gc_needed(av, 1)) X = gc_GEN(av, X);
207 2093219 : return X;
208 : }
209 :
210 : /* destroy A */
211 : static long
212 3620324 : Flm_CUP_basecase(GEN A, GEN *R, GEN *C, GEN *U, GEN *P, ulong p, ulong pi)
213 : {
214 3620324 : long i, j, k, m = nbrows(A), n = lg(A) - 1, pr, pc;
215 : ulong u, v;
216 :
217 3620325 : if (P) *P = identity_perm(n);
218 3620308 : *R = cgetg(m + 1, t_VECSMALL);
219 18058391 : for (j = 1, pr = 0; j <= n; j++)
220 : {
221 20748532 : for (pr++, pc = 0; pr <= m; pr++)
222 : {
223 140284910 : for (k = j; k <= n; k++) { v = ucoeff(A, pr, k); if (!pc && v) pc = k; }
224 19336462 : if (pc) break;
225 : }
226 15850190 : if (!pc) break;
227 14438082 : (*R)[j] = pr;
228 14438082 : if (pc != j)
229 : {
230 2317165 : swap(gel(A, j), gel(A, pc));
231 2317165 : if (P) lswap((*P)[j], (*P)[pc]);
232 : }
233 14438082 : u = Fl_inv(ucoeff(A, pr, j), p);
234 97752669 : for (i = pr + 1; i <= m; i++)
235 : {
236 83314576 : v = Fl_mul_pre(ucoeff(A, i, j), u, p, pi);
237 83313820 : ucoeff(A, i, j) = v;
238 83313820 : v = Fl_neg(v, p);
239 385980319 : for (k = j + 1; k <= n; k++)
240 302663552 : ucoeff(A, i, k) = Fl_addmul_pre(ucoeff(A, i, k),
241 302665937 : ucoeff(A, pr, k), v, p, pi);
242 : }
243 : }
244 3620309 : setlg(*R, j);
245 3620331 : *C = vecslice(A, 1, j - 1);
246 3620314 : if (U) *U = rowpermute(A, *R);
247 3620310 : return j - 1;
248 : }
249 :
250 : static const long Flm_CUP_LIMIT = 8;
251 :
252 : static long
253 3510039 : Flm_CUP_pre(GEN A, GEN *R, GEN *C, GEN *U, GEN *P, ulong p, ulong pi)
254 : {
255 3510039 : long m = nbrows(A), m1, n = lg(A) - 1, i, r1, r2, r;
256 : GEN R1, C1, U1, P1, R2, C2, U2, P2;
257 : GEN A1, A2, B2, C21, U11, U12, T21, T22;
258 3510032 : pari_sp av = avma;
259 :
260 3510032 : if (m < Flm_CUP_LIMIT || n < Flm_CUP_LIMIT)
261 : /* destroy A; not called at the outermost recursion level */
262 2458730 : return Flm_CUP_basecase(A, R, C, U, P, p, pi);
263 1051302 : m1 = (minss(m, n) + 1)/2;
264 1051302 : A1 = rowslice(A, 1, m1);
265 1051288 : A2 = rowslice(A, m1 + 1, m);
266 1051300 : r1 = Flm_CUP_pre(A1, &R1, &C1, &U1, &P1, p, pi);
267 1051306 : if (r1 == 0)
268 : {
269 26732 : r2 = Flm_CUP_pre(A2, &R2, &C2, &U2, &P2, p, pi);
270 26732 : *R = cgetg(r2 + 1, t_VECSMALL);
271 36886 : for (i = 1; i <= r2; i++) (*R)[i] = R2[i] + m1;
272 26732 : *C = vconcat(zero_Flm(m1, r2), C2);
273 26732 : *U = U2;
274 26732 : *P = P2;
275 26732 : r = r2;
276 : }
277 : else
278 : {
279 1024574 : U11 = vecslice(U1, 1, r1);
280 1024570 : U12 = vecslice(U1, r1 + 1, n);
281 1024568 : T21 = vecslicepermute(A2, P1, 1, r1);
282 1024567 : T22 = vecslicepermute(A2, P1, r1 + 1, n);
283 1024567 : C21 = Flm_lsolve_upper_pre(U11, T21, p, pi);
284 1024571 : if (gc_needed(av, 1))
285 0 : (void)gc_all(av, 7, &R1, &C1, &P1, &U11, &U12, &T22, &C21);
286 1024571 : B2 = Flm_sub(T22, Flm_mul_pre(C21, U12, p, pi), p);
287 1024572 : r2 = Flm_CUP_pre(B2, &R2, &C2, &U2, &P2, p, pi);
288 1024574 : r = r1 + r2;
289 1024574 : *R = cgetg(r + 1, t_VECSMALL);
290 6869216 : for (i = 1; i <= r1; i++) (*R)[i] = R1[i];
291 6393511 : for (; i <= r; i++) (*R)[i] = R2[i - r1] + m1;
292 1024569 : *C = shallowconcat(vconcat(C1, C21),
293 : vconcat(zero_Flm(m1, r2), C2));
294 1024573 : *U = shallowconcat(vconcat(U11, zero_Flm(r2, r1)),
295 : vconcat(vecpermute(U12, P2), U2));
296 1024576 : *P = cgetg(n + 1, t_VECSMALL);
297 6869235 : for (i = 1; i <= r1; i++) (*P)[i] = P1[i];
298 12771673 : for (; i <= n; i++) (*P)[i] = P1[P2[i - r1] + r1];
299 : }
300 1051304 : if (gc_needed(av, 1)) (void)gc_all(av, 4, R, C, U, P);
301 1051305 : return r;
302 : }
303 :
304 : static long
305 1161574 : Flm_echelon_gauss(GEN A, GEN *R, GEN *C, ulong p, ulong pi)
306 1161574 : { return Flm_CUP_basecase(A, R, C, NULL, NULL, p, pi); }
307 :
308 : /* complement of a strictly increasing subsequence of (1, 2, ..., n) */
309 : static GEN
310 1076039 : indexcompl(GEN v, long n)
311 : {
312 1076039 : long i, j, k, m = lg(v) - 1;
313 1076039 : GEN w = cgetg(n - m + 1, t_VECSMALL);
314 23225880 : for (i = j = k = 1; i <= n; i++)
315 22149842 : if (j <= m && v[j] == i) j++; else w[k++] = i;
316 1076038 : return w;
317 : }
318 :
319 : /* column echelon form */
