2008-06-25 03:33:36 -04:00
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/* mpz_fac_ui(result, n) -- Set RESULT to N!.
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Copyright 1991, 1993, 1994, 1995, 2000, 2001, 2002, 2003 Free Software
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Foundation, Inc.
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2009-10-19 01:56:13 -04:00
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Copyright 2009 Robert Gerbicz
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2008-06-25 03:33:36 -04:00
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2009-10-19 01:56:13 -04:00
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This file is part of the MPIR Library.
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The MPIR Library is free software; you can redistribute it and/or modify
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2008-06-25 03:33:36 -04:00
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version.
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2009-10-19 01:56:13 -04:00
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The MPIR Library is distributed in the hope that it will be useful, but
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2008-06-25 03:33:36 -04:00
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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2009-10-19 01:56:13 -04:00
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along with the MPIR Library; see the file COPYING.LIB. If not, write to
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2008-06-25 03:33:36 -04:00
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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2009-02-12 05:24:24 -05:00
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#include "mpir.h"
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2008-06-25 03:33:36 -04:00
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#include "gmp-impl.h"
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#include "longlong.h"
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2009-08-09 00:06:25 -04:00
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#ifndef MPZ_FAC_IS_TUNING
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2008-06-25 03:33:36 -04:00
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#include "fac_ui.h"
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2009-08-09 00:06:25 -04:00
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#endif
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2008-06-25 03:33:36 -04:00
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static void odd_product _PROTO ((unsigned long low, unsigned long high, mpz_t * st));
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static void ap_product_small _PROTO ((mpz_t ret, mp_limb_t start, mp_limb_t step, unsigned long count, unsigned long nm));
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2009-08-03 19:09:30 -04:00
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static void binary_splitting _PROTO ((mpz_ptr result,unsigned long int *a,unsigned long int L));
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static void large_mpz_fac_ui _PROTO ((mpz_ptr result, unsigned long int n));
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static unsigned long int ulsqrt _PROTO ((unsigned long int n));
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2008-06-25 03:33:36 -04:00
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/* must be >=2 */
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#define APCONST 5
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/* for single non-zero limb */
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#define MPZ_SET_1_NZ(z,n) \
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do { \
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mpz_ptr __z = (z); \
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ASSERT ((n) != 0); \
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PTR(__z)[0] = (n); \
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SIZ(__z) = 1; \
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} while (0)
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/* for src>0 and n>0 */
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#define MPZ_MUL_1_POS(dst,src,n) \
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do { \
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mpz_ptr __dst = (dst); \
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mpz_srcptr __src = (src); \
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mp_size_t __size = SIZ(__src); \
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mp_ptr __dst_p; \
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mp_limb_t __c; \
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\
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ASSERT (__size > 0); \
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ASSERT ((n) != 0); \
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\
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MPZ_REALLOC (__dst, __size+1); \
