固定大小特征值作为参数 [英] Fixed Sized Eigen types as parameters
问题描述
我正在尝试编写一个采用固定大小本征类型的函数(但以标量类型为模板,例如float / double)。我已阅读 http://eigen.tuxfamily.org/dox/TopicFunctionTakingEigenTypes.html 但我无法使其完美运行。
这是函数定义:
template< typename T> ;
内联矩阵< T,3,3> makeSkewSymmetric(const Matrix< T,3,1& v))
{
Matrix< T,3,3>出
out<< 0,-v [2],v [1],
v [2],0,-v [0],
-v [1],v [0],0;
退回;
}
现在我正在使用以下方式:
Vector3d a(1,2,3);
Matrix3d ass = makeSkewSymmetric(a); //编译
Matrix3d ass = makeSkewSymmetric(a + a); //不编译
我想,我需要使用某种 MatrixBase< Derived>
,但是如何限制大小,因为该函数仅对长度为3的向量有意义。
编辑:我重新定义了以下函数。可以,但是有更好的方法吗?
template< typename Derived>
内联矩阵< typename Derived :: Scalar,3,3> makeSkewSymmetric(const MatrixBase< Derived& v)
{
BOOST_STATIC_ASSERT(Derived :: RowsAtCompileTime == 3&& Derived :: ColsAtCompileTime == 1);
Matrix< typename Derived :: Scalar,3,3>出
out<< 0,-v [2],v [1],
v [2],0,-v [0],
-v [1],v [0],0;
退回;
}
我只是想过一个好检查Eigen开发人员希望您解决此问题的方式的方法。 Eigen在 MatrixBase
上带有 cross
函数,但是此函数(如您的函数)仅对3D矢量有意义-因此我从Eigen3来源中挖了相关部分:(cf Eigen / src / Geometry / OrthoMethods.h
)
...
内联类型名称MatrixBase< Derived> :: template cross_product_return_type< OtherDerived> :: type
MatrixBase< Derived> :: cross(const MatrixBase< OtherDerived> & other)const
{
EIGEN_STATIC_ASSERT_VECTOR_SPECIFIC_SIZE(Derived,3)
EIGEN_STATIC_ASSERT_VECTOR_SPECIFIC_SIZE(OtherDerived,3)
...
实际上,Eigen本身使用asserts(尽管具有自己的风格)来检查广义函数中的维。
I am trying to write a function that takes fixed size Eigen Types (but templated on Scalar type e.g. float/double). I have read http://eigen.tuxfamily.org/dox/TopicFunctionTakingEigenTypes.html but I am not able to make it work perfectly.
Here is the function definition:
template <typename T> inline Matrix<T, 3, 3> makeSkewSymmetric(const Matrix<T, 3, 1>& v) { Matrix<T, 3, 3> out; out << 0, -v[2], v[1], v[2], 0, -v[0], -v[1], v[0], 0; return out; }
Now I am using this as following:
Vector3d a(1,2,3); Matrix3d ass = makeSkewSymmetric(a); // Compiles Matrix3d ass = makeSkewSymmetric(a + a); // does NOT compile
I guess, I need to use some sort of
MatrixBase<Derived>
, but then how do I restrict the size, as the function only makes sense for vectors of length 3.
Edit: I redefined the function as following. It works, but is there a better way?
template <typename Derived> inline Matrix<typename Derived::Scalar, 3, 3> makeSkewSymmetric(const MatrixBase<Derived>& v) { BOOST_STATIC_ASSERT(Derived::RowsAtCompileTime == 3 && Derived::ColsAtCompileTime == 1); Matrix<typename Derived::Scalar, 3, 3> out; out << 0, -v[2], v[1], v[2], 0, -v[0], -v[1], v[0], 0; return out; }
解决方案I just thought of a good way of checking the way the Eigen developers would want you to solve this problem. Eigen comes with a
cross
function onMatrixBase
, but this function, like yours, is only sensible for 3D vectors - so I dug up the relevant part from the Eigen3 source: (cfEigen/src/Geometry/OrthoMethods.h
)... inline typename MatrixBase<Derived>::template cross_product_return_type<OtherDerived>::type MatrixBase<Derived>::cross(const MatrixBase<OtherDerived>& other) const { EIGEN_STATIC_ASSERT_VECTOR_SPECIFIC_SIZE(Derived,3) EIGEN_STATIC_ASSERT_VECTOR_SPECIFIC_SIZE(OtherDerived,3) ...
and indeed, Eigen itself uses asserts (albeit its own flavor) to check for dimensions in generalized functions.
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