I agree. I (or Chonawee) will go ahead and place the order for CPLEX. I think 
that this will provide us with a great set of tools.
-Samer




	Pinnamaneni Krishnarao@ECT
	05/24/00 01:34 PM
		
		 To: Samer Takriti/Enron Communications@ENRON COMMUNICATIONS@ENRON, Tom 
Halliburton/Corp/Enron@ENRON
		 cc: Grant Masson/HOU/ECT@ECT, Stinson Gibner/HOU/ECT@ECT, Chonawee 
Supatgiat/Corp/Enron@Enron, Vince J Kaminski/HOU/ECT@ECT
		 Subject: Re: CPLEX

I talked to Vince about the optimization software issue. Vince said that if 
there are technical reasons for having two different packages and the 
benefits outweigh the costs of maintaining two licenses, we can go ahead and 
buy both. In my view, it is a great advantage to have both, as each has its 
own strengths relative to the other. We have spent some time trying to come 
up with one package that solves all of our problmes without success. There is 
no point is wasting more time on this effort. Let's go ahead and purchase 
both. 

Krishna.



From: Samer Takriti@ENRON COMMUNICATIONS on 05/24/2000 10:22 AM
To: Tom Halliburton/Corp/Enron@ENRON
cc: Grant Masson/HOU/ECT@ECT, Pinnamaneni Krishnarao/HOU/ECT@ECT, Stinson 
Gibner/HOU/ECT@ECT, Chonawee Supatgiat/Corp/Enron@Enron 
Subject: Re: CPLEX  

Tom,
Vince prefers to have one software package (if possible). It is my 
understanding that special ordered sets are recognized automatically 
(internally) by Cplex. This seems to be the case for both Cplex and OSL 
according to AMPL's web page and other references (check 
http://www.ampl.com/cm/cs/what/ampl/FAQ/index.html#HowcanIusethesolver'sspecia
lorderedsetsfeature). As a result, the Cplex people feel that there is no 
need to provide the user with the tools to represent special-ordered sets in 
OPL. As a matter of fact, the incapability of Xpress to recognize them 
automatically concerns me. 
If you have special requirements, C code may be used to pass the information 
to the solver (which is straight forward; all of Chonawee's testing was done 
this way). Chonawee's benchmark shows a superior performance by Cplex (which 
you indicated yourself in an earlier message).
If you feel that Xpress is the only way to go, then feel free to purchase it 
(the purchase order is on hold for the time being). However, we need to check 
with Vince first. I strongly feel that we should have one solver in order to 
minimize cost and contractual headaches.
Let us try to get this issue resolved by this afternoon. Thanks.
-Samer