Originally posted by: stathis_d

Hello, 

i'm wondering if someone can help with the following. In one of my constraints i want to force the value 1 for a binary variable s[j], when :  variable x[j]=1 and, parameter  grade[j] (of the x[j]=1) has the highest value.

I use conditional constraint for this one but i can't find a way to somehow force cplex to choose the highest value from the remaining set.  I try to introduce a new parameter m=max[j in Locations]grade[j] but always choose the highest from all the values of grade[j]. So, I'm wondering if there is any other way to force the highest value from a set of prices, thanks in advance! 

Hi,

could

range r =1..10;

 

dvar boolean x[r];

 

int grade[i in r]=i;

 

int maxgrade=max(i in r) grade[i];

int imaxgrade=first({i | i in r:grade[i]==maxgrade});

 

subject to

{

x[imaxgrade]==1;

}

help ?

regards

Originally posted by: stathis_d

Hi Alex, 

thanks for your answer. I have tried couple of stuff  but doesn't seem to work. Using the: 

int maxgrade=max(i in r) grade[i]; 

it always choose the highest from the whole list.  What i am trying  to do is firstly to check if distance is between 1.5 and 2 so then x[j]=1 and from those x[j]=1 to choose only the one that has the highest grade[j].   

I am wondering also in the syntax that you indicate what is the use of first? Does it choose the first element or the max from the set of maxgrade? 

Hi

range r =1..10;

 

int x[i in r]=i mod 2;

 

int grade[i in r]=i;

 

int maxgrade=max(i in r:x[i]==1) grade[i];

int imaxgrade=first({i | i in r:grade[i]==maxgrade});

 

execute

{

writeln(imaxgrade) ;

}

will pick the biggest among the ones such as x[j]==1

I use first to pick the first one if the set is not a singleton

regards