`(A.array() == A.array()).matrix()` 有什么问题？
What wrong with `(A.array() == A.array()).matrix()`?
这是我的代码：
MatrixXd A(3,3);
A<<1,2,3,4,5,6,7,8,9;
MatrixXd b(3,3);
b = (A.array() == A.array()).matrix();
cout<<b<<endl;
这表明 (A.array() == A.array()).matrix() 有问题。
这是错误消息：
In file included from /home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/Core:254:0,
from /home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/Dense:1,
from /home/biss/Desktop/self-driving-car/term2/kalman-Filter/cpp_normal_op/clion_c/main.cpp:2:
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/Assign.h: In instantiation of ‘Derived& Eigen::DenseBase<Derived>::lazyAssign(const Eigen::DenseBase<OtherDerived>&) [with OtherDerived = Eigen::MatrixWrapper<const Eigen::CwiseBinaryOp<Eigen::internal::scalar_cmp_op<double, (Eigen::internal::ComparisonName)0u>, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> >, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> > > >; Derived = Eigen::Matrix<double, -1, -1>]’:
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/PlainObjectBase.h:414:30: required from ‘Derived& Eigen::PlainObjectBase<Derived>::lazyAssign(const Eigen::DenseBase<OtherDerived>&) [with OtherDerived = Eigen::MatrixWrapper<const Eigen::CwiseBinaryOp<Eigen::internal::scalar_cmp_op<double, (Eigen::internal::ComparisonName)0u>, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> >, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> > > >; Derived = Eigen::Matrix<double, -1, -1>]’
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/Assign.h:527:123: required from ‘static Derived& Eigen::internal::assign_selector<Derived, OtherDerived, false, false>::run(Derived&, const OtherDerived&) [with Derived = Eigen::Matrix<double, -1, -1>; OtherDerived = Eigen::MatrixWrapper<const Eigen::CwiseBinaryOp<Eigen::internal::scalar_cmp_op<double, (Eigen::internal::ComparisonName)0u>, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> >, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> > > >]’
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/PlainObjectBase.h:653:72: required from ‘Derived& Eigen::PlainObjectBase<Derived>::_set_noalias(const Eigen::DenseBase<OtherDerived>&) [with OtherDerived = Eigen::MatrixWrapper<const Eigen::CwiseBinaryOp<Eigen::internal::scalar_cmp_op<double, (Eigen::internal::ComparisonName)0u>, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> >, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> > > >; Derived = Eigen::Matrix<double, -1, -1>]’
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/PlainObjectBase.h:638:114: required from ‘void Eigen::PlainObjectBase<Derived>::_set_selector(const OtherDerived&, const Eigen::internal::false_type&) [with OtherDerived = Eigen::MatrixWrapper<const Eigen::CwiseBinaryOp<Eigen::internal::scalar_cmp_op<double, (Eigen::internal::ComparisonName)0u>, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> >, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> > > >; Derived = Eigen::Matrix<double, -1, -1>]’
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/PlainObjectBase.h:630:20: required from ‘Derived& Eigen::PlainObjectBase<Derived>::_set(const Eigen::DenseBase<OtherDerived>&) [with OtherDerived = Eigen::MatrixWrapper<const Eigen::CwiseBinaryOp<Eigen::internal::scalar_cmp_op<double, (Eigen::internal::ComparisonName)0u>, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> >, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> > > >; Derived = Eigen::Matrix<double, -1, -1>]’
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/Matrix.h:172:24: required from ‘Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>& Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>::operator=(const Eigen::MatrixBase<OtherDerived>&) [with OtherDerived = Eigen::MatrixWrapper<const Eigen::CwiseBinaryOp<Eigen::internal::scalar_cmp_op<double, (Eigen::internal::ComparisonName)0u>, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> >, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> > > >; _Scalar = double; int _Rows = -1; int _Cols = -1; int _Options = 0; int _MaxRows = -1; int _MaxCols = -1]’
