I’m using Eigen, trying to minimize memory allocations and would like to do something like this: Eigen::SparseMatrix A(…); A.setFromTriplets(…); Eigen::MatrixXd X = <here some data>; Eigen::SparseLU<Eigen::SparseMatrix<double>> solver; solver.compute(A); // here comes the crucial thing I want to do: X = solver.solve(X); The documentation doesn’t say much about it. I’ve tested it with many matrices A ..
Category : aliasing
I was working on highly "vectorizable" code and noted that regarding the C++ __restrict keyword/extension ~, Clang’s behavior is different and impractical compared to GCC even in a simple case. For compiler generated code, the slowdown is about 15x (in my specific case, not the exemple below). Here is the code (also available at https://godbolt.org/z/sdGd43x75): ..
Suppose I’ve written a header named foo.h, and that foo.h is also the name of one of the headers under /usr/include. Now, in my source files, I want to say #include <foo.h>, but arrange my build so that the compiler will search the directory with my foo.h before /usr/include. It is almost important that users ..
Suppose I’ve written a header named foo.h, and that foo.h is also the name of one of the headers under /usr/include. Now, in my source files, I want to say #include <foo.h>, but arrange my build so that the compiler will search the directory with my foo.h before /usr/include. Note: I realize this is a ..
Coming from a long (~20ys) abstinence in C++, it seems I’m having problems with trivialities. Given the code: template<typename T, std::size_t DIM> void add(std::array<T, DIM> &tgt, std::array<T, DIM> a, std::array<T, DIM> b) { for (int i = 0; i < DIM; i++) { tgt[i] = a[i] + b[i]; } } which should do a vector ..
I am puzzled with the following 2 simple snippets: #include <vector> struct A{ int foo(int i) const {return v[i];} std::vector<int> v; }; int f(const A &a, int i) { int j; j=a.foo(i); j=a.foo(i); return j; } which gives the assembly code: movsxd rax, esi mov rcx, qword ptr [rdi] mov eax, dword ptr [rcx + ..
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