eigen Questions

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I have the following test program using eigen: #include <iostream> #include <Eigen/Dense> using namespace std; using Eigen::MatrixXd; int main() { MatrixXd m(2, 2); m(0, 0) = 3; m...
Tremolo asked 24/2, 2014 at 10:25

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I'm studying simple multiplication of two big matrices using the Eigen library. This multiplication appears to be noticeably slower than both Matlab and Python for the same size matrices. Is ther...
Rumor asked 8/2, 2013 at 23:47

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I have a do_magic method which takes a double and adds 42 to it. I'd like to apply this method to each coefficient of a Eigen::Matrix or Eigen::Array (that means, I wouldn't mind if it's only possi...
Concertina asked 12/2, 2014 at 12:43

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I am having some trouble figuring out how to set the rows and columns of a MatrixXd at runtime in Eigen. Can anyone point me to some documentation or give some pointer on how to do this? Thanks.
Transpierce asked 6/11, 2013 at 19:33

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Eigen has introduced the Ref<> class to write functions with Eigen objects as parameters without the use unnecessary temporaries, when writing template functions is not wanted. One can read abou...
Millburn asked 15/1, 2014 at 8:36

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I am looking at taking the inverse of a large matrix, common size of 1000 x 1000, but sometimes exceeds 100000 x 100000 (which is currently failing due to time and memory). I know that the normal s...

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I have 2 vectors and a matrix: VectorXd A; VectorXd B; MatrixXd C; How should I efficiently (without explicit loops and working fast) compute matrix C values so that C(i,k) = A(i) * B(k)...
Mammillate asked 11/12, 2013 at 9:6

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Here is my example code: (Please note the section surrounded by #if ENABLE_MY_COMPILE_ERROR) #include <Eigen/Core> #include <iostream> #define ENABLE_MY_COMPILE_ERROR 1 void f1(cons...
Polio asked 11/12, 2013 at 1:14

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How translation a matrix(4x4) in Eigen? //identity matrix 4x4 /*type=*/Eigen::Matrix<float, 4, 4> /*name=*/result = Eigen::Matrix<float, 4, 4>::Identity(); //translation vector // 3.0...
Broadcast asked 2/12, 2013 at 8:8

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I have an (n x n) symmetric matrix A and a (n x 1) vector B. Basically, I just need to solve Ax = b for x. The issue is that A is going to potentially be massive. So I'm looking for the most effici...
Choriamb asked 24/11, 2013 at 22:30

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I am trying to slerp between 2 quaternions using Eigen(thought would be the easiest). I found two different examples One, for(int i = 0; i < list.size(); i++) { Matrix3f m; Quaternion<fl...
Pricket asked 20/10, 2013 at 10:13

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A couple of weeks ago I asked a question about the performance of matrix multiplication. I was told that in order to enhance the performance of my program I should use some specialised matrix clas...
Parchment asked 31/5, 2011 at 21:5

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I found that Eigen's Matrix is default column-major, which is like MATLAB, but how do I initialize an Eigen::MatrixXd from an cv::Mat? The following code is my test. But none of them could be compi...
Shush asked 1/10, 2013 at 11:53

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I'm trying to implement hamming error correcting codes, and to do this I need to take a bool Vector (the data) and multiply it with a bool Matrix(hamming generator matrix), performing XOR operation...
Presnell asked 16/9, 2013 at 23:23

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This should hopefully be pretty simple but i cannot find a way to do it in the Eigen documentation. Say i have a 2D vector, ie std::vector<std::vector<double> > data Assume it is f...
Breaking asked 16/9, 2013 at 23:56

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I have several transformations in Eigen, in the form of translations (Eigen::Vector3f) and rotations (Eigen::Quaternionf). I would like to combine all these transformations, in an order of my choos...
Holy asked 13/9, 2013 at 12:7

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I started a similar question on another thread, but then I was focusing on how to use OpenCV. Having failed to achieve what I originally wanted, I will ask here exactly what I want. I have two mat...
Necromancy asked 26/9, 2012 at 8:16

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I am building a sparse linear system with multiple (soft) constraints. I am converting some code which used to build the matrix with boost::ublas, to Eigen. The boost:ublas has a convenient way to ...
Emanuele asked 9/8, 2013 at 19:13

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I'd like to use Boost.Proto to transform an embedded domain-specific language into a series of matrix operations implemented with the Eigen library. Since efficiency is important, I want proto to g...
Remember asked 19/7, 2013 at 20:32

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I want to map an array of double to an existing MatrixXd structure. So far I've managed to map the Eigen matrix to a simple array, but I can't find the way to do it back. void foo(MatrixXd matrix,...
Sig asked 17/8, 2012 at 10:2

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Could someone please tell me how on earth I can iterate an Eigen::RowVectorXf? I have looked for 3 hours through the web and documentation, and all I could find is from this link that I can access...
Chatwin asked 29/5, 2013 at 22:28

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I have four column vectors. I need to append them to make a four by four matrix. Is there a constructor or something for that?
Armindaarming asked 9/5, 2013 at 20:51

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I want to move(or swap) an array of type Eigen::ArrayXXd to Eigen::MatrixXd. To achieve this, I tried, #include <iostream> #include <Eigen/Dense> using namespace std; int main(int , ch...
Footpace asked 7/5, 2013 at 6:27

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I have a buffer containing N 3D points stored as [XYZXYZXYZ ... XYZ]. This buffer can be directly mapped to a Eigen::Matrix<float, 3, N> using Eigen::Map. Since I will transform the points u...
Lytton asked 29/4, 2013 at 13:42

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I have an affine transform in 3D and I wish to discard any z-axis information from. Is there a convenient way to convert from an Affine3d to and Affine2d?
Bowl asked 23/4, 2013 at 12:50

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