320 : static long
321 1966353 : Flm_echelon_pre(GEN A, GEN *R, GEN *C, ulong p, ulong pi)
322 : {
323 1966353 : long j, j1, j2, m = nbrows(A), n = lg(A) - 1, n1, r, r1, r2;
324 : GEN A1, A2, R1, R1c, C1, R2, C2;
325 : GEN A12, A22, B2, C11, C21, M12;
326 1966352 : pari_sp av = avma;
327 :
328 1966352 : if (m < Flm_CUP_LIMIT || n < Flm_CUP_LIMIT)
329 1161572 : return Flm_echelon_gauss(Flm_copy(A), R, C, p, pi);
330 :
331 804780 : n1 = (n + 1)/2;
332 804780 : A1 = vecslice(A, 1, n1);
333 804780 : A2 = vecslice(A, n1 + 1, n);
334 804780 : r1 = Flm_echelon_pre(A1, &R1, &C1, p, pi);
335 804778 : if (!r1) return Flm_echelon_pre(A2, R, C, p, pi);
336 728653 : if (r1 == m) { *R = R1; *C = C1; return r1; }
337 :
338 720580 : R1c = indexcompl(R1, m);
339 720581 : C11 = rowpermute(C1, R1);
340 720581 : C21 = rowpermute(C1, R1c);
341 720581 : A12 = rowpermute(A2, R1);
342 720581 : A22 = rowpermute(A2, R1c);
343 720582 : M12 = Flm_rsolve_lower_unit_pre(C11, A12, p, pi);
344 720582 : B2 = Flm_sub(A22, Flm_mul_pre(C21, M12, p, pi), p);
345 720581 : r2 = Flm_echelon_pre(B2, &R2, &C2, p, pi);
346 720581 : if (!r2) { *R = R1; *C = C1; r = r1; }
347 : else
348 : {
349 673901 : R2 = perm_mul(R1c, R2);
350 673901 : C2 = rowpermute(vconcat(zero_Flm(r1, r2), C2),
351 : perm_inv(vecsmall_concat(R1, R1c)));
352 673901 : r = r1 + r2;
353 673901 : *R = cgetg(r + 1, t_VECSMALL);
354 673901 : *C = cgetg(r + 1, t_MAT);
355 8434024 : for (j = j1 = j2 = 1; j <= r; j++)
356 7760123 : if (j2 > r2 || (j1 <= r1 && R1[j1] < R2[j2]))
357 : {
358 4112627 : gel(*C, j) = gel(C1, j1);
359 4112627 : (*R)[j] = R1[j1++];
360 : }
361 : else
362 : {
363 3647496 : gel(*C, j) = gel(C2, j2);
364 3647496 : (*R)[j] = R2[j2++];
365 : }
366 : }
367 720581 : if (gc_needed(av, 1)) (void)gc_all(av, 2, R, C);
368 720581 : return r;
369 : }
370 :
371 : static void /* assume m < p */
372 12338193 : _Fl_addmul(GEN b, long k, long i, ulong m, ulong p, ulong pi)
373 : {
374 12338193 : uel(b,k) = Fl_addmul_pre(uel(b, k), m, uel(b, i), p, pi);
375 12338207 : }
376 : static void /* same m = 1 */
377 655799 : _Fl_add(GEN b, long k, long i, ulong p)
378 : {
379 655799 : uel(b,k) = Fl_add(uel(b,k), uel(b,i), p);
380 655799 : }
381 : static void /* assume m < p && SMALL_ULONG(p) && (! (b[i] & b[k] & HIGHMASK)) */
382 4421969 : _Fl_addmul_OK(GEN b, long k, long i, ulong m, ulong p)
383 : {
384 4421969 : uel(b,k) += m * uel(b,i);
385 4421969 : if (uel(b,k) & HIGHMASK) uel(b,k) %= p;
386 4421969 : }
387 : static void /* assume SMALL_ULONG(p) && (! (b[i] & b[k] & HIGHMASK)) */
388 2200244 : _Fl_add_OK(GEN b, long k, long i, ulong p)
389 : {
390 2200244 : uel(b,k) += uel(b,i);
391 2200244 : if (uel(b,k) & HIGHMASK) uel(b,k) %= p;
392 2200244 : }
393 :
394 : /* assume 0 <= a[i,j] < p */
395 : static GEN
396 451009 : Fl_get_col_OK(GEN a, GEN b, long li, ulong p)
397 : {
398 451009 : GEN u = cgetg(li+1,t_VECSMALL);
399 451006 : ulong m = uel(b,li) % p;
400 : long i,j;
401 :
402 451006 : uel(u,li) = (m * ucoeff(a,li,li)) % p;
403 1743449 : for (i = li-1; i > 0; i--)
404 : {
405 1292443 : m = p - uel(b,i)%p;
406 4146489 : for (j = i+1; j <= li; j++) {
407 2854046 : if (m & HIGHBIT) m %= p;
408 2854046 : m += ucoeff(a,i,j) * uel(u,j); /* 0 <= u[j] < p */
409 : }
410 1292443 : m %= p;
411 1292443 : if (m) m = ((p-m) * ucoeff(a,i,i)) % p;
412 1292443 : uel(u,i) = m;
413 : }
414 451006 : return u;
415 : }
416 : static GEN
417 2347208 : Fl_get_col(GEN a, GEN b, long li, ulong p)
418 : {
419 2347208 : GEN u = cgetg(li+1,t_VECSMALL);
420 2347204 : ulong m = uel(b,li) % p;
421 : long i,j;
422 :
423 2347204 : uel(u,li) = Fl_mul(m, ucoeff(a,li,li), p);
424 6116775 : for (i=li-1; i>0; i--)
425 : {
426 3769566 : m = b[i]%p;
427 9557190 : for (j = i+1; j <= li; j++)
428 5787631 : m = Fl_sub(m, Fl_mul(ucoeff(a,i,j), uel(u,j), p), p);
429 3769559 : if (m) m = Fl_mul(m, ucoeff(a,i,i), p);
430 3769562 : uel(u,i) = m;
431 : }
432 2347209 : return u;
433 : }
434 :
435 : static GEN
436 671265 : Flm_ker_gauss_OK(GEN x, ulong p, long deplin)
437 : {
438 : GEN y, c, d;
439 : long i, j, k, r, t, m, n;
440 : ulong a;
441 :
442 671265 : n = lg(x)-1;
443 671265 : m=nbrows(x); r=0;
