Hi Jason,
OK, thank you very much,
it's clear, now I understand the performance explanation when doing
'CDF(i^2)', sage in this case does not perform a simplification before
coercing to CDF, clearly (for performance reasons),
the key is the represantation of "i^2" as -1, so may this is not
good ?
ggrafendorfer wrote:
> Hi Jason,
> thanks for your suggestion and your detailed answer,
>
> but actually I did not start this thread for performance reasons,
> I did start it to ask why "i^2" is not treated like an exact symbolic
> expression in sage:
>
>
Hi Jason,
thanks for your suggestion and your detailed answer,
but actually I did not start this thread for performance reasons,
I did start it to ask why "i^2" is not treated like an exact symbolic
expression in sage:
--
| Sage
ggrafendorfer wrote:
> Hi Robert,
> this was not a misunderstanding, there is an "n" missing :-), I
> corrected it:
> I wanted to write
>
> then i^2 should also be of type CDF, but
>
> rather then
>
> the i^2 should also
>
> as an answer to your statement, namely that i^2 is getting turne
Hi Robert,
> > what I want to say is that I nevertheless don't understand why i^2 is
> > not be treated like a symbolic expression ...
> > I hope I will sometimes ..:-)
>
> In your case, it's not treated like a symbolic expression because
> it's not a symbolic expression.
Looks again like a misun
On Dec 2, 2008, at 6:27 PM, ggrafendorfer wrote:
> Hi Robert,
>>> Again, if I want performance I could use i^2.,
>>
>> Um... that's *slower*, right?
>
> I really did not expect that i^2. is slower than i^2,
> in my problem I needed performance, for this I wrote
> i = CDF(I)
> in the first line of
Hi Robert,
this was not a misunderstanding, there is an "n" missing :-), I
corrected it:
I wanted to write
then i^2 should also be of type CDF, but
rather then
the i^2 should also
as an answer to your statement, namely that i^2 is getting turned into
CDF(i)^CDF(2)
I hope this is clear no
Hi Robert,
> > Again, if I want performance I could use i^2.,
>
> Um... that's *slower*, right?
I really did not expect that i^2. is slower than i^2,
in my problem I needed performance, for this I wrote
i = CDF(I)
in the first line of my script, not just for performance, it can also
leed to error
On Dec 2, 2008, at 6:12 PM, ggrafendorfer wrote:
> Hi Robert
>> symbolic expression "i^2" is getting turned into CDF(i)^CDF(2).
>
> the i^2 should also be of type CDF, but
>
> sage: type(i^2)
>
Ah, I think I see the misunderstanding now. i^2 should not be of type
CDF, because i is not of type
On Dec 2, 2008, at 6:04 PM, ggrafendorfer wrote:
>> Perhaps we should special case for (small) integer powers, but that
>> would slow other stuff down. What's happening here is that the
>> symbolic expression "i^2" is getting turned into CDF(i)^CDF(2).
>> Simplification happens on printing, not o
Hi Robert,
> Perhaps we should special case for (small) integer powers, but that
> would slow other stuff down. What's happening here is that the
> symbolic expression "i^2" is getting turned into CDF(i)^CDF(2).
Then "i^2" should be of type CDF, but
sage: type(i^2)
Georg
--~--~-~--
Hi Robert
> symbolic expression "i^2" is getting turned into CDF(i)^CDF(2).
the i^2 should also be of type CDF, but
sage: type(i^2)
Georg
--~--~-~--~~~---~--~~
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> Perhaps we should special case for (small) integer powers, but that
> would slow other stuff down. What's happening here is that the
> symbolic expression "i^2" is getting turned into CDF(i)^CDF(2).
> Simplification happens on printing, not on construction.
>
> sage: CDF(simplify(i^2))
> -1.0
On Dec 2, 2008, at 5:40 PM, ggrafendorfer 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
>> optimizati
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
> > o
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
> cha
On Dec 2, 5:29 pm, ggrafendorfer <[EMAIL PROTECTED]> wrote:
> Hi,
Hi Georg,
> I'm using sage 3.2 (compiled from sources) on a 32-bit Core Duo
> machine running Debian Etch:
>
> I'm not sure if this bug,
> why does
>
> sage: CDF(i^2)
> -1.0 + 1.22460635382e-16*I
>
> I'm not complaining about th
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