Re: [sage-devel] Simple integral raises AttributeError
On Mon, Dec 9, 2019 at 1:55 PM Thierry wrote:
>
> Hi,
>
> On Wed, Dec 04, 2019 at 07:38:34AM -0800, Eric Gourgoulhon wrote:
> > Hi,
> >
> > In Sage 9.0.beta8 we have
> >
> > sage: a = var('a')
> > sage: integrate(1/(x^4 + x^2 + a), x)
> > ...
> > AttributeError: 'RootSum' object has no attribute '_sage_'
> >
> > The same error occurs in Sage 8.9, but not in Sage 8.8 (and below). In Sage
> > 8.8, we have instead:
> >
> > sage: a = var('a')
> > sage: integrate(1/(x^4 + x^2 + a), x)
> > integrate(1/(x^4 + x^2 + a), x)
Fricas just returns the answer in radicals, if you call
sage: integrate(1/(x^4 + x^2 + a), x, algorithm='fricas')
with
sage: integrate(1/(x^5 + x^3 + a), x, algorithm='fricas')
one gets an error, for a reason similar to the RootSum thing for sympy
(i.e. it can express the integral as a sum over roots of a polynomial, it's
just Sage doesn't know how to parse it)
> >
> > Note that RootSum is a SymPy object. Actually, in Sage 9.0.beta8, forcing
> > the algorithm to 'maxima' yields the same result as in Sage 8.8:
> >
> > sage: integrate(1/(x^4 + x^2 + a), x, algorithm='maxima')
> > integrate(1/(x^4 + x^2 + a), x)
> >
> > So it seems that since Sage 8.9, when integrate() is not capable to find an
> > answer via Maxima, it tries SymPy but is not capable to translate the
> > result back to Sage. I could not find a ticket about this. Shall I open one?
>
> For what it worth, the change was done at
> https://trac.sagemath.org/ticket/27958
>
> Ciao,
> Thierry
>
>
> > Eric.
> >
> > PS: for the record, a primitive of 1/(x^4 + x^2 + a) is
> >
> > sage: b = sqrt(1 - 4*a)
> > sage: f = sqrt(2)/b*(arctan(sqrt(2)*x/sqrt(1 - b))/sqrt(1 - b) -
> > arctan(sqrt(2)*x/sqrt(1 + b))/sqrt(1 + b))
> >
> > as we can check:
> >
> > sage: diff(f, x).simplify_full()
> > 1/(x^4 + x^2 + a)
> >
> >
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>
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Re: [sage-devel] Simple integral raises AttributeError
Hi,
On Wed, Dec 04, 2019 at 07:38:34AM -0800, Eric Gourgoulhon wrote:
> Hi,
>
> In Sage 9.0.beta8 we have
>
> sage: a = var('a')
> sage: integrate(1/(x^4 + x^2 + a), x)
> ...
> AttributeError: 'RootSum' object has no attribute '_sage_'
>
> The same error occurs in Sage 8.9, but not in Sage 8.8 (and below). In Sage
> 8.8, we have instead:
>
> sage: a = var('a')
> sage: integrate(1/(x^4 + x^2 + a), x)
> integrate(1/(x^4 + x^2 + a), x)
>
> Note that RootSum is a SymPy object. Actually, in Sage 9.0.beta8, forcing
> the algorithm to 'maxima' yields the same result as in Sage 8.8:
>
> sage: integrate(1/(x^4 + x^2 + a), x, algorithm='maxima')
> integrate(1/(x^4 + x^2 + a), x)
>
> So it seems that since Sage 8.9, when integrate() is not capable to find an
> answer via Maxima, it tries SymPy but is not capable to translate the
> result back to Sage. I could not find a ticket about this. Shall I open one?
For what it worth, the change was done at
https://trac.sagemath.org/ticket/27958
Ciao,
Thierry
> Eric.
