On Mon, Oct 23, 2023 at 12:35 AM Mild Shock <[email protected]> wrote:
>
> >  There is 'romberg' in NumericalQuadrature package.
>
> Is this something under the heading "FriCAS API"?
>
> I have no clue how to load a package, and I even
> don't understand how I get into a ")" prompt?

")" is not a prompt, it's part of a command you type at "->" prompt,

>
> All I see when I start FriCAS is a "->" prompt:
>
> (1) ->
>
>
> Waldek Hebisch schrieb am Sonntag, 22. Oktober 2023 um 23:20:17 UTC+2:
>>
>> On Sat, Oct 21, 2023 at 03:49:08PM -0700, Mild Shock wrote:
>> > The slope multiplied by the distance would be,
>> > using real-valued root (the Wolfram Alpha assumption):
>> >
>> > integral_0^(2 π) 1/100 (2 + cos(t)) cos(t)^(1/3) dt = 0.0364298
>> > https://www.wolframalpha.com/input?i=integ_0%5E%282*pi%29+cos%28t%29%5E%281%2F3%29+%282%2Bcos%28t%29%29+%2F100+dt&assumption=%22%5E%22+-%3E+%22Real%22
>> >
>> > But I am not sure whether the interval - π/2 to π/2,
>> > as you suggest, would give me the slope.
>>
>> I suggested splitting interval into two parts: one where cos is
>> positive and one where it is negative. You then need to add
>> both parts, taking only one would be wrong.
>>
>> > The factor
>> > cos(t)^(1/3) is indeed positive in this interval, but
>> >
>> > the integrand itself is not symmetric, for example the
>> > range π/2 to π is not a mirror of the range 0 to π/2. Also
>> > the smaller interval doesn't improve integrability:
>> >
>> > (1) -> integrate(cos(t)^(1/3)*(2+cos(t))/100, t = -%pi/2..%pi/2, "noPole")
>> >
>> > (1) "failed"
>>
>> Yes, I was illustrating general principle. Above the approach
>> breaks down because FriCAS can not compute indefinite integral.
>> However, in cases when FriCAS can compute indefinite integral
>> you may have trouble due to singularities and choice of
>> brnaches. Splitting is a fairly general method to limit
>> troubles caused by singularities.
>>
>> > Maybe there is a function in FriCAS for some
>> > numerical integral algorithm? Have to check the FriCAS
>> > manual, maybe I find something.
>>
>> There is 'romberg' in NumericalQuadrature package.
>>
>> --
>> Waldek Hebisch
>
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