444 :
445 671264 : c = zero_zv(m);
446 671263 : d = cgetg(n+1, t_VECSMALL);
447 671259 : a = 0; /* for gcc -Wall */
448 3294917 : for (k=1; k<=n; k++)
449 : {
450 9512011 : for (j=1; j<=m; j++)
451 8315712 : if (!c[j])
452 : {
453 4475989 : a = ucoeff(x,j,k) % p;
454 4475989 : if (a) break;
455 : }
456 2677819 : if (j > m)
457 : {
458 1196311 : if (deplin==1) {
459 54169 : c = cgetg(n+1, t_VECSMALL);
460 177220 : for (i=1; i<k; i++) c[i] = ucoeff(x,d[i],k) % p;
461 105661 : c[k] = 1; for (i=k+1; i<=n; i++) c[i] = 0;
462 54169 : return c;
463 : }
464 1142142 : r++; d[k] = 0;
465 : }
466 : else
467 : {
468 1481508 : ulong piv = p - Fl_inv(a, p); /* -1/a */
469 1481518 : c[j] = k; d[k] = j;
470 1481518 : ucoeff(x,j,k) = p-1;
471 1481518 : if (piv != 1)
472 3189158 : for (i=k+1; i<=n; i++) ucoeff(x,j,i) = (piv * ucoeff(x,j,i)) % p;
473 7572350 : for (t=1; t<=m; t++)
474 : {
475 6090834 : if (t == j) continue;
476 :
477 4609314 : piv = ( ucoeff(x,t,k) %= p );
478 4609314 : if (!piv) continue;
479 2164846 : if (piv == 1)
480 2545783 : for (i=k+1; i<=n; i++) _Fl_add_OK(gel(x,i),t,j, p);
481 : else
482 4860386 : for (i=k+1; i<=n; i++) _Fl_addmul_OK(gel(x,i),t,j,piv, p);
483 : }
484 : }
485 : }
486 617098 : if (deplin==1) return NULL;
487 :
488 617091 : y = cgetg(r+1, t_MAT);
489 1759233 : for (j=k=1; j<=r; j++,k++)
490 : {
491 1142143 : GEN C = cgetg(n+1, t_VECSMALL);
492 :
493 2213334 : gel(y,j) = C; while (d[k]) k++;
494 9379732 : for (i=1; i<k; i++)
495 8237590 : if (d[i])
496 2342516 : uel(C,i) = ucoeff(x,d[i],k) % p;
497 : else
498 5895074 : uel(C,i) = 0UL;
499 7764372 : uel(C,k) = 1UL; for (i=k+1; i<=n; i++) uel(C,i) = 0UL;
500 : }
501 617090 : if (deplin == 2) {
502 0 : GEN pc = cgetg(n - r + 1, t_VECSMALL); /* indices of pivot columns */
503 0 : for (i = j = 1; j <= n; j++)
504 0 : if (d[j]) pc[i++] = j;
505 0 : return mkvec2(y, pc);
506 : }
507 617090 : return y;
508 : }
509 :
510 : /* in place, destroy x */
511 : static GEN
512 818707 : Flm_ker_gauss(GEN x, ulong p, long deplin)
513 : {
514 : GEN y, c, d;
515 : long i, j, k, r, t, m, n;
516 : ulong a, pi;
517 818707 : n = lg(x)-1;
518 818707 : if (!n) return cgetg(1,t_MAT);
519 818700 : if (SMALL_ULONG(p)) return Flm_ker_gauss_OK(x, p, deplin);
520 147435 : pi = get_Fl_red(p);
521 :
522 147435 : m=nbrows(x); r=0;
523 :
524 147435 : c = zero_zv(m);
525 147435 : d = cgetg(n+1, t_VECSMALL);
526 147434 : a = 0; /* for gcc -Wall */
527 475209 : for (k=1; k<=n; k++)
528 : {
529 857784 : for (j=1; j<=m; j++)
530 754231 : if (!c[j])
531 : {
532 569532 : a = ucoeff(x,j,k);
533 569532 : if (a) break;
534 : }
535 327781 : if (j > m)
536 : {
537 103554 : if (deplin==1) {
538 7 : c = cgetg(n+1, t_VECSMALL);
539 21 : for (i=1; i<k; i++) c[i] = ucoeff(x,d[i],k);
540 7 : c[k] = 1; for (i=k+1; i<=n; i++) c[i] = 0;
541 7 : return c;
542 : }
543 103547 : r++; d[k] = 0;
544 : }
545 : else
546 : {
547 224227 : ulong piv = p - Fl_inv(a, p); /* -1/a */
548 224228 : c[j] = k; d[k] = j;
549 224228 : ucoeff(x,j,k) = p-1;
550 224228 : if (piv != 1)
551 406345 : for (i=k+1; i<=n; i++)
552 188040 : ucoeff(x,j,i) = Fl_mul_pre(piv, ucoeff(x,j,i), p, pi);
553 977451 : for (t=1; t<=m; t++)
554 : {
555 753223 : if (t == j) continue;
556 :
557 528995 : piv = ucoeff(x,t,k);
558 528995 : if (!piv) continue;
559 310998 : if (piv == 1)
560 46488 : for (i=k+1; i<=n; i++) _Fl_add(gel(x,i),t,j,p);
561 : else
562 720011 : for (i=k+1; i<=n; i++) _Fl_addmul(gel(x,i),t,j,piv,p, pi);
563 : }
564 : }
565 : }
566 147428 : if (deplin==1) return NULL;
567 :
568 147421 : y = cgetg(r+1, t_MAT);
569 250968 : for (j=k=1; j<=r; j++,k++)
570 : {
571 103547 : GEN C = cgetg(n+1, t_VECSMALL);
572 :
573 166678 : gel(y,j) = C; while (d[k]) k++;
574 218797 : for (i=1; i<k; i++)
575 115250 : if (d[i])
576 79412 : uel(C,i) = ucoeff(x,d[i],k);
577 : else
578 35838 : uel(C,i) = 0UL;
579 167411 : uel(C,k) = 1UL; for (i=k+1; i<=n; i++) uel(C,i) = 0UL;
580 : }
581 147421 : if (deplin == 2) {
582 142563 : GEN pc = cgetg(n - r + 1, t_VECSMALL); /* indices of pivot columns */
583 443130 : for (i = j = 1; j <= n; j++)
584 300567 : if (d[j]) pc[i++] = j;
585 142563 : return mkvec2(y, pc);
586 : }
587 4858 : return y;
