- Apr 10, 2012 11:17:15 AM (2 years ago)
- 1 edited
r1853 r1855 2392 2392 parameters[numberParameters++] = 2393 2393 CbcOrClpParam("mips!tart", "reads an initial feasible solution from file", 2394 CBC_PARAM_ACTION_MIPSTART, 3); 2395 parameters[numberParameters-1].setLonghelp 2396 ( 2397 "This will read a file containing an initial feasible solution. \ 2398 Files containing previously saved solution files (in cbc format) are directly read. \ 2399 If the value of only a subset of variables is informed the solver automatically tries to fill the remaining values. \ 2394 CBC_PARAM_ACTION_MIPSTART); 2395 parameters[numberParameters-1].setLonghelp 2396 ("\ 2397 The MIPStart allows one to enter an initial integer feasible solution \ 2398 to CBC. Values of the main decision variables which are active (have \ 2399 non-zero values) in this solution are specified in a text file. The \ 2400 text file format used is the same of the solutions saved by CBC, but \ 2401 not all fields are required to be filled. First line may contain the \ 2402 solution status and will be ignored, remaning lines contain column \ 2403 indexes, names and values as in this example:\n\ 2404 \n\ 2405 Stopped on iterations - objective value 57597.00000000\n\ 2406 0 x(1,1,2,2) 1 \n\ 2407 1 x(3,1,3,2) 1 \n\ 2408 5 v(5,1) 2 \n\ 2409 33 x(8,1,5,2) 1 \n\ 2410 ...\n\ 2411 \n\ 2412 Column indexes are also ignored since pre-processing can change them. \ 2413 There is no need to include values for continuous or integer auxiliary \ 2414 variables, since they can be computed based on main decision variables. \ 2415 Starting CBC with an integer feasible solution can dramatically improve \ 2416 its performance: several MIP heuristics (e.g. RINS) rely on having at \ 2417 least one feasible solution available and can start immediately if the \ 2418 user provides one. Feasibility Pump (FP) is a heuristic which tries to \ 2419 overcome the problem of taking too long to find feasible solution (or \ 2420 not finding at all), but it not always suceeds. If you provide one \ 2421 starting solution you will probably save some time by disabling FP. \ 2422 \n\n\ 2423 Knowledge specific to your problem can be considered to write an \ 2424 external module to quickly produce an initial feasible solution - some \ 2425 alternatives are the implementation of simple greedy heuristics or the \ 2426 solution (by CBC for example) of a simpler model created just to find \ 2427 a feasible solution. \ 2428 \n\n\ 2429 Question and suggestions regarding MIPStart can be directed to\n\ 2430 firstname.lastname@example.org.\ 2400 2431 "); 2401 2432 parameters[numberParameters++] =
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