>
> PS: for the record, a primitive of 1/(x^4 + x^2 + a) is
>
> sage: b = sqrt(1 - 4*a)
> sage: f = sqrt(2)/b*(arctan(sqrt(2)*x/sqrt(1 - b))/sqrt(1 - b) -
> arctan(sqrt(2)*x/sqrt(1 + b))/sqrt(1 + b))
>
> as we can check:
>
> sage: diff(f, x).simplify_full()
> 1/(x^4 + x^2 + a)
>
>
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Re: [sage-devel] Simple integral raises AttributeError
Le mercredi 4 décembre 2019 18:37:15 UTC+1, Dima Pasechnik a écrit : > > sure, please open a ticket. > This is now https://trac.sagemath.org/ticket/28842 Please review. Eric. -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-devel/95dfeb17-2c9c-4349-9e75-1c5cedc01789%40googlegroups.com.
Re: [sage-devel] Simple integral raises AttributeError
sure, please open a ticket.
On Wed, 4 Dec 2019, 15:38 Eric Gourgoulhon, wrote:
> Hi,
>
> In Sage 9.0.beta8 we have
>
> sage: a = var('a')
> sage: integrate(1/(x^4 + x^2 + a), x)
> ...
> AttributeError: 'RootSum' object has no attribute '_sage_'
>
> The same error occurs in Sage 8.9, but not in Sage 8.8 (and below). In
> Sage 8.8, we have instead:
>
> sage: a = var('a')
> sage: integrate(1/(x^4 + x^2 + a), x)
> integrate(1/(x^4 + x^2 + a), x)
>
> Note that RootSum is a SymPy object. Actually, in Sage 9.0.beta8, forcing
> the algorithm to 'maxima' yields the same result as in Sage 8.8:
>
> sage: integrate(1/(x^4 + x^2 + a), x, algorithm='maxima')
> integrate(1/(x^4 + x^2 + a), x)
>
> So it seems that since Sage 8.9, when integrate() is not capable to find
> an answer via Maxima, it tries SymPy but is not capable to translate the
> result back to Sage. I could not find a ticket about this. Shall I open one?
>
> Eric.
>
> PS: for the record, a primitive of 1/(x^4 + x^2 + a) is
>
> sage: b = sqrt(1 - 4*a)
> sage: f = sqrt(2)/b*(arctan(sqrt(2)*x/sqrt(1 - b))/sqrt(1 - b) -
> arctan(sqrt(2)*x/sqrt(1 + b))/sqrt(1 + b))
>
> as we can check:
>
> sage: diff(f, x).simplify_full()
> 1/(x^4 + x^2 + a)
>
>
> --
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> "sage-devel" group.
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>
> .
>
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[sage-devel] Simple integral raises AttributeError
Hi,
In Sage 9.0.beta8 we have
sage: a = var('a')
sage: integrate(1/(x^4 + x^2 + a), x)
...
AttributeError: 'RootSum' object has no attribute '_sage_'
The same error occurs in Sage 8.9, but not in Sage 8.8 (and below). In Sage
8.8, we have instead:
sage: a = var('a')
sage: integrate(1/(x^4 + x^2 + a), x)
integrate(1/(x^4 + x^2 + a), x)
Note that RootSum is a SymPy object. Actually, in Sage 9.0.beta8, forcing
the algorithm to 'maxima' yields the same result as in Sage 8.8:
sage: integrate(1/(x^4 + x^2 + a), x, algorithm='maxima')
integrate(1/(x^4 + x^2 + a), x)
So it seems that since Sage 8.9, when integrate() is not capable to find an
answer via Maxima, it tries SymPy but is not capable to translate the
result back to Sage. I could not find a ticket about this. Shall I open one?
Eric.
PS: for the record, a primitive of 1/(x^4 + x^2 + a) is
sage: b = sqrt(1 - 4*a)
sage: f = sqrt(2)/b*(arctan(sqrt(2)*x/sqrt(1 - b))/sqrt(1 - b) -
arctan(sqrt(2)*x/sqrt(1 + b))/sqrt(1 + b))
as we can check:
sage: diff(f, x).simplify_full()
1/(x^4 + x^2 + a)
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