Huh.
Whomever looks at this issue should note that there are now two
distinct problems raised in this thread: the original issue regarding
why f.integral(9,16) below remains unevaluated, and tDavid's question
of why the two answers are different.
On Jun 21, 9:01 am, "David Joyner" <[EMAIL PROTECTED]> wrote:
> Unless 24.9... = -24.9..., there seems to be a bug:
>
> sage: f = sqrt(25-x)*sqrt(1+1/(4*(25-x)))
> sage: f.integral(x,9,16)
> integrate(sqrt(1/(4*(25 - x)) + 1)*sqrt(25 - x), x, 9, 16)
> sage: f.nintegral(x,9,16)
> (24.9153783348643, 2.7661626694613149e-13, 21, 0)
> sage: g = f.simplify_radical()
> sage: g.integral(x,9,16)
> I*(65*sqrt(65)*I/6 - 37*sqrt(37)*I/6)/2
> sage: ans = g.integral(x,9,16)
> sage: ans.real()
> (37*sqrt(37)/6 - 65*sqrt(65)/6)/2
> sage: RR(ans.real())
> -24.9153783348643
>
> On Sat, Jun 21, 2008 at 8:51 AM, Roger <[EMAIL PROTECTED]> wrote:
>
> > Can someone explain why sage (or perhaps maxima, I don't know) manages
> > to evaluate the indefinite integral below, but fails to give a numeric
> > answer to the definite integral? Seems odd to me. (version 3.02
> > running on Mac OS X)
>
> > sage: var('x')
> > x
> > sage: integral(sqrt(25-x)*sqrt(1+1/(4*(25-x))),x)
> > sqrt(4*x - 101)*(4*I*x - 101*I)/12
> > sage: integral(sqrt(25-x)*sqrt(1+1/(4*(25-x))),x,9,16)
> > integrate(sqrt(1/(4*(25 - x)) + 1)*sqrt(25 - x), x, 9, 16)
>
> > Thanks,
> > Roger
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to sage-support@googlegroups.com
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/sage-support
URLs: http://www.sagemath.org
-~----------~----~----~----~------~----~------~--~---
