RE: [AMPL 11859] Multiplying and summing a column from a matrix with another column

[Robert Fourer]

Have you tried something like this?

sum {j in Nodes} a[i,j] * demand[j]

Of course this sum will need to be included in some constraint definition that is indexed over Subsets.

Bob Fourer
am...@googlegroups.com

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From: am...@googlegroups.com [mailto:am...@googlegroups.com] On Behalf Of Heidi
Sent: Thursday, April 21, 2016 11:14 AM
To: AMPL Modeling Language
Subject: [AMPL 11859] Multiplying and summing a column from a matrix with another column

Am trying to implement the VRP using set covering method.

Now I am trying to make sure the demand of each node on the route does not exceed the vehicle capacity

set Nodes := 0 1 2 3 4;
set Subsets := S1 S2 S3 S4 S5;

param demand:=
0 0
1 10
2 11
3 13
4 0;

param a (tr): =1 if subset covers node

S1 S2 S3 S4 S5:=
0 1 1 1 1 1
1 1 1 0 1 1
2 0 1 1 0 1
3 0 0 1 1 1
4 1 1 1 1 1

What I want to do is to multiply each column in a with the demand and sum it together to see if a route exceeds the vehicle capacity

e.g. for subset 1:

[ 0 ] [1]
[10] [1]
[11] * [0] and sum this to get 10
[13] [0]
[0 ] [1]