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__dst_p = PTR(__dst); \
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\
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__c = mpn_mul_1 (__dst_p, PTR(__src), __size, n); \
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__dst_p[__size] = __c; \
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SIZ(__dst) = __size + (__c != 0); \
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} while (0)
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#if BITS_PER_ULONG == BITS_PER_MP_LIMB
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#define BSWAP_ULONG(x,y) BSWAP_LIMB(x,y)
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#endif
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/* We used to have a case here for limb==2*long, doing a BSWAP_LIMB followed
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by a shift down to get the high part. But it provoked incorrect code
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from "HP aC++/ANSI C B3910B A.05.52 [Sep 05 2003]" in ILP32 mode. This
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case would have been nice for gcc ia64 where BSWAP_LIMB is a mux1, but we
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can get that directly muxing a 4-byte ulong if it matters enough. */
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#if ! defined (BSWAP_ULONG)
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#define BSWAP_ULONG(dst, src) \
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do { \
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unsigned long __bswapl_src = (src); \
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unsigned long __bswapl_dst = 0; \
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int __i; \
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for (__i = 0; __i < sizeof(unsigned long); __i++) \
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{ \
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__bswapl_dst = (__bswapl_dst << 8) | (__bswapl_src & 0xFF); \
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__bswapl_src >>= 8; \
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} \
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(dst) = __bswapl_dst; \
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} while (0)
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#endif
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/* x is bit reverse of y */
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/* Note the divides below are all exact */
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#define BITREV_ULONG(x,y) \
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do { \
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unsigned long __dst; \
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BSWAP_ULONG(__dst,y); \
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__dst = ((__dst>>4)&(ULONG_MAX/17)) | ((__dst<<4)&((ULONG_MAX/17)*16)); \
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__dst = ((__dst>>2)&(ULONG_MAX/5) ) | ((__dst<<2)&((ULONG_MAX/5)*4) ); \
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__dst = ((__dst>>1)&(ULONG_MAX/3) ) | ((__dst<<1)&((ULONG_MAX/3)*2) ); \
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(x) = __dst; \
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} while(0)
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/* above could be improved if cpu has a nibble/bit swap/muxing instruction */
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/* above code is serialized, possible to write as a big parallel expression */
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void
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mpz_fac_ui (mpz_ptr x, unsigned long n)
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{
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unsigned long z, stt;
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int i, j;
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mpz_t t1, st[8 * sizeof (unsigned long) + 1 - APCONST];
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mp_limb_t d[4];
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static const mp_limb_t table[] = { ONE_LIMB_FACTORIAL_TABLE };
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if (n < numberof (table))
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{
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MPZ_SET_1_NZ (x, table[n]);
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return;
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}
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/* NOTE : MUST have n>=3 here */
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ASSERT (n >= 3);
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/* for estimating the alloc sizes the calculation of these formula's is not
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exact and also the formulas are only approximations, also we ignore
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the few "side" calculations, correct allocation seems to speed up the
