![]() Smellsofbikes on Pieca Is A Pi Camera With Some Very Nice Lenses.Jonathan Wilson on Hackaday Links: November 6, 2022.smellsofbikes on Say No To Obsolescence, Wire Up Your House With Fiber.Stuart Longland on M.2 For Hackers – Cards.Chr e on Recycled Chairs Bring The Subway To Your Living Room.Make Your Pi Moonlight As A Security Camera 21 Comments If you’re looking for a powerful open-source calculator, this BeagleBoard-based machine runs the R statistical computing environment.Ĭontinue reading “2022 Cyberdeck Contest: The Galdeano Is More Than A Graphing Calculator” → Posted in handhelds hacks Tagged Eigenmath, ESP32, graphing calculator, micropython Of course, even classroom-grade calculators can be pushed to do much more than their designers intended: they can receive GPS signals, run Debian or even perform ray tracing. ![]() ![]() Arya Voronova on M.2 For Hackers – Cards.AlphaWorm on Pieca Is A Pi Camera With Some Very Nice Lenses.smellsofbikes on Garage Door Opener Ejection Seat.Dave Henry has updated the project titled Nanocomp 6809 8 Bit Retro Computer on Breadboards.Richard Hogben has added EVA to Just Cubes.adriancubas wrote a reply on 3D PRINTED PORTABLE WIND TURBINE.The Eigen header files define many types, but for simple applications it may be enough to use only the MatrixXd type. This represents a matrix of arbitrary size (hence the X in MatrixXd), in which every entry is a double (hence the d in MatrixXd). See the quick reference guide for an overview of the different types you can use to represent a matrix. The Eigen/Dense header file defines all member functions for the MatrixXd type and related types (see also the table of header files). All classes and functions defined in this header file (and other Eigen header files) are in the Eigen namespace. The first line of the main function declares a variable of type MatrixXd and specifies that it is a matrix with 2 rows and 2 columns (the entries are not initialized). The statement m(0,0) = 3 sets the entry in the top-left corner to 3. You need to use round parentheses to refer to entries in the matrix. As usual in computer science, the index of the first index is 0, as opposed to the convention in mathematics that the first index is 1. The following three statements sets the other three entries. The final line outputs the matrix m to the standard output stream. Here is another example, which combines matrices with vectors. Concentrate on the left-hand program for now we will talk about the right-hand program later. The second example starts by declaring a 3-by-3 matrix m which is initialized using the Random() method with random values between -1 and 1. The next line applies a linear mapping such that the values are between 10 and 110. The function call MatrixXd::Constant(3,3,1.2) returns a 3-by-3 matrix expression having all coefficients equal to 1.2. The next line of the main function introduces a new type: VectorXd. This represents a (column) vector of arbitrary size. The one but last line uses the so-called comma-initializer, explained in Advanced initialization, to set all coefficients of the vector v to be as follows: Here, the vector v is created to contain 3 coefficients which are left uninitialized. The final line of the program multiplies the matrix m with the vector v and outputs the result. Now look back at the second example program. In the version in the left column, the matrix is of type MatrixXd which represents matrices of arbitrary size. The version in the right column is similar, except that the matrix is of type Matrix3d, which represents matrices of a fixed size (here 3-by-3). Because the type already encodes the size of the matrix, it is not necessary to specify the size in the constructor compare MatrixXd m(3,3) with Matrix3d m. Similarly, we have VectorXd on the left (arbitrary size) versus Vector3d on the right (fixed size). Note that here the coefficients of vector v are directly set in the constructor, though the same syntax of the left example could be used too. The use of fixed-size matrices and vectors has two advantages. ![]() ![]() The compiler emits better (faster) code because it knows the size of the matrices and vectors. Specifying the size in the type also allows for more rigorous checking at compile-time. ![]()
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