I think it’s likely that the fastest performance will be achieved by using the CUBLAS batch gemm function which was specifically designed for this purpose (performing a large number of “relatively small” matrix-matrix multiply operations). Even though you want to multiply your array of matrices (M[]) by a single matrix (N), the batch gemm function … Read more
why doesn’t reinterpret_cast handle that for me? One reason is that the size, alignment, and bit representations aren’t specified, so such a conversion wouldn’t be portable. However, that wouldn’t really justify making the behaviour undefined, just implementation-defined. By making it undefined, the compiler is allowed to assume that expressions of unrelated types don’t access the … Read more
Compile with gcc -masm=intel and don’t try to switch modes inside the asm template string. AFAIK there’s no equivalent before clang14 (Note: MacOS installs clang as gcc / g++ by default.) Also, of course you need to use valid GNU C inline asm, using operands to tell the compiler which C objects you want to … Read more
Try: std::cout << std::numeric_limits<int>::max() << std::endl; // requires you to #include <limits> int on your system is likely a 32-bit signed two’s complement number, which means the max value it can represent is 2,147,483,647. Your number, 3,999,999,999, is larger than that, and can’t be properly represented by int. cin fails, alerting you of the problem. … Read more
You can create a macro like #define FUNCTORIZE(func) [](auto&&… val) \ noexcept(noexcept(func(std::forward<decltype(val)>(val)…))) -> decltype(auto) \ {return func(std::forward<decltype(val)>(val)…);} which will let you wrap any callable into a closure object. You would use it like auto constexpr predObj = FUNCTORIZE(pred);
Important: see update at the end for POSIX systems. My opinion is that you should use the APIs/syscalls provided by the various platforms you wish to support, or use some kind of abstraction layer (the Boost.Process library, mentioned by Noah Roberts, may be an idea) to avoid dealing with platform-specific details. I strongly disagree with … Read more
Any type can be used as a key as long as it is Copyable Assignable Comparable, since the map is sorted by key If your class is just a simple structure, then it’s already copyable and assignable. For a class to be comparable, you must either implement operator<, or create the map with a custom … Read more
FIRST- use difftime to compare: you can simply use difftime() function to compare time and return 1 or -1 as follows: int comparetime(time_t time1,time_t time2){ return difftime(time1,time2) > 0.0 ? 1 : -1; } SECOND- Convert string into time: If you have difficulty to convert string into time_t struct, you can use two functions in … Read more
The expression p++ which you’ve written is at namespace scope. It is forbidden by the grammer of namespace-body which is defined in §7.3.1/1 as: namespace-body: declaration-seqopt which says the namespace-body can optionally contain only declaration. And p++ is surely not a declaration, it is an expression, therefore the Standard implicitly forbids it. The Standard might … Read more
c++ warning: address of local variable