source: git/factory/cf_hnf.h @ 362fc67

jengelh-datetimespielwiese
Last change on this file since 362fc67 was 362fc67, checked in by Martin Lee <martinlee84@…>, 11 years ago
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1/* emacs edit mode for this file is -*- C++ -*- */
2#ifndef CF_HNF_H
3#define CF_HNF_H
4
5/*BEGINPUBLIC*/
6
7#ifdef HAVE_NTL
8
9//{{{ docu
10//
11// The input matrix A is square matrix of integers
12// output: the Hermite Normal Form of A; that is,
13// the unique m x m matrix whose rows span L, such that
14//
15// - lower triangular,
16// - the diagonal entries are positive,
17// - any entry below the diagonal is a non-negative number
18//   strictly less than the diagonal entry in its column.
19//
20// via NTL:HNF
21//
22//}}}
23
24CFMatrix* cf_HNF(CFMatrix& A);
25
26// performs LLL reduction.
27
28// B is an m x n matrix, viewed as m rows of n-vectors.  m may be less
29// than, equal to, or greater than n, and the rows need not be
30// linearly independent.  B is transformed into an LLL-reduced basis,
31// and the return value is the rank r of B.  The first m-r rows of B
32// are zero. 
33
34// More specifically, elementary row transformations are performed on
35// B so that the non-zero rows of new-B form an LLL-reduced basis
36// for the lattice spanned by the rows of old-B.
37// The default reduction parameter is delta=3/4, which means
38// that the squared length of the first non-zero basis vector
39// is no more than 2^{r-1} times that of the shortest vector in
40// the lattice.
41
42CFMatrix* cf_LLL(CFMatrix& A);
43
44#endif
45
46/*ENDPUBLIC*/
47
48#endif
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