denseCancelFromSparse() [2/2]

template<typename RingType>

void ConcreteVectorArithmetic< RingType >::denseCancelFromSparse ( ElementArray & dense, const ElementArray & sparse, const Range< const int > & comps, ElementArray & result_multiplier ) const

inline

Definition at line 254 of file VectorArithmetic.hpp.

  {
    // ASSUMPTION: svec[0] == 1, comps.size() >= 1
    auto& dvec = * elementArray(dense);
    auto& svec = * elementArray(sparse);
    auto& mults = * elementArray(result_multiplier);
 
    FieldElement b;
    mRing->init(b);
    mRing->set(b, dvec[comps[0]]);
 
    FieldElement one;
    mRing->init(one);
    mRing->set_from_long(one, 1);
    if (not mRing->is_equal(svec[0], one))  // should be minus_one
      mRing->negate(b, b);
 
    for (int i=1; i < comps.size(); ++i)
      {
        mRing->subtract_multiple(dvec[comps[i]], b, svec[i]);
        mStats.incrementNumAdditions();
      }
    mRing->set_zero(dvec[comps[0]]);
 
    mRing->negate(b, b);
    mults.push_back(b); // this transfers ownership of b.
  }

References dvec(), elementArray(), mRing, mStats, and Range< T >::size().