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small sizes better, having very little effect on the large sizes */
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/* estimate space for stack entries see below
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number of bits for n! is
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(1+log_2(2*pi)/2)-n*log_2(exp(1))+(n+1/2)*log_2(n)=
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2.325748065-n*1.442695041+(n+0.5)*log_2(n) */
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umul_ppmm (d[1], d[0], (mp_limb_t) n, (mp_limb_t) FAC2OVERE);
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/* d[1] is 2n/e, d[0] ignored */
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count_leading_zeros (z, d[1]);
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z = GMP_LIMB_BITS - z - 1; /* z=floor(log_2(2n/e)) */
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umul_ppmm (d[1], d[0], (mp_limb_t) n, (mp_limb_t) z);
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/* d=n*floor(log_2(2n/e)) */
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d[0] = (d[0] >> 2) | (d[1] << (GMP_LIMB_BITS - 2));
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d[1] >>= 2;
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/* d=n*floor(log_2(2n/e))/4 */
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z = d[0] + 1; /* have to ignore any overflow */
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/* so z is the number of bits wanted for st[0] */
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if (n <= ((unsigned long) 1) << (APCONST))
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{
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mpz_realloc2 (x, 4 * z);
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ap_product_small (x, CNST_LIMB(2), CNST_LIMB(1), n - 1, 4L);
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return;
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}
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if (n <= ((unsigned long) 1) << (APCONST + 1))
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{ /* use n!=odd(1,n)*(n/2)!*2^(n/2) */
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mpz_init2 (t1, 2 * z);
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mpz_realloc2 (x, 4 * z);
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ap_product_small (x, CNST_LIMB(2), CNST_LIMB(1), n / 2 - 1, 4L);
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ap_product_small (t1, CNST_LIMB(3), CNST_LIMB(2), (n - 1) / 2, 4L);
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mpz_mul (x, x, t1);
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mpz_clear (t1);
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mpz_mul_2exp (x, x, n / 2);
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return;
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}
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if (n <= ((unsigned long) 1) << (APCONST + 2))
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{
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/* use n!=C_2(1,n/2)^2*C_2(n/2,n)*(n/4)!*2^(n/2+n/4) all int divs
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so need (BITS_IN_N-APCONST+1)=(APCONST+3-APCONST+1)=4 stack entries */
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mpz_init2 (t1, 2 * z);
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mpz_realloc2 (x, 4 * z);
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for (i = 0; i < 4; i++)
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{
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mpz_init2 (st[i], z);
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z >>= 1;
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}
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odd_product (1, n / 2, st);
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mpz_set (x, st[0]);
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odd_product (n / 2, n, st);
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mpz_mul (x, x, x);
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ASSERT (n / 4 <= FACMUL4 + 6);
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ap_product_small (t1, CNST_LIMB(2), CNST_LIMB(1), n / 4 - 1, 4L);
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/* must have 2^APCONST odd numbers max */
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mpz_mul (t1, t1, st[0]);
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for (i = 0; i < 4; i++)
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mpz_clear (st[i]);
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mpz_mul (x, x, t1);
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mpz_clear (t1);
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mpz_mul_2exp (x, x, n / 2 + n / 4);
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return;
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}
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2009-08-03 19:09:30 -04:00
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if (ABOVE_THRESHOLD(n,FAC_UI_THRESHOLD)){large_mpz_fac_ui(x,n);return;}
