~/ntl-11.4.2/doc/HNF.cpp.html

    /**************************************************************************\

    MODULE: HNF

    SUMMARY:

    A routine for computing Hermite Normal Forms

    \**************************************************************************/

    #include <NTL/mat_ZZ.h>

    void HNF(mat_ZZ& W, const mat_ZZ& A, const ZZ& D);

    // The input matrix A is an n x m matrix of rank m (so n >= m), and D
    // is a multiple of the determinant of the lattice L spanned by the
    // rows of A.  W is computed as the Hermite Normal Form of A; that is,
    // W is the unique m x m matrix whose rows span L, such that

    //   - W is lower triangular,
    //   - the diagonal entries are positive,
    //   - any entry below the diagonal is a non-negative number
    //     strictly less than the diagonal entry in its column.

    // Currently, this is implemented using the algorithm of [P. Domich,
    // R. Kannan and L. Trotter, Math. Oper. Research 12:50-59, 1987].