Re: Re: Bug with Integrate in v7?
- To: mathgroup at smc.vnet.net
- Subject: [mg103277] Re: [mg103262] Re: Bug with Integrate in v7?
- From: DrMajorBob <btreat1 at austin.rr.com>
- Date: Sat, 12 Sep 2009 07:26:42 -0400 (EDT)
- References: <h859sa$pva$1@smc.vnet.net> <h87pdf$5f6$1@smc.vnet.net>
- Reply-to: drmajorbob at yahoo.com
NIntegrate fails on the whole interval, but succeeds if we break it into
two intervals:
g[x_] = Piecewise[{{Sin[x]^4, -\[Pi] <=
x <= -\[Pi]/2}, {Sin[x]^10, -\[Pi]/2 <=
x <= \[Pi]/2}, {Sin[x]^16, \[Pi]/2 < x <= \[Pi]}}];
NIntegrate[g@x Sin[x], {x, -\[Pi], 0}] +
NIntegrate[g@x Sin[x], {x, 0, Pi}] -
Integrate[g@x Sin[x], {x, -Pi, Pi}]
-4.59355*10^-14
Bobby
On Fri, 11 Sep 2009 18:57:19 -0500, guerom00 <guerom00 at gmail.com> wrote:
> I stumbled on this one :
>
> In[59]:= f=Piecewise[{
> {Sin[x]^4,-\[Pi]<=x<=-\[Pi]/2},
> {Sin[x]^10,-\[Pi]/2<=x<=\[Pi]/2},
> {Sin[x]^16,\[Pi]/2<x<=\[Pi]}
> }];
> NIntegrate[f Sin[x],{x,-\[Pi],\[Pi]}]
> Integrate[f Sin[x],{x,-\[Pi],\[Pi]}]
>
> Out[60]= 0.
> Out[61]= -(25576/109395)
>
--
DrMajorBob at yahoo.com