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2008-06-25 03:33:36 -04:00
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count_leading_zeros (stt, (mp_limb_t) n);
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stt = GMP_LIMB_BITS - stt + 1 - APCONST;
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for (i = 0; i < (signed long) stt; i++)
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{
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mpz_init2 (st[i], z);
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z >>= 1;
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}
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count_leading_zeros (z, (mp_limb_t) (n / 3));
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/* find z st 2^z>n/3 range for z is 1 <= z <= 8 * sizeof(unsigned long)-1 */
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z = GMP_LIMB_BITS - z;
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/*
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n! = 2^e * PRODUCT_{i=0}^{i=z-1} C_2( n/2^{i+1}, n/2^i )^{i+1}
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where 2^e || n! 3.2^z>n C_2(a,b)=PRODUCT of odd z such that a<z<=b
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*/
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mpz_init_set_ui (t1, 1);
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for (j = 8 * sizeof (unsigned long) / 2; j != 0; j >>= 1)
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{
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MPZ_SET_1_NZ (x, 1);
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for (i = 8 * sizeof (unsigned long) - j; i >= j; i -= 2 * j)
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if ((signed long) z >= i)
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{
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odd_product (n >> i, n >> (i - 1), st);
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/* largest odd product when j=i=1 then we have
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odd_product(n/2,n,st) which is approx (2n/e)^(n/4)
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so log_base2(largest oddproduct)=n*log_base2(2n/e)/4
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number of bits is n*log_base2(2n/e)/4+1 */
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if (i != j)
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mpz_pow_ui (st[0], st[0], i / j);
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mpz_mul (x, x, st[0]);
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}
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if ((signed long) z >= j && j != 1)
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{
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mpz_mul (t1, t1, x);
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mpz_mul (t1, t1, t1);
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}
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}
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for (i = 0; i < (signed long) stt; i++)
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mpz_clear (st[i]);
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mpz_mul (x, x, t1);
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mpz_clear (t1);
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popc_limb (i, (mp_limb_t) n);
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mpz_mul_2exp (x, x, n - i);
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return;
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}
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/* start,step are mp_limb_t although they will fit in unsigned long */
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static void
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ap_product_small (mpz_t ret, mp_limb_t start, mp_limb_t step,
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unsigned long count, unsigned long nm)
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{
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unsigned long a;
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mp_limb_t b;
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ASSERT (count <= (((unsigned long) 1) << APCONST));
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/* count can never be zero ? check this and remove test below */
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if (count == 0)
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{
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MPZ_SET_1_NZ (ret, 1);
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return;
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}
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if (count == 1)
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{
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MPZ_SET_1_NZ (ret, start);
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return;
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}
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switch (nm)
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{
