Talk:Rare numbers: Difference between revisions
→21+ digit rare numbers: Replied to Nigel.
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::::I've entered code in C++ which I expect using clang++ on the monster beasts you have for computers will complete 21 in a day and a quarter and 22 in less than 4 days. The difference between clang++ and g++ is suprising. It would be interesting to know how MSVC does.--[[User:Nigel Galloway|Nigel Galloway]] ([[User talk:Nigel Galloway|talk]]) 12:28, 20 December 2019 (UTC)
:::::I don't have clang but, compiling your C++ code for 10 to 19 digits on my core i7 using g++ v7.4 (-std=c++17 -O3) on Ubuntu 18.04, produces execution times of 11.7, 78, 221 and 1484 seconds for rare numbers with 16, 17, 18 and 19 digits respectively. The corresponding times for the Go entry (with the Julia entry not far behind) were 221, 355, 4532 and 6610 seconds so, even if we assume these languages are 2 or 3 times slower than C++, the algorithm you're now using is considerably more efficient than what we had before.
::::: I find it hard to believe that clang++ could be 3 times faster than g++ (though you can get some strange results with these CPU-intensive tasks) and, although I no longer have an up to date Windows machine, on past form I'd be surprised if Visual C++ were any faster than g++ itself. Enter your username may be able to confirm the position there. --[[User:PureFox|PureFox]] ([[User talk:PureFox|talk]]) 20:53, 20 December 2019 (UTC)
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