Here is also a somewhat representative example of various grid initialization pay attention to version 3 where the compiler unrolls the loop in O3 its likely th

Here is also a somewhat representative example of various grid initialization pay attention to version 3 where the compiler unrolls the loop in O3 its likely the fastest version. https://godbolt.org/g/mMBhuW https://godbolt.org/g/mMBhuW