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Pass std::iterator pointing to a vector of Eigen types


Pass std::iterator pointing to a vector of Eigen types

By : jhonapple69
Date : November 28 2020, 11:01 PM
it should still fix some issue In your example *v1_beg will return a reference to a Eigen::Array (which is the same as Eigen::ArrayXf, btw), no Eigen code is invoked up to that place. The actual Eigen code then calls (semi pseudo code):
code :
ArrayXf::operator+=(operator*(const ArrayXf&, const ArrayXf&))


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Does using Eigen types with boost::bind automatically violate Eigen's "only pass by reference" rule?

Does using Eigen types with boost::bind automatically violate Eigen's "only pass by reference" rule?


By : Atle Svendsen
Date : March 29 2020, 07:55 AM
hope this fix your issue boost::bind will effectively pass arguments as values. Unless you wrap them with boost::(c)ref, then it would be just the wrapper which gets passed by value.
Using Eigen types with STL containers and std::vector

Using Eigen types with STL containers and std::vector


By : Feras Assaf
Date : March 29 2020, 07:55 AM
hope this fix your issue Yes your understanding is mostly correct, but I should add that this only concerns Eigen's fixed size types that require alignment such as Vector4f, Matrix2d, etc. but not Vector3f or MatrixXd. Moreover, the core of the problem is that STL containers do not honor alignas requirements yet, though this should come in some future C++ version.
I think that the easiest way to avoid such difficulties is to use non-aligned Eigen's types for class members and container value-types such as:
code :
typedef Eigen::Matrix<float,4,1,Eigen::DontAlign> UVector4f;
typedef Eigen::Matrix<double,2,2,Eigen::DontAlign> UMatrix2d;
How to use an iterator pointing to a vector of structs c++?

How to use an iterator pointing to a vector of structs c++?


By : qeusan
Date : March 29 2020, 07:55 AM
hop of those help? std::find_if only finds the first occurence. But you could search the next element beginning at the successor of the currently found element, such as:
code :
auto vpit = buff.begin();
while(vpit != buff.end())
{
    vpit = std::find_if(vpit, buff.end(), [](/*...*/){ /*...*/ });
    if(vpit != buff.end())
    {
        // use it
        ++vpit; // for not finding current element AGAIN!
    }
}
for(auto e : buff)
{
     if( /* ... */ )
     { /* ... */ }
}
receptionEvents someCopy = *vpit; // copies entire struct
int cfIndex = vpit->chFreqIndex;
Eigen::Vector; Initialize Vector with Values of Eigen::Matrix3f in a function, bigger than 4 entries

Eigen::Vector; Initialize Vector with Values of Eigen::Matrix3f in a function, bigger than 4 entries


By : user1640303
Date : March 29 2020, 07:55 AM
hope this fix your issue For dynamically filling a big matrix at runtime you can't use the CommaInitializer (without abusing it). Just allocate a matrix large enough and set individual blocks:
code :
Matrix<float, Dynamic, 6> Vges(2*views, 6);
for(int i=0; i<views; ++i) {
    Matrix<float, 2, 6> foo;
    foo << 1,2,3,4,5,6,7,8,9,10,11,12; // or combine from two Matrix<float, 1, 6>

    Vges.middleRows<2>(2*i) = foo;
}
Eigen::Matrix<double, 6, 6> VtV; VtV.setZero();

for(int i=0; i<views; ++i) {
    foo = ...;
    VtV.selfadjointView<Upper>().rankUpdate(foo);
}
What will happen if I call a method on an iterator pointing to an empty element of a vector?

What will happen if I call a method on an iterator pointing to an empty element of a vector?


By : Reshmi Hillary
Date : March 29 2020, 07:55 AM
will help you From the documentation for std::vector::clear (http://www.cplusplus.com/reference/vector/vector/clear/):
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