diff options
Diffstat (limited to 'gmp-6.3.0/mpz/mfac_uiui.c')
| -rw-r--r-- | gmp-6.3.0/mpz/mfac_uiui.c | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/gmp-6.3.0/mpz/mfac_uiui.c b/gmp-6.3.0/mpz/mfac_uiui.c new file mode 100644 index 0000000..8595a9b --- /dev/null +++ b/gmp-6.3.0/mpz/mfac_uiui.c @@ -0,0 +1,140 @@ +/* mpz_mfac_uiui(RESULT, N, M) -- Set RESULT to N!^(M) = N(N-M)(N-2M)... + +Contributed to the GNU project by Marco Bodrato. + +Copyright 2012, 2013, 2015, 2016 Free Software Foundation, Inc. + +This file is part of the GNU MP Library. + +The GNU MP Library is free software; you can redistribute it and/or modify +it under the terms of either: + + * the GNU Lesser General Public License as published by the Free + Software Foundation; either version 3 of the License, or (at your + option) any later version. + +or + + * 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. + +or both in parallel, as here. + +The GNU MP Library 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 copies of the GNU General Public License and the +GNU Lesser General Public License along with the GNU MP Library. If not, +see https://www.gnu.org/licenses/. */ + +#include "gmp-impl.h" + +/*************************************************************/ +/* Section macros: common macros, for swing/fac/bin (&sieve) */ +/*************************************************************/ + +#define FACTOR_LIST_STORE(P, PR, MAX_PR, VEC, I) \ + do { \ + if ((PR) > (MAX_PR)) { \ + (VEC)[(I)++] = (PR); \ + (PR) = (P); \ + } else \ + (PR) *= (P); \ + } while (0) + +/*********************************************************/ +/* Section oder factorials: */ +/*********************************************************/ + +/* mpz_mfac_uiui (x, n, m) computes x = n!^(m) = n*(n-m)*(n-2m)*... */ + +void +mpz_mfac_uiui (mpz_ptr x, unsigned long n, unsigned long m) +{ + ASSERT (n <= GMP_NUMB_MAX); + ASSERT (m != 0); + + if ((n < 3) | (n - 3 < m - 1)) { /* (n < 3 || n - 1 <= m || m == 0) */ + MPZ_NEWALLOC (x, 1)[0] = n + (n == 0); + SIZ (x) = 1; + } else { /* 0 < m < n - 1 < GMP_NUMB_MAX */ + mp_limb_t g, sn; + mpz_t t; + + sn = n; + g = mpn_gcd_1 (&sn, 1, m); + if (g > 1) { n/=g; m/=g; } + + if (m <= 2) { /* fac or 2fac */ + if (m == 1) { + if (g > 2) { + mpz_init (t); + mpz_fac_ui (t, n); + sn = n; + } else { + if (g == 2) + mpz_2fac_ui (x, n << 1); + else + mpz_fac_ui (x, n); + return; + } + } else { /* m == 2 */ + if (g > 1) { + mpz_init (t); + mpz_2fac_ui (t, n); + sn = n / 2 + 1; + } else { + mpz_2fac_ui (x, n); + return; + } + } + } else { /* m >= 3, gcd(n,m) = 1 */ + mp_limb_t *factors; + mp_limb_t prod, max_prod; + mp_size_t j; + TMP_DECL; + + sn = n / m + 1; + + j = 0; + prod = n; + n -= m; + max_prod = GMP_NUMB_MAX / n; + + if (g > 1) + factors = MPZ_NEWALLOC (x, sn / log_n_max (n) + 2); + else { + TMP_MARK; + factors = TMP_ALLOC_LIMBS (sn / log_n_max (n) + 2); + } + + for (; n > m; n -= m) + FACTOR_LIST_STORE (n, prod, max_prod, factors, j); + + factors[j++] = n; + factors[j++] = prod; + + if (g > 1) { + mpz_init (t); + mpz_prodlimbs (t, factors, j); + } else { + mpz_prodlimbs (x, factors, j); + TMP_FREE; + return; + } + } + + { + mpz_t p; + + mpz_init (p); + mpz_ui_pow_ui (p, g, sn); /* g^sn */ + mpz_mul (x, p, t); + mpz_clear (p); + mpz_clear (t); + } + } +} |