Dense(int rows, int cols, int block_size):m(rows,cols),r(rows),v(rows)
{
for(int i = 0 ; i < rows/block_size ; ++i)
m.block(i*block_size,i*block_size,block_size,block_size) = Eigen::MatrixXd::Random(block_size,block_size);
v = v.Random(rows);
}
