Re: Bug with Integrate in v7?
- To: mathgroup at smc.vnet.net
- Subject: [mg103148] Re: Bug with Integrate in v7?
- From: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>
- Date: Wed, 9 Sep 2009 04:44:09 -0400 (EDT)
- References: <h859sa$pva$1@smc.vnet.net>
Looks like a bug to me. I'd suggest submitting this to
support at wolfram.com.
Please note that Integrate[f, {x, -1, 1}, {y, -1, 1}, {z, -1, 1}]
equals Integrate[Integrate[Integrate[f, {z, -1, 1}], {y, -1, 1}], {x,
-1, 1}] and not Integrate[Integrate[Integrate[f, {x, -1, 1}], {y, -1,
1}], {z, -1, 1}]
(outermost integrand is given first). This should not make a
difference in this case though.
Cheers -- Sjoerd
On Sep 8, 11:58 am, kostka <kos... at gmail.com> wrote:
> Okay it took me an hour to track this down, and the only explanation I
> can see is that there is a bug in Mathematica v7 with Integral[] with
> multiple bounds.
>
> In v7.0 (answers should both be 512/27, only one of them is):
>
> In[1]:= f = (x - 1)^2*(y - 1)^2*(z - 1)^2;
> Integrate[f, {x, -1, 1}, {y, -1, 1}, {z, -1, 1}]
> Integrate[Integrate[Integrate[f, {x, -1, 1}], {y, -1, 1}], {z, -1, 1}]
>
> Out[2]= 0
>
> Out[3]= 512/27
>
> In v6.0 (correct behavior):
>
> In[1]:= f = (x - 1)^2*(y - 1)^2*(z - 1)^2;
> Integrate[f, {x, -1, 1}, {y, -1, 1}, {z, -1, 1}]
> Integrate[
> Integrate[Integrate[f, {x, -1, 1}], {y, -1, 1}], {z, -1, 1}]
>
> Out[2]= 512/27
>
> Out[3]= 512/27
>
> Serious bug, right? Or am I missing something obvious?
>
> Tim