588 : }
589 :
590 : GEN
591 272452 : Flm_intersect_i(GEN x, GEN y, ulong p)
592 : {
593 272452 : long j, lx = lg(x);
594 : GEN z;
595 :
596 272452 : if (lx==1 || lg(y)==1) return cgetg(1,t_MAT);
597 272438 : z = Flm_ker(shallowconcat(x,y), p);
598 1476648 : for (j=lg(z)-1; j; j--) setlg(gel(z,j),lx);
599 272438 : return Flm_mul(x,z,p);
600 : }
601 : GEN
602 0 : Flm_intersect(GEN x, GEN y, ulong p)
603 : {
604 0 : pari_sp av = avma;
605 0 : return gc_upto(av, Flm_image(Flm_intersect_i(x, y, p), p));
606 : }
607 :
608 : static GEN
609 324428 : Flm_ker_echelon(GEN x, ulong p, long pivots) {
610 324428 : pari_sp av = avma;
611 : GEN R, Rc, C, C1, C2, S, K;
612 324428 : long n = lg(x) - 1, r;
613 324428 : ulong pi = get_Fl_red(p);
614 324428 : r = Flm_echelon_pre(Flm_transpose(x), &R, &C, p, pi);
615 324428 : Rc = indexcompl(R, n);
616 324428 : C1 = rowpermute(C, R);
617 324428 : C2 = rowpermute(C, Rc);
618 324428 : S = Flm_lsolve_lower_unit_pre(C1, C2, p, pi);
619 324428 : K = vecpermute(shallowconcat(Flm_neg(S, p), matid_Flm(n - r)),
620 : perm_inv(vecsmall_concat(R, Rc)));
621 324428 : K = Flm_transpose(K);
622 324428 : if (pivots)
623 33940 : return gc_GEN(av, mkvec2(K, R));
624 290488 : return gc_upto(av, K);
625 : }
626 :
627 : static GEN
628 30752 : Flm_deplin_echelon(GEN x, ulong p) {
629 30752 : pari_sp av = avma;
630 : GEN R, Rc, C, C1, C2, s, v;
631 30752 : long i, n = lg(x) - 1, r;
632 30752 : ulong pi = get_Fl_red(p);
633 30752 : r = Flm_echelon_pre(Flm_transpose(x), &R, &C, p, pi);
634 30752 : if (r == n) return gc_NULL(av);
635 30745 : Rc = indexcompl(R, n);
636 30745 : i = Rc[1];
637 30745 : C1 = rowpermute(C, R);
638 30745 : C2 = rowslice(C, i, i);
639 30745 : s = Flm_row(Flm_lsolve_lower_unit_pre(C1, C2, p, pi), 1);
640 30745 : v = vecsmallpermute(vecsmall_concat(Flv_neg(s, p), vecsmall_ei(n - r, 1)),
641 : perm_inv(vecsmall_concat(R, Rc)));
642 30745 : return gc_uptoleaf(av, v);
643 : }
644 :
645 : static GEN
646 1173885 : Flm_ker_i(GEN x, ulong p, long deplin, long inplace) {
647 1173885 : if (lg(x) - 1 >= Flm_CUP_LIMIT && nbrows(x) >= Flm_CUP_LIMIT)
648 355180 : switch(deplin) {
649 290488 : case 0: return Flm_ker_echelon(x, p, 0);
650 30752 : case 1: return Flm_deplin_echelon(x, p);
651 33940 : case 2: return Flm_ker_echelon(x, p, 1);
652 : }
653 818705 : return Flm_ker_gauss(inplace? x: Flm_copy(x), p, deplin);
654 : }
655 :
656 : GEN
657 620688 : Flm_ker_sp(GEN x, ulong p, long deplin) { return Flm_ker_i(x, p, deplin, 1); }
658 : GEN
659 553201 : Flm_ker(GEN x, ulong p) { return Flm_ker_i(x, p, 0, 0); }
660 : GEN
661 0 : Flm_deplin(GEN x, ulong p) { return Flm_ker_i(x, p, 1, 0); }
662 :
663 : /* in place, destroy a, SMALL_ULONG(p) is TRUE */
664 : static ulong
665 2317 : Flm_det_gauss_OK(GEN a, long nbco, ulong p)
666 : {
667 2317 : long i,j,k, s = 1;
668 2317 : ulong q, x = 1;
669 :
670 9562 : for (i=1; i<nbco; i++)
671 : {
672 8904 : for(k=i; k<=nbco; k++)
673 : {
674 8715 : ulong c = ucoeff(a,k,i) % p;
675 8715 : ucoeff(a,k,i) = c;
676 8715 : if (c) break;
677 : }
678 23289 : for(j=k+1; j<=nbco; j++) ucoeff(a,j,i) %= p;
679 7434 : if (k > nbco) return ucoeff(a,i,i);
680 7245 : if (k != i)
681 : { /* exchange the lines s.t. k = i */
682 3192 : for (j=i; j<=nbco; j++) lswap(ucoeff(a,i,j), ucoeff(a,k,j));
683 791 : s = -s;
684 : }
685 7245 : q = ucoeff(a,i,i);
686 :
687 7245 : if (x & HIGHMASK) x %= p;
688 7245 : x *= q;
689 7245 : q = Fl_inv(q,p);
690 24185 : for (k=i+1; k<=nbco; k++)
691 : {
692 16940 : ulong m = ucoeff(a,i,k) % p;
693 16940 : if (!m) continue;
694 :
695 9898 : m = p - ((m*q)%p);
696 39165 : for (j=i+1; j<=nbco; j++)
697 : {
698 29267 : ulong c = ucoeff(a,j,k);
699 29267 : if (c & HIGHMASK) c %= p;
700 29267 : ucoeff(a,j,k) = c + m*ucoeff(a,j,i);
701 : }
702 : }
703 : }
704 2128 : if (x & HIGHMASK) x %= p;
705 2128 : q = ucoeff(a,nbco,nbco);
706 2128 : if (q & HIGHMASK) q %= p;
707 2128 : x = (x*q) % p;
708 2128 : if (s < 0 && x) x = p - x;
709 2128 : return x;
710 : }
711 :
712 : /* in place, destroy a */
713 : static ulong
714 53344 : Flm_det_gauss(GEN a, ulong p)
715 : {
716 53344 : long i,j,k, s = 1, nbco = lg(a)-1;
717 53344 : ulong pi, q, x = 1;
