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Re: Sum of terms --> list

  • To: mathgroup at smc.vnet.net
  • Subject: [mg110593] Re: Sum of terms --> list
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Sun, 27 Jun 2010 04:55:21 -0400 (EDT)

expr = a + b + c;

List @@ expr

{a,b,c}

expr /. Plus -> List

{a,b,c}

expr = a*b*c;

List @@ expr

{a,b,c}

expr /. Times -> List

{a,b,c}

expr = a*b + c + e*f*g;

List @@ expr

{a b,c,e f g}

List @@ (List @@@ expr) // Quiet

{c,{a,b},{e,f,g}}

expr /. {Times -> List, Plus -> List}

{{a,b},c,{e,f,g}}


Bob Hanlon

---- uno <dxcqp2000 at gmail.com> wrote: 

=============
Hi,

I have an expression that is a sum of terms, like
    a+b+c
and I want to convert it to a list, with as many elements as the
number of terms in the sum of terms, and with each element being each
of the terms, like
    {a,b,c}

Also, the same to go from a product of terms like
    a*b*c
to a list like
    {a,b,c}

Is there any way, in Mathematica, to do this?
I've been looking for an answer in the Help, and in the web, with no
help.

I ask this because "a*b+c+e*f*g" needs to be evaluated by an external
(.NET) program, which is not able to parse expressions. I have to
"break" everything inside Mathematica, before sending information to
that external program, which will evaluate that expression many times,
for different values of {a,b,c,d,e,f,g}.

Thank you.





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