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/cpp_normal_op/clion_c/main.cpp:23:7: required from here
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/util/StaticAssert.h:32:40: error: static assertion failed: YOU_MIXED_DIFFERENT_NUMERIC_TYPES__YOU_NEED_TO_USE_THE_CAST_METHOD_OF_MATRIXBASE_TO_CAST_NUMERIC_TYPES_EXPLICITLY
#define EIGEN_STATIC_ASSERT(X,MSG) static_assert(X,#MSG);
^
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/Assign.h:500:3: note: in expansion of macro ‘EIGEN_STATIC_ASSERT’
EIGEN_STATIC_ASSERT(SameType,YOU_MIXED_DIFFERENT_NUMERIC_TYPES__YOU_NEED_TO_USE_THE_CAST_METHOD_OF_MATRIXBASE_TO_CAST_NUMERIC_TYPES_EXPLICITLY)
^
CMakeFiles/clion_c.dir/build.make:62: recipe for target 'CMakeFiles/clion_c.dir/main.cpp.o' failed
make[3]: *** [CMakeFiles/clion_c.dir/main.cpp.o] Error 1
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/clion_c.dir/all' failed
make[2]: *** [CMakeFiles/clion_c.dir/all] Error 2
CMakeFiles/Makefile2:79: recipe for target 'CMakeFiles/clion_c.dir/rule' failed
make[1]: *** [CMakeFiles/clion_c.dir/rule] Error 2
Makefile:118: recipe for target 'clion_c' failed
make: *** [clion_c] Error 2
但是，如果我更改我的代码：
MatrixXd A(3,3);
A<<1,2,3,4,5,6,7,8,9;
MatrixXd b(3,3);
b = (A.array() * A.array()).matrix();
cout<<b<<endl;
可以运行还行
1 4 9
16 25 36
49 64 81
如果我想做这个操作：(A.array() == A.array()).matrix()，我应该怎么做？
让我们分解一下。 (A.array() == A.array()) 表示具有布尔值的 (2D) 数组，显示元素相等。如果你要写
std::cout << (A.array() == A.array());
你会得到
1 1 1
1 1 1
1 1 1
正如您所问的那样，A 是否等于其自身，而它恰好没有任何 NAN。您收到的错误消息显示 error: static assertion failed: YOU_MIXED_DIFFERENT_NUMERIC_TYPES__YOU_NEED_TO_USE_THE_CAST_METHOD_OF_MATRIXBASE_TO_CAST_NUMERIC_TYPES_EXPLICITLY。这就是那个意思。您也不能将 MatrixXf 分配给 MatrixXd。没有隐式转换。所以，为了让它工作，你想写
b = (A.array() == A.array()).cast<double>().matrix();
它显式地将布尔值转换为双精度值。我很确定这不是你想要做的，但这就是你所写的问题（希望是因为它是一个不完整的 MCVE）。
这是我的代码：
MatrixXd A(3,3);
A<<1,2,3,4,5,6,7,8,9;
MatrixXd b(3,3);
b = (A.array() == A.array()).matrix();
cout<<b<<endl;
这表明 (A.array() == A.array()).matrix() 有问题。
这是错误消息：
In file included from /home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/Core:254:0,
from /home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/Dense:1,
from /home/biss/Desktop/self-driving-car/term2/kalman-Filter/cpp_normal_op/clion_c/main.cpp:2:
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/Assign.h: In instantiation of ‘Derived& Eigen::DenseBase<Derived>::lazyAssign(const Eigen::DenseBase<OtherDerived>&) [with OtherDerived = Eigen::MatrixWrapper<const Eigen::CwiseBinaryOp<Eigen::internal::scalar_cmp_op<double, (Eigen::internal::ComparisonName)0u>, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> >, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> > > >; Derived = Eigen::Matrix<double, -1, -1>]’:
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/PlainObjectBase.h:414:30: required from ‘Derived& Eigen::PlainObjectBase<Derived>::lazyAssign(const Eigen::DenseBase<OtherDerived>&) [with OtherDerived = Eigen::MatrixWrapper<const Eigen::CwiseBinaryOp<Eigen::internal::scalar_cmp_op<double, (Eigen::internal::ComparisonName)0u>, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> >, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> > > >; Derived = Eigen::Matrix<double, -1, -1>]’
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/Assign.h:527:123: required from ‘static Derived& Eigen::internal::assign_selector<Derived, OtherDerived, false, false>::run(Derived&, const OtherDerived&) [with Derived = Eigen::Matrix<double, -1, -1>; OtherDerived = Eigen::MatrixWrapper<const Eigen::CwiseBinaryOp<Eigen::internal::scalar_cmp_op<double, (Eigen::internal::ComparisonName)0u>, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> >, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> > > >]’
