Subject: Maxima asks about sign of integration(!) variable
From: John Lapeyre
Date: Wed, 25 Sep 2013 23:45:59 +0200
On 09/25/2013 09:26 PM, Richard Fateman wrote:
> In Mathematica, the answer came out
> 3/16 (65697 + 127 I Sqrt[3])
> or 12318.2 + 41.2445 I
>
> Doing NIntegrate in Mathematica provided
>
> 12318.1 + 41.2326 I
>
My nintegrate function, which calls quadpack, seems to agree more
with Mathematica's exact answer than it's numerical answer. I've
seen that more than once.
(%i5) nintegrate(sqrt(1+(4*x^(1/3)-1/16*x^((-1)/3))^2),[x,-8,512]);
(%o5) [41.24445772554166*%i+12318.18747666083,1.5204793641032666e-5,2268,
"no problems"]
I have been trying a bit to extend it to do oscillatory integrals
as well, eg. cos(x^2) --> cos(u)/sqrt(u). But changevar is broken,
... so it will take a while.
-- John