On Wed, Mar 11, 2009 at 2:52 PM, mark mcclure <mcmcc...@unca.edu> wrote:
>
>
>
> On Mar 11, 2:46 pm, David Joyner <wdjoy...@gmail.com> wrote:
>> sage: t = var("t")
>> sage: numerical_integral(abs(sin(t^2)),0,3)
>> (1.7024100330599248, 1.5397333279914378e-06)
>>
>> because AFAIK, integrate(abs(sin(t*t)),t,0,3)
>> cannot be computed in closed form.
>
> Mathematica returns the result in terms of Fresnel functions.


Point taken. However, integrate(abs(sin(t*t)),t,0,3) is
by definition (since sin(x)>0 in that interval) the
Fresnel integral S(3), http://en.wikipedia.org/wiki/Fresnel_integral,
and just renaming it doesn't make it a closed form expression:-)


> Maxima can find the indefinite integral in terms of the error
> function.  What Maxima *can't* do is deal with absolute values
> in a definite integral.  Try:
> integrate(abs(sin(t)), t, 0, pi)
>
> The result returns unevaluated, even though the integrand is
> positive on the integral.  I think I saw that on the Maxima
> discussion group a bit ago.
>
> Mark McClure
>
> >
>

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