Function value

dependence/eigen-3.4.0/Eigen/src/SparseCore/SparseBlock.h:527–527

  inline Index col()    const { return XprIsRowMajor ? index() : 0; }

  inline Scalar value() const { return m_it.value(); }
  inline Scalar& valueRef() { return m_it.valueRef(); }

  inline OuterVectorInnerIterator& operator++()