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MathGroup Archive 1997

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Re: NIntegrate with variable region

  • To: mathgroup at smc.vnet.net
  • Subject: [mg6287] Re: [mg6254] NIntegrate with variable region
  • From: Paul Abbott <paul at physics.uwa.edu.au>
  • Date: Sat, 8 Mar 1997 00:26:07 -0500 (EST)
  • Organization: University of Western Australia
  • Sender: owner-wri-mathgroup at wolfram.com

Zvi Wiener wrote:

> I wish to take an indefinite integral of a piecewise
> continuous function. For example:
> 
> f[x_]:= Which[ x<0, 0, x<1, 1, x>=1, x];
> 
> I tried:
> lst = {-1,0,1,2};
> NIntegrate[ f[x], Prepend[lst,x]]
> 
> But the result was:
> 
> NIntegrate::vars:
>    Integration range specification Prepend[lst, x]
>      is not of the form {x, xmin, ..., xmax}.
> 
> NIntegrate[f[x], Prepend[lst, x]]

Prepend[lst,x] is not evaluated because 

	In[3]:= Attributes[NIntegrate]
	Out[3]= {HoldAll,Protected}

You need to evaluate the Integration range:

	In[4]:= NIntegrate[ f[x], Evaluate[Prepend[lst,x]]]
	Out[4]= 2.5

Cheers,
	Paul 

_________________________________________________________________ 
Paul Abbott
Department of Physics                       Phone: +61-9-380-2734 
The University of Western Australia           Fax: +61-9-380-1014
Nedlands WA  6907                         paul at physics.uwa.edu.au 
AUSTRALIA                           http://www.pd.uwa.edu.au/Paul

          God IS a weakly left-handed dice player
_________________________________________________________________


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