lkml.org 
[lkml]   [2014]   [Jan]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH 1/2] lib/lcm.c: Ensure correct result whenever it fits
Date
Rasmus Villemoes <linux@rasmusvillemoes.dk> writes:

Ping...

> Ensure that lcm(a,b) returns the mathematically correct result,
> provided it fits in an unsigned long. The current version returns
> garbage if a*b overflows, even if the final result would fit.
>
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
> There are of course still plenty of cases where the return value is
> wrong.
>
> lib/lcm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/lcm.c b/lib/lcm.c
> index b9c8de4..01b3aa9 100644
> --- a/lib/lcm.c
> +++ b/lib/lcm.c
> @@ -7,7 +7,7 @@
> unsigned long lcm(unsigned long a, unsigned long b)
> {
> if (a && b)
> - return (a * b) / gcd(a, b);
> + return (a / gcd(a, b)) * b;
> else if (b)
> return b;



\
 
 \ /
  Last update: 2014-01-14 13:21    [W:0.039 / U:0.276 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site