21 lines
724 B
C++
21 lines
724 B
C++
#include <Eigen/Core>
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#include <iostream>
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template <typename Derived>
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Eigen::Block<Derived, 2, 2> topLeft2x2Corner(Eigen::MatrixBase<Derived>& m) {
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return Eigen::Block<Derived, 2, 2>(m.derived(), 0, 0);
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}
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template <typename Derived>
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const Eigen::Block<const Derived, 2, 2> topLeft2x2Corner(const Eigen::MatrixBase<Derived>& m) {
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return Eigen::Block<const Derived, 2, 2>(m.derived(), 0, 0);
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}
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int main(int, char**) {
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Eigen::Matrix3d m = Eigen::Matrix3d::Identity();
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std::cout << topLeft2x2Corner(4 * m) << std::endl; // calls the const version
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topLeft2x2Corner(m) *= 2; // calls the non-const version
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std::cout << "Now the matrix m is:" << std::endl << m << std::endl;
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return 0;
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}
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