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https://gitlab.com/libeigen/eigen.git
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3cd2a125b2
- make vectors use a separate loop unroller, so that copying a row-vector into a col-vector is now possible - add much more documentation - misc improvements
24 lines
666 B
C++
24 lines
666 B
C++
#include <Eigen/Core.h>
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USING_PART_OF_NAMESPACE_EIGEN
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using namespace std;
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template<typename Scalar, typename Derived>
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Eigen::Block<Derived, 2, 2>
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topLeft2x2Corner(MatrixBase<Scalar, Derived>& m)
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{
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return Eigen::Block<Derived, 2, 2>(m.ref(), 0, 0);
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// note: tempting as it is, writing "m.block<2,2>(0,0)" here
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// causes a compile error with g++ 4.2, apparently due to
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// g++ getting confused by the many template types and
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// template arguments involved.
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}
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int main(int, char**)
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{
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Matrix3d m = Matrix3d::identity();
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cout << topLeft2x2Corner(m) << endl;
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topLeft2x2Corner(m) *= 2;
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cout << "Now the matrix m is:" << endl << m << endl;
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return 0;
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}
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