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Re: How to remove external parentheses from a list

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  • Subject: [mg131529] Re: How to remove external parentheses from a list
  • From: David Bailey <dave at removedbailey.co.uk>
  • Date: Sat, 17 Aug 2013 02:09:23 -0400 (EDT)
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On 16/08/2013 11:53, Samuel Mark Young wrote:
> Hello,
>
> I'm looking for an easy way to remove the external parentheses from a list.  The list contains integration variables and their respective limits, it currently looks something like this:
>
> {{x1,a,b},{x2,c,d},...,{xn,y,z}}
>
> However, the Integrate (or NIntegrate function) in Mathematica wants me to write it like this:
>
> {x1,a,b},{x2,c,d},...,{xn,y,z}
> i.e. The external parentheses have been removed
>
> I've looked around online and seen suggestions for replacing the curly brackets "{" with a blank space " ", or using Apply (@@) but can't work out the correct syntax.
>
> Thanks for any help and advice!
>
> Regards,
> Sam
>
>
On 16/08/2013 11:53, Samuel Mark Young wrote:> Hello,
 >
 > I'm looking for an easy way to remove the external parentheses from a 
list.  The list contains integration variables and their respective 
limits, it currently looks something like this:
 >
 > {{x1,a,b},{x2,c,d},...,{xn,y,z}}
 >
 > However, the Integrate (or NIntegrate function) in Mathematica wants 
me to write it like this:
 >
 > {x1,a,b},{x2,c,d},...,{xn,y,z}
 > i.e. The external parentheses have been removed
 >
 > I've looked around online and seen suggestions for replacing the 
curly brackets "{" with a blank space " ", or using Apply (@@) but can't 
work out the correct syntax.
 >
 > Thanks for any help and advice!
 >
 > Regards,
 > Sam
 >
 >
Sequence@@ will remove a layer of parentheses inside another construct 
(such as Integrate). For example:

In[1]:= lim = {{x, 1, 10}};

In[2]:= Integrate[x^2, Sequence @@ lim]

Out[2]= 333

David Bailey
http://www.dbaileyconsultancy.co.uk




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