Module: ppl/ppl Branch: master Commit: 24b68b1c48e4552f1085d9a04979e610c8ca79ca URL: http://www.cs.unipr.it/git/gitweb.cgi?p=ppl/ppl.git;a=commit;h=24b68b1c48e45...

Author: Marco Poletti poletti.marco@gmail.com Date: Mon Feb 14 19:45:34 2011 +0100

PIP_Tree: avoid repeated calls to Sparse_Row::get(), in solve().

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src/PIP_Tree.cc | 9 ++++++--- 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/PIP_Tree.cc b/src/PIP_Tree.cc index 58fc66b..2660877 100644 --- a/src/PIP_Tree.cc +++ b/src/PIP_Tree.cc @@ -2643,20 +2643,23 @@ PIP_Solution_Node::solve(const PIP_Problem& pip, for (dimension_type i = num_rows; i-- > 0; ) { Row& s_i = tableau.s[i]; Row& t_i = tableau.t[i]; + Coefficient s_i_pj = s_i.get(pj); Row::iterator k = t_i.end(); for (Row::const_iterator j = t_pivot.begin(), j_end = t_pivot.end(); j != j_end; ++j) { Coefficient_traits::const_reference t_pivot_j = *j; // Do nothing if the j-th pivot element is zero. if (t_pivot_j != 0) { - /* NOTE: s_i[pj] needs to be recomputed at each iteration, - as it may have been modified by tableau.scale(). */ - product = t_pivot_j * s_i.get(pj); + product = t_pivot_j * s_i_pj; if (product % s_pivot_pj != 0) { // Must scale matrix to stay in integer case. gcd_assign(gcd, product, s_pivot_pj); exact_div_assign(scale_factor, s_pivot_pj, gcd); tableau.scale(scale_factor); + // s_i[pj] has been modified by scale(), so s_i_pj must be + // updated. + s_i_pj *= scale_factor; + PPL_ASSERT(s_i.get(pj) == s_i_pj); product *= scale_factor; } PPL_ASSERT(product % s_pivot_pj == 0);