// Assemble lower-triangular matrix from log-diagonal and lower triangle and multiply by vector v
// [ exp(q0) 0 0 0 ]
// [ l0 exp(q2) 0 0 ]
// [ l1 l2 exp(q3) 0 ]
// [ l3 l4 l5 exp(q4) ]
VectorD Qtimesv(VectorD const& q, Vector const& l, VectorD const& v)
{
VectorD ret(v.size());
for (size_t i = 0; i < size_t(v.size()); ++i) {
// let li = vectorSlice (Card i) (tri(i - 1)) l
// let vi = vectorSlice (Card i) 0 v
// vectorSum (li.*vi) + exp(q[i])*v[i]
size_t lstart = tri(i - 1);
double out = exp(q[i]) * v[i];
for (size_t k = 0; k < i; ++k)
out += l[lstart + k] * v[k];
ret[i] = out;
}
return ret;
}
VectorD SparseMatrix::multiply_vector(VectorD& v)
{
VectorD res(v.size(), 0.0);
for(map<pair<int, int>, double>::iterator it = values.begin(); it != values.end(); it++)
{
int row = it->first.first;
int col = it->first.second;
double val = it->second;
res[row] += val*v[col];
}
return res;
}