[79] in mathematical software users group
No subject found in mail header
daemon@ATHENA.MIT.EDU (siman@BOURBAKI.MIT.EDU)
Fri Apr 16 17:28:54 1993
Date: Fri, 16 Apr 93 17:28:03 EDT
From: siman@BOURBAKI.MIT.EDU
To: msug@MIT.EDU
Hi Everybody,
I have a problem about using maple (or mathematica) to perform a certain
calculation (see below). My school's consultant suggests that I contact this
newgroup. Any advice are highly welcome!
By the way, since I don't have access to this newgroup, I'd really appreciated
if you could email me a copy of your response. THANKS!!
Siman Wong
> Hi Consultant,
>
> I'd like to numerically integrate a function with 4 variables:
>
> \int_{ abs(x1), ... , abs(x4) <=1 } f(x1, ..., x4)
>
> But maple's "int" function seems to accept functions of one variable only,
> and I couldn't break my 4-fold integral into an iterated one. Any suggestion
> as to what I can do?
> (my integral is concentrated near the origin, so if I were to break the
> region of integration into grid, it would have to be a *very* fine one, and
> hence a real pain...)
>
> Incidentally, suppose the integral does break up into an iterated integral:
>
> /a /a(x1) /a(x1,x2) /a(x1,x2,x3)
> | | | |
> | | | | f(x1, ..., x4) dx4...dx1
> | | | |
> /b /b(x1) /b(x1,x2) /b(x1,x2,x3)
>
> then what should I do? --- the point is that, even in this case, the three
> inner integral's limit of integration are *functions*, not just numbers.
>
> Thanks!
> Siman
>
p.s. I'm happy to do this calculation in maple, mathematica, or even call an
external C subroutine.
