[gambit-list] ffi double constants

Álvaro Castro-Castilla alvaro.castro.castilla at gmail.com
Mon Feb 20 10:56:13 EST 2012


I was using (* 2 (angle -inf.0))

But anyway, the problem is elsewhere, precision is double.

Thanks!



2012/2/20 Bradley Lucier <lucier at math.purdue.edu>:
>
> On Feb 20, 2012, at 6:42 AM, Álvaro Castro-Castilla wrote:
>
>>
>> Hi,
>>
>> I want to use the M_PI constant, which is defined in C as #define M_PI
>> 3.14159265358979323846, with 21 decimals. For the Cairo bindings, the
>> full precision is needed, because drawing a circle is done by drawing
>> an arc 2*M_PI long, and the algorithm only considers it a circle when
>> the 2*pi is passed with the proper precision.
>
> (* 8 (atan 1)) should give you 2*M_PI to 64-bit double precision, so this should work unless you're working with 80-bit long doubles.
>
>> What's the way to support this precision for the FFI bindings, so I
>> can pass that value to the affected functions as it is done in C
>> without a special wrapper function for each case?
>>
>> Best regards,
>>
>> Álvaro
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>



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