1*bf2c3715SXin Linamespace Eigen { 2*bf2c3715SXin Li 3*bf2c3715SXin Li/** \page TopicCustomizing_Plugins Extending MatrixBase (and other classes) 4*bf2c3715SXin Li 5*bf2c3715SXin LiIn this section we will see how to add custom methods to MatrixBase. Since all expressions and matrix types inherit MatrixBase, adding a method to MatrixBase make it immediately available to all expressions ! A typical use case is, for instance, to make Eigen compatible with another API. 6*bf2c3715SXin Li 7*bf2c3715SXin LiYou certainly know that in C++ it is not possible to add methods to an existing class. So how that's possible ? Here the trick is to include in the declaration of MatrixBase a file defined by the preprocessor token \c EIGEN_MATRIXBASE_PLUGIN: 8*bf2c3715SXin Li\code 9*bf2c3715SXin Liclass MatrixBase { 10*bf2c3715SXin Li // ... 11*bf2c3715SXin Li #ifdef EIGEN_MATRIXBASE_PLUGIN 12*bf2c3715SXin Li #include EIGEN_MATRIXBASE_PLUGIN 13*bf2c3715SXin Li #endif 14*bf2c3715SXin Li}; 15*bf2c3715SXin Li\endcode 16*bf2c3715SXin LiTherefore to extend MatrixBase with your own methods you just have to create a file with your method declaration and define EIGEN_MATRIXBASE_PLUGIN before you include any Eigen's header file. 17*bf2c3715SXin Li 18*bf2c3715SXin LiYou can extend many of the other classes used in Eigen by defining similarly named preprocessor symbols. For instance, define \c EIGEN_ARRAYBASE_PLUGIN if you want to extend the ArrayBase class. A full list of classes that can be extended in this way and the corresponding preprocessor symbols can be found on our page \ref TopicPreprocessorDirectives. 19*bf2c3715SXin Li 20*bf2c3715SXin LiHere is an example of an extension file for adding methods to MatrixBase: \n 21*bf2c3715SXin Li\b MatrixBaseAddons.h 22*bf2c3715SXin Li\code 23*bf2c3715SXin Liinline Scalar at(uint i, uint j) const { return this->operator()(i,j); } 24*bf2c3715SXin Liinline Scalar& at(uint i, uint j) { return this->operator()(i,j); } 25*bf2c3715SXin Liinline Scalar at(uint i) const { return this->operator[](i); } 26*bf2c3715SXin Liinline Scalar& at(uint i) { return this->operator[](i); } 27*bf2c3715SXin Li 28*bf2c3715SXin Liinline RealScalar squaredLength() const { return squaredNorm(); } 29*bf2c3715SXin Liinline RealScalar length() const { return norm(); } 30*bf2c3715SXin Liinline RealScalar invLength(void) const { return fast_inv_sqrt(squaredNorm()); } 31*bf2c3715SXin Li 32*bf2c3715SXin Litemplate<typename OtherDerived> 33*bf2c3715SXin Liinline Scalar squaredDistanceTo(const MatrixBase<OtherDerived>& other) const 34*bf2c3715SXin Li{ return (derived() - other.derived()).squaredNorm(); } 35*bf2c3715SXin Li 36*bf2c3715SXin Litemplate<typename OtherDerived> 37*bf2c3715SXin Liinline RealScalar distanceTo(const MatrixBase<OtherDerived>& other) const 38*bf2c3715SXin Li{ return internal::sqrt(derived().squaredDistanceTo(other)); } 39*bf2c3715SXin Li 40*bf2c3715SXin Liinline void scaleTo(RealScalar l) { RealScalar vl = norm(); if (vl>1e-9) derived() *= (l/vl); } 41*bf2c3715SXin Li 42*bf2c3715SXin Liinline Transpose<Derived> transposed() {return this->transpose();} 43*bf2c3715SXin Liinline const Transpose<Derived> transposed() const {return this->transpose();} 44*bf2c3715SXin Li 45*bf2c3715SXin Liinline uint minComponentId(void) const { int i; this->minCoeff(&i); return i; } 46*bf2c3715SXin Liinline uint maxComponentId(void) const { int i; this->maxCoeff(&i); return i; } 47*bf2c3715SXin Li 48*bf2c3715SXin Litemplate<typename OtherDerived> 49*bf2c3715SXin Livoid makeFloor(const MatrixBase<OtherDerived>& other) { derived() = derived().cwiseMin(other.derived()); } 50*bf2c3715SXin Litemplate<typename OtherDerived> 51*bf2c3715SXin Livoid makeCeil(const MatrixBase<OtherDerived>& other) { derived() = derived().cwiseMax(other.derived()); } 52*bf2c3715SXin Li 53*bf2c3715SXin Liconst CwiseBinaryOp<internal::scalar_sum_op<Scalar>, const Derived, const ConstantReturnType> 54*bf2c3715SXin Lioperator+(const Scalar& scalar) const 55*bf2c3715SXin Li{ return CwiseBinaryOp<internal::scalar_sum_op<Scalar>, const Derived, const ConstantReturnType>(derived(), Constant(rows(),cols(),scalar)); } 56*bf2c3715SXin Li 57*bf2c3715SXin Lifriend const CwiseBinaryOp<internal::scalar_sum_op<Scalar>, const ConstantReturnType, Derived> 58*bf2c3715SXin Lioperator+(const Scalar& scalar, const MatrixBase<Derived>& mat) 59*bf2c3715SXin Li{ return CwiseBinaryOp<internal::scalar_sum_op<Scalar>, const ConstantReturnType, Derived>(Constant(rows(),cols(),scalar), mat.derived()); } 60*bf2c3715SXin Li\endcode 61*bf2c3715SXin Li 62*bf2c3715SXin LiThen one can the following declaration in the config.h or whatever prerequisites header file of his project: 63*bf2c3715SXin Li\code 64*bf2c3715SXin Li#define EIGEN_MATRIXBASE_PLUGIN "MatrixBaseAddons.h" 65*bf2c3715SXin Li\endcode 66*bf2c3715SXin Li 67*bf2c3715SXin Li*/ 68*bf2c3715SXin Li 69*bf2c3715SXin Li} 70