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source:
trunk/third/gmp/mpz/sqrt.c
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18191

Revision 18191, 2.4 KB checked in by ghudson, 22 years ago (diff) |
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1 | /* mpz_sqrt(root, u) -- Set ROOT to floor(sqrt(U)). |

2 | |

3 | Copyright 1991, 1993, 1994, 1996, 2000, 2001 Free Software Foundation, Inc. |

4 | |

5 | This file is part of the GNU MP Library. |

6 | |

7 | The GNU MP Library is free software; you can redistribute it and/or modify |

8 | it under the terms of the GNU Lesser General Public License as published by |

9 | the Free Software Foundation; either version 2.1 of the License, or (at your |

10 | option) any later version. |

11 | |

12 | The GNU MP Library is distributed in the hope that it will be useful, but |

13 | WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |

14 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |

15 | License for more details. |

16 | |

17 | You should have received a copy of the GNU Lesser General Public License |

18 | along with the GNU MP Library; see the file COPYING.LIB. If not, write to |

19 | the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |

20 | MA 02111-1307, USA. */ |

21 | |

22 | #include <stdio.h> /* for NULL */ |

23 | #include "gmp.h" |

24 | #include "gmp-impl.h" |

25 | |

26 | void |

27 | mpz_sqrt (mpz_ptr root, mpz_srcptr op) |

28 | { |

29 | mp_size_t op_size, root_size; |

30 | mp_ptr root_ptr, op_ptr; |

31 | mp_ptr free_me = NULL; |

32 | mp_size_t free_me_size; |

33 | TMP_DECL (marker); |

34 | |

35 | TMP_MARK (marker); |

36 | op_size = op->_mp_size; |

37 | if (op_size <= 0) |

38 | { |

39 | if (op_size < 0) |

40 | SQRT_OF_NEGATIVE; |

41 | SIZ(root) = 0; |

42 | return; |

43 | } |

44 | |

45 | /* The size of the root is accurate after this simple calculation. */ |

46 | root_size = (op_size + 1) / 2; |

47 | |

48 | root_ptr = root->_mp_d; |

49 | op_ptr = op->_mp_d; |

50 | |

51 | if (root->_mp_alloc < root_size) |

52 | { |

53 | if (root_ptr == op_ptr) |

54 | { |

55 | free_me = root_ptr; |

56 | free_me_size = root->_mp_alloc; |

57 | } |

58 | else |

59 | (*__gmp_free_func) (root_ptr, root->_mp_alloc * BYTES_PER_MP_LIMB); |

60 | |

61 | root->_mp_alloc = root_size; |

62 | root_ptr = (mp_ptr) (*__gmp_allocate_func) (root_size * BYTES_PER_MP_LIMB); |

63 | root->_mp_d = root_ptr; |

64 | } |

65 | else |

66 | { |

67 | /* Make OP not overlap with ROOT. */ |

68 | if (root_ptr == op_ptr) |

69 | { |

70 | /* ROOT and OP are identical. Allocate temporary space for OP. */ |

71 | op_ptr = (mp_ptr) TMP_ALLOC (op_size * BYTES_PER_MP_LIMB); |

72 | /* Copy to the temporary space. Hack: Avoid temporary variable |

73 | by using ROOT_PTR. */ |

74 | MPN_COPY (op_ptr, root_ptr, op_size); |

75 | } |

76 | } |

77 | |

78 | mpn_sqrtrem (root_ptr, NULL, op_ptr, op_size); |

79 | |

80 | root->_mp_size = root_size; |

81 | |

82 | if (free_me != NULL) |

83 | (*__gmp_free_func) (free_me, free_me_size * BYTES_PER_MP_LIMB); |

84 | TMP_FREE (marker); |

85 | } |

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