In my experience, general purpose constraint and SMT solvers tend to have poor performance compared to linear relaxation techniques found in mathematical optimization products like CPLEX (which also have constraints but from a limited repertoire). It depends on the nature of your constraints whether CPLEX will work, but I think it will for your problem.
On 9/20/19, 3:55 PM, "Friam on behalf of Steven A Smith" <[email protected] on behalf of [email protected]> wrote: Gary - I *patently don't* recommend my method, though it does have some charms. I recently was faced with a similar problem to yours where I needed to cut and install trim around the perimeter of the room (with door openings) I just layed hardwood floor in. Rather than go into it in detail (I already did that and realized it was a TL;DR as usual, so cut it) I will just say that I approach these problems as *satisficing* and *constraint* problems rather than *optimization*. Once I had a candidate layout, I simply looked at the results and determined that the *waste* was acceptable. Depending on the circumstances I sometimes prefer to have for example, 2 3' leftovers rather than 1 5' leftover, other times, vice-versa, depending on how I might use said leftovers in some future application (or hedging against a mistake in my measuring/cutting). Care to share what your actual conduit/pipe project is? - Steve > Thanks for the links, Peter. I will probably use that software or > similar, to get a quick solution, then look at the MOOCs. > > On Fri, Sep 20, 2019 at 2:52 PM Pieter Steenekamp > <[email protected]> wrote: >> Two possible approaches are: >> a) Solve the problem yourself. Use one or a combination of standard algorithms ( eg you mentioned linear programming and greedy algorithms, there are many more of course) and/or your own custom algorithm. If you wish to go this route and want to learn about the subject, I recommend the series of MOOCS by Stanford's Tim Roughgarden https://www.coursera.org/specializations/algorithms >> Or, I think yours is probably a knapsack -type problem and the MOOC https://www.coursera.org/learn/discrete-optimization covers that relatively well. >> b) But if you just want to get the solution you can use optimization software like https://www.ibm.com/za-en/products/ilog-cplex-optimization-studio (they have a free edition that will be good enough for your application) will solve it for you without you necessarily knowing how the software does it. >> >> On Fri, 20 Sep 2019 at 21:00, Gary Schiltz <[email protected]> wrote: >>> I'd like advice on possible ways to solve the following problem >>> (plumbers must surely face this all the time). I need to cut a set of >>> metal tubes of varying lengths from standard length (6 meter) >>> galvanized conduit stock. The goal is to find the number of tubes I >>> need to buy, and the order of cuts to produce the minimum amount of >>> leftover, unused tube. I'm interested in what types of solutions >>> people use for similar 1-dimensional problems, e.g. linear >>> programming, greedy algorithms, etc. (I've been Googling). I'm only >>> looking to cut around 15-25 pieces, so my gut feeling is that an >>> exhaustive search of all possible solutions, though probably NP-hard, >>> would be feasible to perform. Working programs, as well as libraries >>> in any language would be a bonus. >>> >>> ============================================================ >>> FRIAM Applied Complexity Group listserv >>> Meets Fridays 9a-11:30 at cafe at St. John's College >>> to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com >>> archives back to 2003: http://friam.471366.n2.nabble.com/ >>> FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove >> ============================================================ >> FRIAM Applied Complexity Group listserv >> Meets Fridays 9a-11:30 at cafe at St. John's College >> to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com >> archives back to 2003: http://friam.471366.n2.nabble.com/ >> FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove > ============================================================ > FRIAM Applied Complexity Group listserv > Meets Fridays 9a-11:30 at cafe at St. John's College > to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com > archives back to 2003: http://friam.471366.n2.nabble.com/ > FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com archives back to 2003: http://friam.471366.n2.nabble.com/ FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com archives back to 2003: http://friam.471366.n2.nabble.com/ FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove
