Hi,
When assigning a row vector into VectorXd (eg. a column vector), it does an
implicit transpose in most cases (like in the line `VectorXd tmp = m.row(i) -
m.row(j);` below).
I'm wondering why it doesn't behave the same way in line `VectorXd v3 =
(m.row(i) - m.row(j)).cwiseQuotient(q);`. This gives the the wrong result in
release mode (but calls`abort` in debug mode due to size mismatch).
Why does the assignment of `v3` behaves differently than the assignment of
`tmp` in the example below? Is this documented behavior?
Cheers,
Jean-Claude
{
using namespace Eigen;
MatrixXd m = MatrixXd::Random(10, 4);
VectorXd q = VectorXd::Random(m.cols());
Index i = 3;
Index j = 8;
VectorXd tmp = m.row(i) - m.row(j);
VectorXd v1 = tmp.cwiseQuotient(q);
VectorXd v2 = (m.row(i) - m.row(j)).transpose().cwiseQuotient(q);
VectorXd v3 = (m.row(i) - m.row(j)).cwiseQuotient(q);
std::cout << "v1 rows:" << v1.rows() << ", cols:" << v1.cols() <<
std::endl;
std::cout << "v2 rows:" << v2.rows() << ", cols:" << v2.cols() <<
std::endl;
std::cout << "v3 rows:" << v3.rows() << ", cols:" << v3.cols() <<
std::endl;
std::cout << "v1 = " << v1.transpose() << std::endl;
std::cout << "v2 = " << v2.transpose() << std::endl;
std::cout << "v3 = " << v3.transpose() << std::endl;
}
Output in release mode:
v1 rows:4, cols:1
v2 rows:4, cols:1
v3 rows:1, cols:1
v1 = -0.0375015 1.61562 -1.3097 -0.394064
v2 = -0.0375015 1.61562 -1.3097 -0.394064
v3 = -0.0375015
