sqrt.c
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上传日期:2022-08-06
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- /* mpz_sqrt(root, u) -- Set ROOT to floor(sqrt(U)).
- Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2005 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 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.
- 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 Lesser General Public
- License for more details.
- You should have received a copy of the GNU Lesser General Public License
- along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
- #include <stdio.h> /* for NULL */
- #include "gmp.h"
- #include "gmp-impl.h"
- void
- mpz_sqrt (mpz_ptr root, mpz_srcptr op)
- {
- mp_size_t op_size, root_size;
- mp_ptr root_ptr, op_ptr;
- mp_ptr free_me = NULL;
- mp_size_t free_me_size;
- TMP_DECL;
- TMP_MARK;
- op_size = op->_mp_size;
- if (op_size <= 0)
- {
- if (op_size < 0)
- SQRT_OF_NEGATIVE;
- SIZ(root) = 0;
- return;
- }
- /* The size of the root is accurate after this simple calculation. */
- root_size = (op_size + 1) / 2;
- root_ptr = root->_mp_d;
- op_ptr = op->_mp_d;
- if (root->_mp_alloc < root_size)
- {
- if (root_ptr == op_ptr)
- {
- free_me = root_ptr;
- free_me_size = root->_mp_alloc;
- }
- else
- (*__gmp_free_func) (root_ptr, root->_mp_alloc * BYTES_PER_MP_LIMB);
- root->_mp_alloc = root_size;
- root_ptr = (mp_ptr) (*__gmp_allocate_func) (root_size * BYTES_PER_MP_LIMB);
- root->_mp_d = root_ptr;
- }
- else
- {
- /* Make OP not overlap with ROOT. */
- if (root_ptr == op_ptr)
- {
- /* ROOT and OP are identical. Allocate temporary space for OP. */
- op_ptr = TMP_ALLOC_LIMBS (op_size);
- /* Copy to the temporary space. Hack: Avoid temporary variable
- by using ROOT_PTR. */
- MPN_COPY (op_ptr, root_ptr, op_size);
- }
- }
- mpn_sqrtrem (root_ptr, NULL, op_ptr, op_size);
- root->_mp_size = root_size;
- if (free_me != NULL)
- (*__gmp_free_func) (free_me, free_me_size * BYTES_PER_MP_LIMB);
- TMP_FREE;
- }