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/PlainObjectBase.h:653:72: required from ‘Derived& Eigen::PlainObjectBase<Derived>::_set_noalias(const Eigen::DenseBase<OtherDerived>&) [with OtherDerived = Eigen::MatrixWrapper<const Eigen::CwiseBinaryOp<Eigen::internal::scalar_cmp_op<double, (Eigen::internal::ComparisonName)0u>, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> >, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> > > >; Derived = Eigen::Matrix<double, -1, -1>]’
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/PlainObjectBase.h:638:114: required from ‘void Eigen::PlainObjectBase<Derived>::_set_selector(const OtherDerived&, const Eigen::internal::false_type&) [with OtherDerived = Eigen::MatrixWrapper<const Eigen::CwiseBinaryOp<Eigen::internal::scalar_cmp_op<double, (Eigen::internal::ComparisonName)0u>, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> >, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> > > >; Derived = Eigen::Matrix<double, -1, -1>]’
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/PlainObjectBase.h:630:20: required from ‘Derived& Eigen::PlainObjectBase<Derived>::_set(const Eigen::DenseBase<OtherDerived>&) [with OtherDerived = Eigen::MatrixWrapper<const Eigen::CwiseBinaryOp<Eigen::internal::scalar_cmp_op<double, (Eigen::internal::ComparisonName)0u>, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> >, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> > > >; Derived = Eigen::Matrix<double, -1, -1>]’
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/Matrix.h:172:24: required from ‘Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>& Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>::operator=(const Eigen::MatrixBase<OtherDerived>&) [with OtherDerived = Eigen::MatrixWrapper<const Eigen::CwiseBinaryOp<Eigen::internal::scalar_cmp_op<double, (Eigen::internal::ComparisonName)0u>, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> >, const Eigen::ArrayWrapper<Eigen::Matrix<double, -1, -1> > > >; _Scalar = double; int _Rows = -1; int _Cols = -1; int _Options = 0; int _MaxRows = -1; int _MaxCols = -1]’
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/cpp_normal_op/clion_c/main.cpp:23:7: required from here
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/util/StaticAssert.h:32:40: error: static assertion failed: YOU_MIXED_DIFFERENT_NUMERIC_TYPES__YOU_NEED_TO_USE_THE_CAST_METHOD_OF_MATRIXBASE_TO_CAST_NUMERIC_TYPES_EXPLICITLY
#define EIGEN_STATIC_ASSERT(X,MSG) static_assert(X,#MSG);
^
/home/biss/Desktop/self-driving-car/term2/kalman-Filter/Eigen/src/Core/Assign.h:500:3: note: in expansion of macro ‘EIGEN_STATIC_ASSERT’
EIGEN_STATIC_ASSERT(SameType,YOU_MIXED_DIFFERENT_NUMERIC_TYPES__YOU_NEED_TO_USE_THE_CAST_METHOD_OF_MATRIXBASE_TO_CAST_NUMERIC_TYPES_EXPLICITLY)
^
CMakeFiles/clion_c.dir/build.make:62: recipe for target 'CMakeFiles/clion_c.dir/main.cpp.o' failed
make[3]: *** [CMakeFiles/clion_c.dir/main.cpp.o] Error 1
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/clion_c.dir/all' failed
make[2]: *** [CMakeFiles/clion_c.dir/all] Error 2
CMakeFiles/Makefile2:79: recipe for target 'CMakeFiles/clion_c.dir/rule' failed
make[1]: *** [CMakeFiles/clion_c.dir/rule] Error 2
Makefile:118: recipe for target 'clion_c' failed
make: *** [clion_c] Error 2
但是，如果我更改我的代码：
MatrixXd A(3,3);
A<<1,2,3,4,5,6,7,8,9;
MatrixXd b(3,3);
b = (A.array() * A.array()).matrix();
cout<<b<<endl;
可以运行还行
1 4 9
16 25 36
49 64 81
如果我想做这个操作：(A.array() == A.array()).matrix()，我应该怎么做？
让我们分解一下。 (A.array() == A.array()) 表示具有布尔值的 (2D) 数组，显示元素相等。如果你要写
std::cout << (A.array() == A.array());
你会得到
1 1 1
1 1 1
1 1 1
正如您所问的那样，A 是否等于其自身，而它恰好没有任何 NAN。您收到的错误消息显示 error: static assertion failed: YOU_MIXED_DIFFERENT_NUMERIC_TYPES__YOU_NEED_TO_USE_THE_CAST_METHOD_OF_MATRIXBASE_TO_CAST_NUMERIC_TYPES_EXPLICITLY。这就是那个意思。您也不能将 MatrixXf 分配给 MatrixXd。没有隐式转换。所以，为了让它工作，你想写
b = (A.array() == A.array()).cast<double>().matrix();
它显式地将布尔值转换为双精度值。我很确定这不是你想要做的，但这就是你所写的问题（希望是因为它是一个不完整的 MCVE）。