On Dec 2, 5:40 pm, ggrafendorfer <[EMAIL PROTECTED]> wrote:
> Hi Michael,
>
> > You are using CDF == Complex Double Field, so numerical noise is to be
> > expected. IEEE arithmetic might be fast, but you pay for that speed
> > with imprecise results. It might be possible to compile without
> > optimization and get a "correct" result in that case, but that could
> > change by using another gcc release.
>
> OK, but if you write it this way it may be clearer what I mean:
>
> sage: i^2
> -1
> sage: CDF(_)
> -1.0 + 1.22460635382e-16*I
>
> namely that the result of i^2 should be exact, if I want performance I
> could write i^2.
Ok, this is strange indeed. Look at the last example:
----------------------------------------------------------------------
| Sage Version 3.2.1, Release Date: 2008-12-01 |
| Type notebook() for the GUI, and license() for information. |
----------------------------------------------------------------------
sage: CDF(-1)
-1.0
sage: CDF(i^2)
-1.0 + 1.22464679915e-16*I
sage: CDF(i)^2
-1.0 + 1.22464679915e-16*I
Could it be that the evaluation order of the last two operations is
the same?
> Georg
Cheers,
Michael
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