718 :
719 53344 : if (SMALL_ULONG(p)) return Flm_det_gauss_OK(a, nbco, p);
720 51027 : pi = get_Fl_red(p);
721 325511 : for (i=1; i<nbco; i++)
722 : {
723 274885 : for(k=i; k<=nbco; k++)
724 274885 : if (ucoeff(a,k,i)) break;
725 274482 : if (k > nbco) return ucoeff(a,i,i);
726 274482 : if (k != i)
727 : { /* exchange the lines s.t. k = i */
728 1090 : for (j=i; j<=nbco; j++) lswap(ucoeff(a,i,j), ucoeff(a,k,j));
729 212 : s = -s;
730 : }
731 274482 : q = ucoeff(a,i,i);
732 :
733 274482 : x = Fl_mul_pre(x, q, p, pi);
734 274482 : q = Fl_inv(q,p);
735 1176166 : for (k=i+1; k<=nbco; k++)
736 : {
737 901682 : ulong m = ucoeff(a,i,k);
738 901682 : if (!m) continue;
739 :
740 842421 : m = Fl_mul_pre(m, q, p, pi);
741 4329470 : for (j=i+1; j<=nbco; j++)
742 3487053 : ucoeff(a,j,k) = Fl_sub(ucoeff(a,j,k), Fl_mul_pre(m,ucoeff(a,j,i), p, pi), p);
743 : }
744 : }
745 51029 : if (s < 0) x = Fl_neg(x, p);
746 51029 : return Fl_mul(x, ucoeff(a,nbco,nbco), p);
747 : }
748 :
749 : static ulong
750 37400 : Flm_det_CUP(GEN a, ulong p) {
751 : GEN R, C, U, P;
752 37400 : long i, n = lg(a) - 1, r;
753 : ulong d;
754 37400 : ulong pi = get_Fl_red(p);
755 37400 : r = Flm_CUP_pre(a, &R, &C, &U, &P, p, pi);
756 37400 : if (r < n)
757 42 : d = 0;
758 : else {
759 37358 : d = perm_sign(P) == 1? 1: p-1;
760 429958 : for (i = 1; i <= n; i++)
761 392600 : d = Fl_mul_pre(d, ucoeff(U, i, i), p, pi);
762 : }
763 37400 : return d;
764 : }
765 :
766 : static ulong
767 90744 : Flm_det_i(GEN x, ulong p, long inplace) {
768 90744 : pari_sp av = avma;
769 : ulong d;
770 90744 : if (lg(x) - 1 >= Flm_CUP_LIMIT)
771 37400 : d = Flm_det_CUP(x, p);
772 : else
773 53344 : d = Flm_det_gauss(inplace? x: Flm_copy(x), p);
774 90744 : return gc_ulong(av, d);
775 : }
776 :
777 : ulong
778 90744 : Flm_det_sp(GEN x, ulong p) { return Flm_det_i(x, p, 1); }
779 : ulong
780 0 : Flm_det(GEN x, ulong p) { return Flm_det_i(x, p, 0); }
781 :
782 : /* Destroy x */
783 : static GEN
784 4371266 : Flm_gauss_pivot(GEN x, ulong p, long *rr)
785 : {
786 : GEN c,d;
787 : long i,j,k,r,t,n,m;
788 :
789 4371266 : n=lg(x)-1; if (!n) { *rr=0; return NULL; }
790 :
791 4369957 : m=nbrows(x); r=0;
792 4369957 : d=cgetg(n+1,t_VECSMALL);
793 4369948 : c = zero_zv(m);
794 18825264 : for (k=1; k<=n; k++)
795 : {
796 36062974 : for (j=1; j<=m; j++)
797 34256576 : if (!c[j])
798 : {
799 18387234 : ucoeff(x,j,k) %= p;
800 18387234 : if (ucoeff(x,j,k)) break;
801 : }
802 14455292 : if (j>m) { r++; d[k]=0; }
803 : else
804 : {
805 12648852 : ulong piv = p - Fl_inv(ucoeff(x,j,k), p);
806 12648936 : c[j]=k; d[k]=j;
807 29127372 : for (i=k+1; i<=n; i++)
808 16478440 : ucoeff(x,j,i) = Fl_mul(piv, ucoeff(x,j,i), p);
809 60295137 : for (t=1; t<=m; t++)
810 47646350 : if (!c[t]) /* no pivot on that line yet */
811 : {
812 20452468 : piv = ucoeff(x,t,k);
813 20452468 : if (piv)
814 : {
815 12028336 : ucoeff(x,t,k) = 0;
816 37301598 : for (i=k+1; i<=n; i++)
817 25273387 : ucoeff(x,t,i) = Fl_add(ucoeff(x,t,i),
818 25273407 : Fl_mul(piv,ucoeff(x,j,i),p),p);
819 : }
820 : }
821 41776019 : for (i=k; i<=n; i++) ucoeff(x,j,i) = 0; /* dummy */
822 : }
823 : }
824 4369972 : *rr = r; return gc_const((pari_sp)d, d);
825 : }
826 :
827 : static GEN
828 277006 : Flm_pivots_CUP(GEN x, ulong p, long *rr)
829 : {
830 277006 : long i, n = lg(x) - 1, r;
831 277006 : GEN R, C, U, P, d = zero_zv(n);
832 277006 : ulong pi = get_Fl_red(p);
833 277006 : r = Flm_CUP_pre(x, &R, &C, &U, &P, p, pi);
834 3045991 : for(i = 1; i <= r; i++)
835 2768985 : d[P[i]] = R[i];
836 277006 : *rr = n - r; return gc_const((pari_sp)d, d);
837 : }
838 :
839 : GEN
840 4648268 : Flm_pivots(GEN x, ulong p, long *rr, long inplace)
841 : {
842 4648268 : if (lg(x) - 1 >= Flm_CUP_LIMIT && nbrows(x) >= Flm_CUP_LIMIT)
843 277005 : return Flm_pivots_CUP(x, p, rr);
844 4371263 : return Flm_gauss_pivot(inplace? x: Flm_copy(x), p, rr);
845 : }
846 :
847 : long
848 39802 : Flm_rank(GEN x, ulong p)
849 : {
850 39802 : pari_sp av = avma;
851 : long r;
852 39802 : if (lg(x) - 1 >= Flm_CUP_LIMIT && nbrows(x) >= Flm_CUP_LIMIT) {
853 : GEN R, C;
854 9688 : ulong pi = get_Fl_red(p);
855 9688 : return gc_long(av, Flm_echelon_pre(x, &R, &C, p, pi));
