Le 28/04/2012 01:24, Jussi Lahtinen a écrit :
> At least the problem is unrelated to sin and cos...
>
> ? format(0.47942553860420300027 ^ 2 -
> 0.22984884706593014129,"#.######################")
> - .0000000000000012212453
>
> ? format(0.47942553860420300027 ^ 2.0 - 0.22984884706593014129
> ,"#.######################")
> - .0000000000000011379786
>
>
> Jussi
>
>
Hi,
OK, I found the bug.
The gambas floating point parser incorrectly took into account the
leading zero decimal digits.
In other words 2.0 was computed as 20 * 10 ^ -1, 2.00 as 200 * 10 ^ -2.
Now it is just 2.
Consequently, now 2.0 - 2 = 0, and cos(0.5) ^ 2.0 - cos(0.5) ^ 2 = 0.
But cos(0.5) ^ 2 + sin(0.5) ^ 2 keeps being not exactly 1.0. Because the
gambas algorithm is not the same as the libc algorithm. In gambas 0.5 is
computed as 5 * 10 ^ -1, which does not give the exact binary
representation of 2 ^ -1.
I will investigate...
--
Benoît Minisini
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