Solver with binary variable
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From: maywood on 22 Dec 2009 05:02 Hello everyone! I still got a problem with a Solver optimization. I hope you can help me. There is a machine which can produce 2 products separately. In my optimization problem there are several constraints: - Sum of Production of X & Y is equal to or less than capacity of the machine - Demand of X & Y must be satisfied (Stock (t-1) – Demand + Production + Purchase – Stock (t) = 0 ) in each month - Stocks must be equal to or less than maximum stock & not less than minimum stock - And: o The production of Y should happen in batches of 500 (if 500 is lower than capacity) oThat means that Y is not produced each month. It is only produced, when Stock of Y will be too low (Row: “Calculated Production”) For the last constraint I implemented a binary variable which stands for Production of Y Yes/No. The objective is a minimization of fictive costs: The sum of Stocks * Stock Costs + the sum of Production * Production Costs + Sum of Purchase * Purchase Costs I think I am still missing one or more constraints. You can have a look in the example file. 1. There is a purchase of Y in February. Why not 0 in February and all the required purchase in March? 2. There are also purchases of Y in May & June. Why not in July? 3. There is a purchase of X in March. But there is still free capacity in March? http://www.herber.de/bbs/user/66765.xls |