Re: Adding elements of a matrix
- To: mathgroup at smc.vnet.net
- Subject: [mg40609] Re: Adding elements of a matrix
- From: bobhanlon at aol.com (Bob Hanlon)
- Date: Fri, 11 Apr 2003 02:01:18 -0400 (EDT)
- References: <b738oh$o7l$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
(mat = Array[m, {3,3}]);
For the sum of every term m[[i,j]] with i < j
Sum[mat[[i,j]], {j, Length[mat]},{i,j-1}]
m[1,2]+m[1,3]+m[2,3]
For the sum of every term m[[i,j]] with i <= j
Sum[mat[[i,j]], {j, Length[mat]},{i,j}]
m[1,1]+m[1,2]+m[1,3]+m[2,2]+m[2,3]+m[3,3]
Bob Hanlon
In article <b738oh$o7l$1 at smc.vnet.net>, Rebeca Choy <rchoy at ula.ve> wrote:
<<
Subject: Adding elements of a matrix
From: Rebeca Choy <rchoy at ula.ve>
To: mathgroup at smc.vnet.net
Date: Thu, 10 Apr 2003 08:07:45 +0000 (UTC)
Hi,
How can I add in Mathematica every element of a matrix without adding
twice the mixed terms?
for example i have a matrix m[[i,j]] and i want to add every term where
i<j (this is to avoiding adding twice the same number)
Can I do it with Sum?
Rebeca Choy
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