[Numpy-discussion] float128 / longdouble on PPC - is it broken?

Matthew Brett matthew.brett@gmail....
Tue Oct 25 12:45:02 CDT 2011


Hi,

On Tue, Oct 25, 2011 at 2:43 AM, Pauli Virtanen <pav@iki.fi> wrote:
> 25.10.2011 06:59, Matthew Brett kirjoitti:
>> res = np.longdouble(2)**64
>> res-1
>> 36893488147419103231.0
>
> Can you check if long double works properly (not a given) in C on that
> platform:
>
>        long double x;
>        x = powl(2, 64);
>        x -= 1;
>        printf("%g %Lg\n", (double)x, x);
>
> or, in case the platform doesn't have powl:
>
>        long double x;
>        x = pow(2, 64);
>        x -= 1;
>        printf("%g %Lg\n", (double)x, x);

Both the same as numpy:

[mb312@jerry ~]$ gcc test.c
test.c: In function 'main':
test.c:5: warning: incompatible implicit declaration of built-in function 'powl'
[mb312@jerry ~]$ ./a.out
1.84467e+19 3.68935e+19

Thanks,

Matthew


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