Edwin Woollett wrote:
> On Dec 5, 2007, Daniel Lakeland wrote
>
> If I want to numerically calculate integrate(f(x),x,minf,inf) in
> quadpack, I have to say
>
> quad_qagi(f(x),x,minf,both)
>
> which is so unintuitive that even after reading the docs several times
> I spent about half an hour figuring it out. Worse yet, if I say
>
> quad_qagi(f(x),x,minf,inf) I get half the integral that I expect (it
> integrates -inf to 0)
>
>
> On Dec 5, 2007, Raymond Toy wrote:
>
> You are right. It is confusing. The maxima interface is a very thin
> layer over the actual qagi function. That's my excuse, anyway. :-)
>
> The interface should be changed to recognize recognize a to inf, minf to
> a, and minf to inf. It should give errors for other cases.
>
> I'll look into doing this.
>
>
> I can't get minf to work with quad_qagi
> in any of the various permutations
>
> (%i1) display2d:false$
> (%i2) quad_qagi(exp(-x^2),x,0,inf);
> (%o2) [0.88622692545276,7.101318390915455E-9,135,0]
> (%i3) quad_qagi(exp(-x^2),x,minf,0);
> (%o3) quad_qagi(%e^-x^2,x,minf,0,epsrel = 1.0E-8,epsabs = 0.0,limit = 200)
> (%i4) quad_qagi(exp(-x^2),x,minf,inf);
> (%o4) quad_qagi(%e^-x^2,x,minf,inf,epsrel = 1.0E-8,epsabs = 0.0,limit = 200)
> (%i5) quad_qagi(exp(-x^2),x,minf,both);
> (%o5) quad_qagi(%e^-x^2,x,minf,both,epsrel = 1.0E-8,epsabs = 0.0,limit =
> 200)
>
>
Oops. I never did anything about this. Which explains why nothing you
tried works. You still have to specify the arguments as specified in
the help.
Ray