[erlang-questions] A math module better than C89

Michael Truog <>
Fri Jan 20 01:02:58 CET 2017


On 01/19/2017 03:30 PM, Richard A. O'Keefe wrote:
>
>
> On 20/01/17 7:00 AM, Michael Truog wrote:
>
>> We do have floor/ceil now (from https://github.com/erlang/otp/pull/1145)
>> when the source code is released in Erlang/OTP 20.0 and these functions
>> are guard functions, though that means they both exist in the erlang
>> module, not the math module.
>
> That is good to hear.
>
> As a minor documentation issue, because there will be people exposed to
> C or Java who expect functions called round, trunc, floor, ceil to be
> in the same place as sqrt and acosh, it would be helpful if the
> manual page for the math module mentioned these functions, maybe at the
> end, and said where to really find them.  I'm not talking about
> repeating their descriptions, just pointing to them.

I was wrong about this a bit.  There are ceil/floor functions added to the math function that use the same logic as the erlang module ceil/floor functions.  The main difference is that the math module return type is float while the erlang module return type is integer.  So, ceil/floor are present in the math module, though the math module doc probably wants a pointer to the erlang module ceil/floor by mentioning that it returns integer instead of float.



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