Module: ppl/ppl Branch: pip Commit: 9a9a350ade225d3d28b848da2caa4ccb63a8e0d0 URL: http://www.cs.unipr.it/git/gitweb.cgi?p=ppl/ppl.git;a=commit;h=9a9a350ade225...

Author: François Galea francois.galea@uvsq.fr Date: Fri Oct 9 17:57:18 2009 +0200

Improved best pivot row selection heuristic.

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src/PIP_Tree.cc | 18 ++++++++++++++++++ 1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/src/PIP_Tree.cc b/src/PIP_Tree.cc index f52221b..7a470dd 100644 --- a/src/PIP_Tree.cc +++ b/src/PIP_Tree.cc @@ -1150,6 +1150,24 @@ PIP_Solution_Node::solve(PIP_Tree_Node*& parent_ref, const Matrix& ctx, std::cout << "Adding tautology: " << *c << std::endl; #endif } else { + /* Heuristically choose "best" pivoting row. */ + Coefficient score; + Coefficient best = 0; + dimension_type best_i = n_a_d; + for (i = i__; i < num_rows; ++i) { + if (sign[i] != MIXED) + continue; + const Row& row = tableau.t[i]; + score = 0; + for (j = 0; j < num_params; ++j) + score += row[j]; + if (best_i == n_a_d || score < best) { + best = score; + best_i = i; + } + } + i__ = best_i; + #ifdef NOISY_PIP { using namespace IO_Operators;