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MathGroup Archive 2006

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Re: Converting an expression to a list of terms?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg71555] Re: Converting an expression to a list of terms?
  • From: "dimitris" <dimmechan at yahoo.com>
  • Date: Thu, 23 Nov 2006 05:41:25 -0500 (EST)
  • References: <200611200743.CAA09240@smc.vnet.net><ejtdhl$j0v$1@smc.vnet.net>

It's not a good programming practise to treat independently each
element of one expression.
Treat the expession as a whole.

lst=a+b-c+d-e;

List@@lst

{a,b,-c,d,-e}

lst/.x_+y___\[RuleDelayed]{x,y}

{a,b,-c,d,-e}

I highly recomend you reading Chapter 2 of the Mathematica Book.

FrontEndExecute[{HelpBrowserLookup["MainBook", "2"]}]

Regards
Dimitris

János wrote:
> On Nov 20, 2006, at 2:43 AM, AES wrote:
>
> > How to convert an expression consisting of a sum of terms in an Output
> > cell:
> >
> >    A + B - C + . . .
> >
> > (where A, B, C are themselves product expressions) to a list
> >
> >    {A, B, -C, . . . }
> >
> > in some easier fashion than doing it by hand using Find and Replace?
>
> My newbie approach would be:
>
> In[1]:=
> expr = a + b - c + d - e;
>
> In[2]:=
> Table[expr[[i]],
>    {i, 1, Length[expr]}]
> Out[2]=
> {a, b, -c, d, -e}
>
> János
>
>
> ----------------------------------------------
> Trying to argue with a politician is like lifting up the head of a
> corpse.
> (S. Lem: His Master Voice)


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