# Memory bandwidth test code for M1 and PC **URL:** \ **Category:** Uncategorized\ **Created:** [April 8, 2022, 8:40am UTC](https://fortran-lang.discourse.group/t/memory-bandwidth-test-code-for-m1-and-pc/3184 "2022-04-08T08:40:06Z")\ **Posts on this page:** 1\ **Showing post:** 11
**Author:** ![CRquantum](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/crquantum/32/730_2.png) [@CRquantum](https://fortran-lang.discourse.group/u/CRquantum)\ **Post date:** [April 10, 2022, 3:03pm UTC](https://fortran-lang.discourse.group/t/memory-bandwidth-test-code-for-m1-and-pc/3184/11 "2022-04-10T15:03:13Z")
> [@mecej4](#): > > I was also curious as to why you chose 9 as the second argument. The returned value from the intrinsic function would have been the same if you had specified any higher value up to 307 for X86/X64 platforms. Thank you very much @mecej4 , @JohnCampbell for pointing out that. Eh, is there drawback of using `selected_real_kind(15,9)`? Or using `selected_real_kind(15)` is better than `selected_real_kind(15,9)`? I am not Fortran language lawyer, lol, but there should be a reason for `SELECTED_REAL_KIND([P, R, RADIX])` having three arugments P, R, and RADIX. Otherwise perhaps just one argument P should be enough. We could discuss here, > [@What are the true portable or best to define real 4 real 8 integer 4 integer 8, etc?](https://fortran-lang.discourse.group/t/what-are-the-true-portable-or-best-to-define-real-4-real-8-integer-4-integer-8-etc/3197/6): > > Depending on the options chosen, that file could be module stdlib\_kinds use iso\_fortran\_env, only: int8, int16, int32, int64 use iso\_c\_binding, only: c\_bool implicit none private public :: sp, dp, xdp, qp, int8, int16, int32, int64, lk, c\_bool !\> Single precision real numbers integer, parameter :: sp = selected\_real\_kind(6) !\> Double precision real numbers integer, parameter :: dp = selected\_real\_kind(15) !\> Extended double precision real numbers integer, parameter :: … --- _[View the full topic](https://fortran-lang.discourse.group/t/memory-bandwidth-test-code-for-m1-and-pc/3184)._