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simplify scal_prod if all abs(coeeficients) are equals; gains 15% on oc-roster.mzn

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lperron@google.com
2013-09-18 17:07:01 +00:00
parent 5aac63856d
commit ae2b3d6870
1 changed files with 16 additions and 0 deletions
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16
src/constraint_solver/expr_array.cc
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@@ -2827,6 +2827,22 @@ IntExpr* MakeScalProdFct(Solver* solver, const std::vector<IntVar*>& pre_vars,
coefs.push_back(iter->second);
}
}
// Are all coefficients equal or abs equals.
int64 abs_coef = std::abs(coefs[0]);
for (int i = 1; i < coefs.size(); ++i) {
int64 new_abs_coef = std::abs(coefs[i]);
if (new_abs_coef != abs_coef) {
abs_coef = 0;
break;
}
}
if (abs_coef > 1 && constant % abs_coef == 0) {
for (int i = 0; i < coefs.size(); ++i) {
coefs[i] /= abs_coef;
}
return solver->MakeProd(
MakeScalProdAux(solver, vars, coefs, constant / abs_coef), abs_coef);
}
return MakeScalProdAux(solver, vars, coefs, constant);
}