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case 1:
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MPZ_SET_1_NZ (ret, start);
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b = start + step;
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for (a = 0; a < count - 1; b += step, a++)
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MPZ_MUL_1_POS (ret, ret, b);
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return;
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case 2:
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MPZ_SET_1_NZ (ret, start * (start + step));
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if (count == 2)
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return;
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for (b = start + 2 * step, a = count / 2 - 1; a != 0;
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a--, b += 2 * step)
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MPZ_MUL_1_POS (ret, ret, b * (b + step));
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if (count % 2 == 1)
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MPZ_MUL_1_POS (ret, ret, b);
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return;
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case 3:
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if (count == 2)
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{
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MPZ_SET_1_NZ (ret, start * (start + step));
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return;
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}
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MPZ_SET_1_NZ (ret, start * (start + step) * (start + 2 * step));
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if (count == 3)
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return;
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for (b = start + 3 * step, a = count / 3 - 1; a != 0;
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a--, b += 3 * step)
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MPZ_MUL_1_POS (ret, ret, b * (b + step) * (b + 2 * step));
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if (count % 3 == 2)
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b = b * (b + step);
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if (count % 3 != 0)
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MPZ_MUL_1_POS (ret, ret, b);
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return;
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default: /* ie nm=4 */
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if (count == 2)
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{
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MPZ_SET_1_NZ (ret, start * (start + step));
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return;
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}
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if (count == 3)
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{
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MPZ_SET_1_NZ (ret, start * (start + step) * (start + 2 * step));
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return;
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}
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MPZ_SET_1_NZ (ret,
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start * (start + step) * (start + 2 * step) * (start +
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3 * step));
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if (count == 4)
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return;
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for (b = start + 4 * step, a = count / 4 - 1; a != 0;
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|
a--, b += 4 * step)
|
|
|
|
MPZ_MUL_1_POS (ret, ret,
|
|
|
|
b * (b + step) * (b + 2 * step) * (b + 3 * step));
|
|
|
|
if (count % 4 == 2)
|
|
|
|
b = b * (b + step);
|
|
|
|
if (count % 4 == 3)
|
|
|
|
b = b * (b + step) * (b + 2 * step);
|
|
|
|
if (count % 4 != 0)
|
|
|
|
MPZ_MUL_1_POS (ret, ret, b);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/* return value in st[0]
|
|
|
|
odd_product(l,h)=sqrt((h/e)^h/(l/e)^l) using Stirling approx and e=exp(1)
|
|
|
|
so st[0] needs enough bits for above, st[1] needs half these bits and
|
|
|
|
st[2] needs 1/4 of these bits etc */
|
|
|
|
static void
|
|
|
|
odd_product (unsigned long low, unsigned long high, mpz_t * st)
|
|
|
|
{
|
|
|
|
unsigned long stc = 1, stn = 0, n, y, mask, a, nm = 1;
|
|
|
|
signed long z;
|
|
|
|
|
|
|
|
low++;
|
|
|
|
if (low % 2 == 0)
|
|
|
|
low++;
|
|
|
|
if (high == 0)
|
|
|
|
high = 1;
|
|
|
|
if (high % 2 == 0)
|
|
|
|
high--;
|
|
|
|
/* must have high>=low ? check this and remove test below */
|
|
|
|
if (high < low)
|
|
|
|
{
|
|
|
|
MPZ_SET_1_NZ (st[0], 1);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
if (high == low)
|
|
|
|
{
|
|
|
|
MPZ_SET_1_NZ (st[0], low);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
if (high <= FACMUL2 + 2)
|
|
|
|
{
|
|
|
|
nm = 2;
|
|
|
|
if (high <= FACMUL3 + 4)
|
|
