Changeset 1856


Ignore:
Timestamp:
Apr 15, 2012 5:14:22 AM (8 years ago)
Author:
forrest
Message:

help from stable

File:
1 edited

Legend:

Unmodified
Added
Removed
  • trunk/Clp/src/CbcOrClpParam.cpp

    r1852 r1856  
    23922392      parameters[numberParameters++] =
    23932393          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     ("\
     2397The MIPStart allows one to enter an initial integer feasible solution \
     2398to CBC. Values of the main decision variables which are active (have \
     2399non-zero values) in this solution are specified in a text  file. The \
     2400text file format used is the same of the solutions saved by CBC, but \
     2401not all fields are required to be filled. First line may contain the \
     2402solution status and will be ignored, remaning lines contain column \
     2403indexes, names and values as in this example:\n\
     2404\n\
     2405Stopped 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\
     2412Column indexes are also ignored since pre-processing can change them. \
     2413There is no need to include values for continuous or integer auxiliary \
     2414variables, since they can be computed based on main decision variables. \
     2415Starting CBC with an integer feasible solution can dramatically improve \
     2416its performance: several MIP heuristics (e.g. RINS) rely on having at \
     2417least one feasible solution available and can start immediately if the \
     2418user provides one. Feasibility Pump (FP) is a heuristic which tries to \
     2419overcome the problem of taking too long to find feasible solution (or \
     2420not finding at all), but it not always suceeds. If you provide one \
     2421starting solution you will probably save some time by disabling FP. \
     2422\n\n\
     2423Knowledge specific to your problem can be considered to write an \
     2424external module to quickly produce an initial feasible solution - some \
     2425alternatives are the implementation of simple greedy heuristics or the \
     2426solution (by CBC for example) of a simpler model created just to find \
     2427a feasible solution. \
     2428\n\n\
     2429Question and suggestions regarding MIPStart can be directed to\n\
     2430haroldo.santos@gmail.com.\
    24002431");
    24012432     parameters[numberParameters++] =
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