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Should I then put all the members of Eigen types at the beginning of my class? The reader should be able to perform addition, multiplication, scalar multiplication, and. The solution is to let class Foo have an aligned "operator new", as we showed in the previous section. Use Eigen for basic algebraic operations on matrices and vectors.

If the foo pointer wasn't aligned, then foo->v won't be aligned either! The alignment attribute of the member v is then relative to the start of the class, foo. When you have a class Foo like above, and you dynamically allocate a new Foo as above, then, since Foo doesn't have aligned "operator new", the returned pointer foo is not necessarily 128-bit aligned. Sort pixels f x,y1 of an image into column vector of length N.

Eigen overloads the "operator new" of Eigen::Vector2d so it will always return 128-bit aligned pointers.With GCC, this is done with a _attribute_ ((aligned(16))). Eigen requires 128-bit alignment for the Eigen::Vector2d's array (of 2 doubles).Otherwise you get a segmentation fault.įor this reason, Eigen takes care by itself to require 128-bit alignment for Eigen::Vector2d, by doing two things: But SSE instructions (at least the ones that Eigen uses, which are the fast ones) require 128-bit alignment. I was initially confused because in Eigen d is double and say for matrices, when you declare a variable, you select types Matrix3f (3x3, float), Matrix2d (2x2.

rot2d(ortho2d) Eigen::Rotation2D is a templated class, so when you declare a variable it has to be with a type.

For the example above we found without any calculation the Eigenvectors. A Eigen::Vector2d consists of 2 doubles, which is 128 bits. Eigen matrices have a range of methods that reduce them to a vector or even a. The above figure shows the the transformation of a vector by mirroring on the (1.