Re: [PATCH 1/2] fmod.3: add note how to obtain modulus/LPR

[Alejandro Colomar <alx@kernel.org>]

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Hi Jan,

On 2023-07-24 15:49, Jan Engelhardt wrote:
> Signed-off-by: Jan Engelhardt <jengelh@inai.de>
> ---
>  man3/fmod.3 | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/man3/fmod.3 b/man3/fmod.3
> index ee2333fdc..a33b83eb5 100644
> --- a/man3/fmod.3
> +++ b/man3/fmod.3
> @@ -58,6 +58,9 @@ is the quotient of
>  /
>  .IR y ,
>  rounded toward zero to an integer.
> +.PP
> +To obtain the modulus, more specifically, the Least Positive Residue, the
> +expression "fmod(fmod(x, y) + y, y)" needs to be used.

There's a more readable way (and it's probably also more efficient):
<https://stackoverflow.com/a/2708900>

I think it would be interesting to have an example program that
shows both, and implements a function double lpr(double, double)
that uses the branchy implementation.

Thanks,
Alex

>  .SH RETURN VALUE
>  On success, these
>  functions return the value \fIx\fP\ \-\ \fIn\fP*\fIy\fP,

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