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Enron Mail |
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
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