856 : }
857 30114 : (void) Flm_pivots(x, p, &r, 0);
858 30114 : return gc_long(av, lg(x)-1 - r);
859 : }
860 :
861 : /* assume dim A >= 1, A invertible + upper triangular, 1s on diagonal,
862 : * reduced mod p */
863 : static GEN
864 1274 : Flm_inv_upper_1_ind(GEN A, long index, ulong p)
865 : {
866 1274 : long n = lg(A)-1, i = index, j;
867 1274 : GEN u = const_vecsmall(n, 0);
868 1274 : u[i] = 1;
869 1274 : if (SMALL_ULONG(p))
870 3269 : for (i--; i>0; i--)
871 : {
872 2009 : ulong m = ucoeff(A,i,i+1) * uel(u,i+1); /* j = i+1 */
873 7035 : for (j=i+2; j<=n; j++)
874 : {
875 5026 : if (m & HIGHMASK) m %= p;
876 5026 : m += ucoeff(A,i,j) * uel(u,j);
877 : }
878 2009 : u[i] = Fl_neg(m % p, p);
879 : }
880 : else
881 21 : for (i--; i>0; i--)
882 : {
883 7 : ulong m = Fl_mul(ucoeff(A,i,i+1),uel(u,i+1), p); /* j = i+1 */
884 7 : for (j=i+2; j<=n; j++) m = Fl_add(m, Fl_mul(ucoeff(A,i,j),uel(u,j),p), p);
885 7 : u[i] = Fl_neg(m, p);
886 : }
887 1274 : return u;
888 : }
889 : static GEN
890 490 : Flm_inv_upper_1(GEN A, ulong p)
891 : {
892 : long i, l;
893 490 : GEN B = cgetg_copy(A, &l);
894 1764 : for (i = 1; i < l; i++) gel(B,i) = Flm_inv_upper_1_ind(A, i, p);
895 490 : return B;
896 : }
897 : /* destroy a, b */
898 : static GEN
899 121397 : Flm_gauss_sp_OK(GEN a, GEN b, ulong *detp, ulong p)
900 : {
901 121397 : long i, j, k, li, bco, aco = lg(a)-1, s = 1;
902 121397 : ulong det = 1;
903 : GEN u;
904 :
905 121397 : li = nbrows(a);
906 121397 : bco = lg(b)-1;
907 427285 : for (i=1; i<=aco; i++)
908 : {
909 : ulong invpiv;
910 : /* Fl_get_col wants 0 <= a[i,j] < p for all i,j */
911 1054632 : for (k = 1; k < i; k++) ucoeff(a,k,i) %= p;
912 484784 : for (k = i; k <= li; k++)
913 : {
914 484777 : ulong piv = ( ucoeff(a,k,i) %= p );
915 484777 : if (piv)
916 : {
917 427278 : ucoeff(a,k,i) = Fl_inv(piv, p);
918 427278 : if (detp)
919 : {
920 0 : if (det & HIGHMASK) det %= p;
921 0 : det *= piv;
922 : }
923 427278 : break;
924 : }
925 : }
926 : /* found a pivot on line k */
927 427285 : if (k > li) return NULL;
928 427278 : if (k != i)
929 : { /* swap lines so that k = i */
930 38484 : s = -s;
931 159256 : for (j=i; j<=aco; j++) swap(gcoeff(a,i,j), gcoeff(a,k,j));
932 208681 : for (j=1; j<=bco; j++) swap(gcoeff(b,i,j), gcoeff(b,k,j));
933 : }
934 427278 : if (i == aco) break;
935 :
936 305888 : invpiv = p - ucoeff(a,i,i); /* -1/piv mod p */
937 971044 : for (k=i+1; k<=li; k++)
938 : {
939 665156 : ulong m = ( ucoeff(a,k,i) %= p );
940 665156 : if (!m) continue;
941 :
942 186965 : m = Fl_mul(m, invpiv, p);
943 186965 : if (m == 1) {
944 145286 : for (j=i+1; j<=aco; j++) _Fl_add_OK(gel(a,j),k,i, p);
945 230304 : for (j=1; j<=bco; j++) _Fl_add_OK(gel(b,j),k,i, p);
946 : } else {
947 520400 : for (j=i+1; j<=aco; j++) _Fl_addmul_OK(gel(a,j),k,i,m, p);
948 858844 : for (j=1; j<=bco; j++) _Fl_addmul_OK(gel(b,j),k,i,m, p);
949 : }
950 : }
951 : }
952 121390 : if (detp)
953 : {
954 0 : det %= p;
955 0 : if (s < 0 && det) det = p - det;
956 0 : *detp = det;
957 : }
958 121390 : u = cgetg(bco+1,t_MAT);
959 572397 : for (j=1; j<=bco; j++) gel(u,j) = Fl_get_col_OK(a,gel(b,j), aco,p);
960 121388 : return u;
961 : }
962 :
963 : /* destroy a, b */
964 : static GEN
965 2343835 : Flm_gauss_sp_i(GEN a, GEN b, ulong *detp, ulong p)
966 : {
967 2343835 : long i, j, k, li, bco, aco = lg(a)-1, s = 1;
968 2343835 : ulong det = 1;
969 : GEN u;
970 : ulong pi;
971 2343835 : if (!aco) { if (detp) *detp = 1; return cgetg(1,t_MAT); }
972 2343835 : if (SMALL_ULONG(p)) return Flm_gauss_sp_OK(a, b, detp, p);
973 2222438 : pi = get_Fl_red(p);
974 2222438 : li = nbrows(a);
975 2222438 : bco = lg(b)-1;
976 5698290 : for (i=1; i<=aco; i++)
977 : {
978 : ulong invpiv;
979 : /* Fl_get_col wants 0 <= a[i,j] < p for all i,j */
980 5929739 : for (k = i; k <= li; k++)
981 : {
982 5929739 : ulong piv = ucoeff(a,k,i);
983 5929739 : if (piv)
984 : {
985 5698292 : ucoeff(a,k,i) = Fl_inv(piv, p);
986 5698287 : if (detp) det = Fl_mul_pre(det, piv, p, pi);
987 5698287 : break;
988 : }
989 : }
990 : /* found a pivot on line k */
991 5698287 : if (k > li) return NULL;
992 5698287 : if (k != i)
993 : { /* swap lines so that k = i */
994 174979 : s = -s;
