32 bit or 64 bit?

ram.rachum at gmail.com ram.rachum at gmail.com
Sun Jun 15 21:10:16 CEST 2008


On Jun 15, 8:52 pm, Peter Otten <__pete... at web.de> wrote:
> ram.rac... at gmail.com wrote:
> > I have a physical system set up in which a body is supposed to
> > accelerate and to get very close to lightspeed, while never really
> > attaining it. After approx. 680 seconds, Python gets stuck and tells
> > me the object has passed lightspeed. I put the same equations in
> > Mathematica, again I get the same mistake around 680 seconds. So I
> > think, I have a problem with my model! Then I pump up the
> > WorkingPrecision in Mathematica to about 10. I run the same equations
> > again, and it works! At least for the first 10,000 seconds, the object
> > does not pass lightspeed.
>
> That the values are possible doesn't mean that you can trust them.
>

I do not understand this comment.

> > I concluded that I need Python to work at a higher precision.
>
> How is WorkingPrecision defined? Python floats have about 16 significant
> digits in base 10, so at first glance I would guess that you switched to
> a /lower/ precision.
>

I don't know how WorkingPrecision is defined. However, I think it's
not lower, it's higher.

> But I've come to agree with Christian that it would be good to show your
> model to a physics and/or numerical maths expert. Perhaps you can find a
> way for the errors to cancel out rather than accumulate.

I might try that.




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