|
|
{
|
|
|
|
nm = 3;
|
|
|
|
if (high <= FACMUL4 + 6)
|
|
|
|
nm = 4;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
high = (high - low) / 2 + 1; /* high is now count,high<=2^(BITS_PER_ULONG-1) */
|
|
|
|
if (high <= (((unsigned long) 1) << APCONST))
|
|
|
|
{
|
|
|
|
ap_product_small (st[0], (mp_limb_t) low, CNST_LIMB(2), high, nm);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
count_leading_zeros (n, (mp_limb_t) high);
|
|
|
|
/* assumes clz above is LIMB based not NUMB based */
|
|
|
|
n = GMP_LIMB_BITS - n - APCONST;
|
|
|
|
mask = (((unsigned long) 1) << n);
|
|
|
|
a = mask << 1;
|
|
|
|
mask--;
|
|
|
|
/* have 2^(BITS_IN_N-APCONST) iterations so need
|
|
|
|
(BITS_IN_N-APCONST+1) stack entries */
|
|
|
|
for (z = mask; z >= 0; z--)
|
|
|
|
{
|
|
|
|
BITREV_ULONG (y, z);
|
|
|
|
y >>= (BITS_PER_ULONG - n);
|
|
|
|
ap_product_small (st[stn],
|
|
|
|
(mp_limb_t) (low + 2 * ((~y) & mask)), (mp_limb_t) a,
|
|
|
|
(high + y) >> n, nm);
|
|
|
|
ASSERT (((high + y) >> n) <= (((unsigned long) 1) << APCONST));
|
|
|
|
stn++;
|
|
|
|
y = stc++;
|
|
|
|
while ((y & 1) == 0)
|
|
|
|
{
|
|
|
|
mpz_mul (st[stn - 2], st[stn - 2], st[stn - 1]);
|
|
|
|
stn--;
|
|
|
|
y >>= 1;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
ASSERT (stn == 1);
|
|
|
|
return;
|
|
|
|
}
|
2009-08-03 19:09:30 -04:00
|
|
|
|
|
|
|
|
|
|
|
// Computation of n factorial by computing the prime factoriation of n!,
|
|
|
|
// using iterated squaring and multiplication by a "small" number idea and binary splitting
|
|
|
|
// written by Robert Gerbicz
|
|
|
|
|
|
|
|
static void binary_splitting (mpz_ptr result,unsigned long int *a,unsigned long int L) {
|
|
|
|
// mulptiplication by binary splitting
|
|
|
|
unsigned long int i,L0,L1;
|
|
|
|
mpz_t temp;
|
|
|
|
|
|
|
|
if(L==0) {
|
|
|
|
mpz_set_ui (result, 1);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
if(L<=3) {
|
|
|
|
mpz_set_ui(result,a[0]);
|
|
|
|
for(i=1;i<L;i++)
|
|
|
|
mpz_mul_ui(result,result,a[i]);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
L0=L/2;
|
|
|
|
L1=L-L0;
|
|
|
|
binary_splitting(result,a,L1);
|
|
|
|
mpz_init(temp);
|
|
|
|
binary_splitting(temp,a+L1,L0);
|
|
|
|
mpz_mul(result,result,temp);
|
|
|
|
mpz_clear(temp);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
static unsigned long int ulsqrt(unsigned long int n)
|
|
|
|
{unsigned long int x,y;
|
|
|
|
|
|
|
|
x=y=n;
|
|
|
|
do{x=y;
|
|
|
|
y=(n/x+x)/2;
|
|
|
|
}while(y<x);
|
|
|
|
return x;}
|
|
|
|
|
|
|
|
static void large_mpz_fac_ui(mpz_ptr result, unsigned long int n) {
|
|
|
|
unsigned long int Bit[32],e,N,g,p2,*S,*exponent,*isprime,*primes,count,i,p,primepi,sq,n2=(n-1)>>1,n64=(n>>6)+1,memalloc;
|
|
|
|
int h,expo;
|
|
|
|
mpz_t temp;
|
|
|
|
mpz_init(temp);
|
|
|
|
isprime=__GMP_ALLOCATE_FUNC_TYPE(n64,unsigned long int);
|
|
|
|
ASSERT(n>=2);// cant handle n<2
|
|
|
|
Bit[0]=1;
|
|
|
|
for(i=1;i<32;i++) Bit[i]=Bit[i-1]<<1; // Bit[i]=2^i
|
|
|
|
|
|
|
|
// determine all odd primes up to n by sieve
|
|
|
|
for(i=0;i<n64;i++) isprime[i]=0xffffffff;
|
|
|
|
|
|
|
|
sq=ulsqrt(n)+1;
|
|
|
|
for(p=3;p<=sq;p+=2) {
|
|
|
|
if(isprime[p>>6]&Bit[(p>>1)&31]) {
|
|
|
|
for(i=(p*p-1)>>1;i<=n2;i+=p) isprime[i>>5]&=~Bit[i&31];
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
primepi=0;
|
|
|
|
for(i=0;i<=n2;i++)
|
|
|
|
primepi+=((isprime[i>>5]&Bit[i&31])>0);
|
|
|
|
|
|
|
|
memalloc=primepi;
|
|
|
|
primes=__GMP_ALLOCATE_FUNC_TYPE(memalloc,unsigned long int);
|
|
|
|
S=__GMP_ALLOCATE_FUNC_TYPE(memalloc,unsigned long int);
|
|
|
|
exponent=__GMP_ALLOCATE_FUNC_TYPE(memalloc,unsigned long int);
|
|
|
|
|
|
|
|
primepi=0;
|
|
|
|
// 1 is not prime and hasn't cancelled, so start from 1*2+1=3
|
|
|
|
for(i=1;i<=n2;i++)
|
|
|
|
if((isprime[i>>5]&Bit[i&31])>0) {
|
|
|
|
p=2*i+1;
|
|
|
|
N=n;
|
|
|
|
e=0;
|
|
|
|
while(N) N/=p,e+=N;
|
|
|
|
primes[primepi]=p; // store prime
|
|
|
|
exponent[primepi]=e; // exponent of p in the factorization of n!
|
|
|
|
primepi++;
|
|
|
|
}
|
|
|
|
|
|
|
|
__GMP_FREE_FUNC_TYPE(isprime,n64,unsigned long int);
|
|
|
|
|
|
|
|
mpz_set_ui(result,1);
|
|
|
|
|
|
|
|
expo=0,p2=1;
|
|
|
|
N=n;
|
|
|
|
while(N) N>>=1,p2<<=1,expo++;
|
|
|
|
for(h=expo;h>=0;h--) {
|
|
|
|
// collect all primes for which in the factorization of n! the primes[g]'s exponent's h-th bit is 1
|
|
|
|
count=0;
|
|
|
|
// note that exponent[] is a decreasing array
|
|
|
|
for(g=0;(g<primepi)&&(exponent[g]>=p2);g++)
|
|
|
|
if(((exponent[g]>>h)&1)==1) {
|
|
|
|
S[count]=primes[g];
|
|
|
|
count++;
|
|
|
|
}
|
|
|
|
binary_splitting(temp,S,count); // build the product by binary splitting
|
|
|
|
mpz_pow_ui(result,result,2); // squaring
|
|
|
|
mpz_mul(result,result,temp); // multiplcation by a not so large number
|
|
|
|
p2>>=1;
|
|
|
|
}
|
|
|
|
|
|
|
|
N=n;
|
|
|
|
e=0;
|
|
|
|
while(N) N>>=1,e+=N;
|
|
|
|
mpz_mul_2exp(result,result,e); // shift the number to finally get n!
|
|
|
|
|
|
|
|
__GMP_FREE_FUNC_TYPE(S,memalloc,unsigned long int);
|
|
|
|
__GMP_FREE_FUNC_TYPE(primes,memalloc,unsigned long int);
|
|
|
|
__GMP_FREE_FUNC_TYPE(exponent,memalloc,unsigned long int);
|
|
|
|
mpz_clear(temp);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
|