995 654705 : for (j=i; j<=aco; j++) swap(gcoeff(a,i,j), gcoeff(a,k,j));
996 355687 : for (j=1; j<=bco; j++) swap(gcoeff(b,i,j), gcoeff(b,k,j));
997 : }
998 5698287 : if (i == aco) break;
999 :
1000 3475845 : invpiv = p - ucoeff(a,i,i); /* -1/piv mod p */
1001 8687403 : for (k=i+1; k<=li; k++)
1002 : {
1003 5211551 : ulong m = ucoeff(a,k,i);
1004 5211551 : if (!m) continue;
1005 :
1006 4351598 : m = Fl_mul_pre(m, invpiv, p, pi);
1007 4351597 : if (m == 1) {
1008 626254 : for (j=i+1; j<=aco; j++) _Fl_add(gel(a,j),k,i, p);
1009 434229 : for (j=1; j<=bco; j++) _Fl_add(gel(b,j),k,i, p);
1010 : } else {
1011 11855278 : for (j=i+1; j<=aco; j++) _Fl_addmul(gel(a,j),k,i,m, p, pi);
1012 8325946 : for (j=1; j<=bco; j++) _Fl_addmul(gel(b,j),k,i,m, p, pi);
1013 : }
1014 : }
1015 : }
1016 2222440 : if (detp)
1017 : {
1018 0 : if (s < 0 && det) det = p - det;
1019 0 : *detp = det;
1020 : }
1021 2222440 : u = cgetg(bco+1,t_MAT);
1022 4569647 : for (j=1; j<=bco; j++) gel(u,j) = Fl_get_col(a,gel(b,j), aco,p);
1023 2222441 : return u;
1024 : }
1025 :
1026 : static GEN
1027 1092717 : Flm_gauss_from_CUP(GEN b, GEN R, GEN C, GEN U, GEN P, ulong p, ulong pi, ulong *detp)
1028 : {
1029 1092717 : GEN Y = Flm_rsolve_lower_unit_pre(rowpermute(C, R), rowpermute(b, R), p, pi);
1030 1092735 : GEN X = rowpermute(Flm_rsolve_upper_pre(U, Y, p, pi), perm_inv(P));
1031 1092739 : if (detp)
1032 : {
1033 923478 : ulong d = perm_sign(P) == 1? 1: p-1;
1034 923489 : long i, r = lg(R);
1035 5729044 : for (i = 1; i < r; i++)
1036 4805571 : d = Fl_mul_pre(d, ucoeff(U, i, i), p, pi);
1037 923473 : *detp = d;
1038 : }
1039 1092734 : return X;
1040 : }
1041 :
1042 : static GEN
1043 169254 : Flm_gauss_CUP(GEN a, GEN b, ulong *detp, ulong p) {
1044 : GEN R, C, U, P;
1045 169254 : long n = lg(a) - 1, r;
1046 169254 : ulong pi = get_Fl_red(p);
1047 169254 : if (nbrows(a) < n || (r = Flm_CUP_pre(a, &R, &C, &U, &P, p, pi)) < n)
1048 14 : return NULL;
1049 169240 : return Flm_gauss_from_CUP(b, R, C, U, P, p, pi, detp);
1050 : }
1051 :
1052 : GEN
1053 2392265 : Flm_gauss_sp(GEN a, GEN b, ulong *detp, ulong p) {
1054 2392265 : pari_sp av = avma;
1055 : GEN x;
1056 2392265 : if (lg(a) - 1 >= Flm_CUP_LIMIT)
1057 48430 : x = Flm_gauss_CUP(a, b, detp, p);
1058 : else
1059 2343835 : x = Flm_gauss_sp_i(a, b, detp, p);
1060 2392267 : if (!x) return gc_NULL(av);
1061 2392260 : return gc_upto(av, x);
1062 : }
1063 :
1064 : GEN
1065 2327216 : Flm_gauss(GEN a, GEN b, ulong p) {
1066 2327216 : pari_sp av = avma;
1067 : GEN x;
1068 2327216 : if (lg(a) - 1 >= Flm_CUP_LIMIT)
1069 104786 : x = Flm_gauss_CUP(a, b, NULL, p);
1070 : else {
1071 2222430 : a = RgM_shallowcopy(a);
1072 2222429 : b = RgM_shallowcopy(b);
1073 2222429 : x = Flm_gauss_sp(a, b, NULL, p);
1074 : }
1075 2327219 : if (!x) return gc_NULL(av);
1076 2327205 : return gc_upto(av, x);
1077 : }
1078 :
1079 : static GEN
1080 65469 : Flm_inv_i(GEN a, ulong *detp, ulong p, long inplace) {
1081 65469 : pari_sp av = avma;
1082 65469 : long n = lg(a) - 1;
1083 : GEN b, x;
1084 65469 : if (n == 0) return cgetg(1, t_MAT);
1085 65469 : b = matid_Flm(nbrows(a));
1086 65469 : if (n >= Flm_CUP_LIMIT)
1087 16038 : x = Flm_gauss_CUP(a, b, detp, p);
1088 : else {
1089 49431 : if (!inplace)
1090 47835 : a = RgM_shallowcopy(a);
1091 49431 : x = Flm_gauss_sp(a, b, detp, p);
1092 : }
1093 65468 : if (!x) return gc_NULL(av);
1094 65461 : return gc_upto(av, x);
1095 : }
1096 :
1097 : GEN
1098 1827 : Flm_inv_sp(GEN a, ulong *detp, ulong p) {
1099 1827 : return Flm_inv_i(a, detp, p, 1);
1100 : }
1101 :
1102 : GEN
1103 63642 : Flm_inv(GEN a, ulong p) {
1104 63642 : return Flm_inv_i(a, NULL, p, 0);
1105 : }
1106 :
1107 : GEN
1108 21 : Flm_Flc_gauss(GEN a, GEN b, ulong p) {
1109 21 : pari_sp av = avma;
1110 21 : GEN z = Flm_gauss(a, mkmat(b), p);
1111 21 : if (!z) return gc_NULL(av);
1112 14 : if (lg(z) == 1) retgc_const(av, cgetg(1, t_VECSMALL));
1113 14 : return gc_uptoleaf(av, gel(z,1));
1114 : }
1115 :
1116 : GEN
1117 923504 : Flm_adjoint(GEN A, ulong p)
1118 : {
1119 923504 : pari_sp av = avma;
1120 : GEN R, C, U, P, C1, U1, v, c, d;
1121 923504 : long r, i, q, n = lg(A)-1, m;
1122 : ulong D;
1123 923504 : ulong pi = get_Fl_red(p);
