Of course 64 and 32 bit are the sizes, not the platform! That may not be
clear.
On 5/24/2017 9:35 AM, Thaddy de Koning wrote:
Jonas, sorry for the late response:
The implementation is _*not *_undefined for negative values,_unless
you say that you define it as undefined_.
Because you seem to have implemented it or most of it.
It renders a mathematical comparable distribution in the negative to
the positive values.
In both Turbo Pascal as in Delphi and because they use a different
algorithm and made an implementation error as well, the negative
values are indeed not defined. But that's because of the algorithm and
because of the implementation by Borland (yes, it stems from Borland
times).
The Mersenne Twister we use is also valid for negative values and if
you want I can send you the mathematical proof.
I already made the LCG in Delphi compatible mode available on the wiki
and that implementation differs in so far as that it corrects the
"undefined for negative values" for that algorithm too. It is 100%
compatible for the Delphi documented range, btw.
I am busy evaluating important Random implementions for different
languages, so an FPC library is available for data that is generated
in a different language and relies on a particular PRNG.
Also note that the output of the current random is strictly valid for
32 bit only.
In my code I already added a 64 bit version.
Regards,
Thaddy
On 5/20/2017 2:57 PM, Jonas Maebe wrote:
On 20/05/17 14:36, Martin Schreiber wrote:
Is this intended? If not, which one is correct?
random(x) is undefined for negative parameters. It should have had an
unsigned parameter, like in Turbo Pascal (where it is word). Delphi
defines it as always returning a positive value, but I don't know
what happens if you pass a negative parameter there.
Jonas
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