1124 923502 : if (n == 0) return cgetg(1, t_MAT);
1125 923502 : r = Flm_CUP_pre(A, &R, &C, &U, &P, p, pi);
1126 923491 : m = nbrows(A);
1127 923488 : if (r == n)
1128 : {
1129 923474 : GEN X = Flm_gauss_from_CUP(matid_Flm(m), R, C, U, P, p, pi, &D);
1130 923491 : return gc_upto(av, Flm_Fl_mul_pre(X, D, p, pi));
1131 : }
1132 14 : if (r < n-1) return zero_Flm(n, m);
1133 28 : for (q = n, i = 1; i < n; i++)
1134 14 : if (R[i] != i) { q = i; break; }
1135 14 : C1 = matslice(C, 1, q-1, 1, q-1);
1136 14 : c = vecslice(Flm_row(C, q), 1, q-1);
1137 14 : c = Flm_lsolve_lower_unit_pre(C1, Flm_transpose(mkmat(c)), p, pi);
1138 14 : d = cgetg(m+1, t_VECSMALL);
1139 28 : for (i=1; i<q; i++) uel(d,i) = ucoeff(c,1,i);
1140 14 : uel(d,q) = p-1;
1141 21 : for (i=q+1; i<=m; i++) uel(d,i) = 0;
1142 14 : U1 = vecslice(U, 1, n-1);
1143 14 : v = gel(Flm_rsolve_upper_pre(U1, mkmat(gel(U,n)), p, pi),1);
1144 14 : v = vecsmall_append(v, p-1);
1145 14 : D = perm_sign(P) != (odd(q+n)?-1:1) ? p-1 : 1;
1146 28 : for (i = 1; i <= n-1; i++)
1147 14 : D = Fl_mul_pre(D, ucoeff(U1, i, i), p, pi);
1148 14 : d = Flv_Fl_mul(d, D, p);
1149 14 : return rowpermute(Flc_Flv_mul(v, d, p),perm_inv(P));
1150 : }
1151 :
1152 : static GEN
1153 287 : Flm_invimage_CUP(GEN A, GEN B, ulong p) {
1154 287 : pari_sp av = avma;
1155 : GEN R, Rc, C, U, P, B1, B2, C1, C2, X, Y, Z;
1156 : long r;
1157 287 : ulong pi = get_Fl_red(p);
1158 287 : r = Flm_CUP_pre(A, &R, &C, &U, &P, p, pi);
1159 287 : Rc = indexcompl(R, nbrows(B));
1160 287 : C1 = rowpermute(C, R);
1161 287 : C2 = rowpermute(C, Rc);
1162 287 : B1 = rowpermute(B, R);
1163 287 : B2 = rowpermute(B, Rc);
1164 287 : Z = Flm_rsolve_lower_unit_pre(C1, B1, p, pi);
1165 287 : if (!gequal(Flm_mul_pre(C2, Z, p, pi), B2))
1166 14 : return NULL;
1167 273 : Y = vconcat(Flm_rsolve_upper_pre(vecslice(U, 1, r), Z, p, pi),
1168 273 : zero_Flm(lg(A) - 1 - r, lg(B) - 1));
1169 273 : X = rowpermute(Y, perm_inv(P));
1170 273 : return gc_upto(av, X);
1171 : }
1172 :
1173 : GEN
1174 931 : Flm_invimage_i(GEN A, GEN B, ulong p)
1175 : {
1176 : GEN d, x, X, Y;
1177 931 : long i, j, nY, nA = lg(A)-1, nB = lg(B)-1;
1178 :
1179 931 : if (!nB) return cgetg(1, t_MAT);
1180 784 : if (maxss(nA, nB) >= Flm_CUP_LIMIT && nbrows(B) >= Flm_CUP_LIMIT)
1181 287 : return Flm_invimage_CUP(A, B, p);
1182 :
1183 497 : x = Flm_ker(shallowconcat(Flm_neg(A,p), B), p);
1184 : /* AX = BY, Y in strict upper echelon form with pivots = 1.
1185 : * We must find T such that Y T = Id_nB then X T = Z. This exists iff
1186 : * Y has at least nB columns and full rank */
1187 497 : nY = lg(x)-1;
1188 497 : if (nY < nB) return NULL;
1189 497 : Y = rowslice(x, nA+1, nA+nB); /* nB rows */
1190 497 : d = cgetg(nB+1, t_VECSMALL);
1191 1778 : for (i = nB, j = nY; i >= 1; i--, j--)
1192 : {
1193 1295 : for (; j>=1; j--)
1194 1288 : if (coeff(Y,i,j)) { d[i] = j; break; }
1195 1288 : if (!j) return NULL;
1196 : }
1197 : /* reduce to the case Y square, upper triangular with 1s on diagonal */
1198 490 : Y = vecpermute(Y, d);
1199 490 : x = vecpermute(x, d);
1200 490 : X = rowslice(x, 1, nA);
1201 490 : return Flm_mul(X, Flm_inv_upper_1(Y,p), p);
1202 : }
1203 : GEN
1204 889 : Flm_invimage(GEN A, GEN B, ulong p)
1205 : {
1206 889 : pari_sp av = avma;
1207 889 : GEN X = Flm_invimage_i(A,B,p);
1208 889 : if (!X) return gc_NULL(av);
1209 889 : return gc_upto(av, X);
1210 : }
1211 :
1212 : GEN
1213 131998 : Flm_Flc_invimage(GEN A, GEN y, ulong p)
1214 : {
1215 131998 : pari_sp av = avma;
1216 131998 : long i, l = lg(A);
1217 : GEN M, x;
1218 : ulong t;
1219 :
1220 131998 : if (l==1) return NULL;
1221 131858 : if (lg(y) != lgcols(A)) pari_err_DIM("Flm_Flc_invimage");
1222 131858 : M = cgetg(l+1,t_MAT);
1223 1082936 : for (i=1; i<l; i++) gel(M,i) = gel(A,i);
1224 131858 : gel(M,l) = y; M = Flm_ker(M,p);
1225 131858 : i = lg(M)-1; if (!i) return gc_NULL(av);
1226 :
1227 128625 : x = gel(M,i); t = x[l];
1228 128625 : if (!t) return gc_NULL(av);
1229 :
1230 128618 : setlg(x,l); t = Fl_inv(Fl_neg(t,p),p);
1231 128618 : if (t!=1) x = Flv_Fl_mul(x, t, p);
1232 128618 : return gc_uptoleaf(av, x);
1233 : }
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