SCIP is a framework to solve constraint integer programs (CIPs) and mixed-integer nonlinear programs. In particular,
See the web site of SCIP for more information about licensing and to download SCIP.
If you are new to SCIP and don't know where to start you should have a look at the first steps walkthrough .
This manual gives an accessible introduction to the functionality of the SCIP code in the following chapters
Setup and news
Tutorials and guides
Examples and applications
References
Let's consider the following minimal example in LP format. A 4-variable problem with a single, general integer variable and three linear constraints
Maximize obj: x1 + 2 x2 + 3 x3 + x4 Subject To c1: - x1 + x2 + x3 + 10 x4 <= 20 c2: x1 - 3 x2 + x3 <= 30 c3: x2 - 3.5 x4 = 0 Bounds 0 <= x1 <= 40 2 <= x4 <= 3 General x4 End
Saving this file as "simple.lp" allows to read it into SCIP and solve it by calling the scip binary with the -f
flag to solve the problem from the provided file and exit.
reads and optimizes this model in no time:
SCIP version 9.1.1 [precision: 8 byte] [memory: block] [mode: optimized] [LP solver: Soplex 7.1.1] [GitHash: NoGitInfo] Copyright (c) 2002-2024 Zuse Institute Berlin (ZIB) External libraries: Readline 8.2 GNU library for command line editing (gnu.org/s/readline) Soplex 7.1.1 Linear Programming Solver developed at Zuse Institute Berlin (soplex.zib.de) [GitHash: NoGitInf] CppAD 20180000.0 Algorithmic Differentiation of C++ algorithms developed by B. Bell (github.com/coin-or/CppAD) ZLIB-NG 2.2.2 General purpose compression library by J. Gailly and M. Adler (zlib.net) GMP 6.3.0 GNU Multiple Precision Arithmetic Library developed by T. Granlund (gmplib.org) ZIMPL 3.6.2 Zuse Institute Mathematical Programming Language developed by T. Koch (zimpl.zib.de) AMPL/MP 690e9e7 AMPL .nl file reader library (github.com/ampl/mp) PaPILO 2.3.1 parallel presolve for integer and linear optimization (github.com/scipopt/papilo) (built with TBB) Nauty 2.8.9 Computing Graph Automorphism Groups by Brendan D. McKay (users.cecs.anu.edu.au/~bdm/nauty) sassy 1.1 Symmetry preprocessor by Markus Anders (github.com/markusa4/sassy) Ipopt 3.14.16 Interior Point Optimizer developed by A. Waechter et.al. (github.com/coin-or/Ipopt) user parameter file <scip.set> not found - using default parameters read problem <inc/simpleinstance/simple.lp> ============ original problem has 4 variables (0 bin, 1 int, 0 impl, 3 cont) and 3 constraints presolving: (round 1, fast) 2 del vars, 1 del conss, 0 add conss, 4 chg bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 0 impls, 0 clqs (round 2, fast) 2 del vars, 1 del conss, 0 add conss, 6 chg bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 0 impls, 0 clqs (round 3, fast) 2 del vars, 1 del conss, 0 add conss, 7 chg bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 0 impls, 0 clqs (0.0s) running MILP presolver (0.0s) MILP presolver found nothing (0.0s) probing cycle finished: starting next cycle (0.0s) symmetry computation started: requiring (bin +, int +, cont +), (fixed: bin -, int -, cont -) (0.0s) no symmetry present (symcode time: 0.00) presolving (4 rounds: 4 fast, 1 medium, 1 exhaustive): 2 deleted vars, 1 deleted constraints, 0 added constraints, 7 tightened bounds, 0 added holes, 0 changed sides, 0 changed coefficients 2 implications, 0 cliques presolved problem has 3 variables (1 bin, 0 int, 0 impl, 2 cont) and 2 constraints 2 constraints of type <linear> Presolving Time: 0.00 time | node | left |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr| dualbound | primalbound | gap | compl. t 0.0s| 1 | 0 | 0 | - | trivial| 0 | 3 | 2 | 0 | 0 | 0 | 0 | 0 | 1.630000e+02 | 3.400000e+01 | 379.41%| unknown t 0.0s| 1 | 0 | 0 | - | trivial| 0 | 3 | 2 | 0 | 0 | 0 | 0 | 0 | 1.630000e+02 | 5.300000e+01 | 207.55%| unknown p 0.0s| 1 | 0 | 0 | - | locks| 0 | 3 | 2 | 2 | 0 | 0 | 0 | 0 | 1.630000e+02 | 1.225000e+02 | 33.06%| unknown 0.0s| 1 | 0 | 2 | - | 613k | 0 | 3 | 2 | 2 | 0 | 0 | 0 | 0 | 1.252083e+02 | 1.225000e+02 | 2.21%| unknown 0.0s| 1 | 0 | 2 | - | 613k | 0 | 3 | 2 | 2 | 0 | 0 | 0 | 0 | 1.252083e+02 | 1.225000e+02 | 2.21%| unknown 0.0s| 1 | 0 | 3 | - | 617k | 0 | 3 | 2 | 3 | 1 | 1 | 0 | 0 | 1.225000e+02 | 1.225000e+02 | 0.00%| unknown 0.0s| 1 | 0 | 3 | - | 617k | 0 | 3 | 2 | 3 | 1 | 1 | 0 | 0 | 1.225000e+02 | 1.225000e+02 | 0.00%| unknown SCIP Status : problem is solved [optimal solution found] Solving Time (sec) : 0.01 Solving Nodes : 1 Primal Bound : +1.22500000000000e+02 (3 solutions) Dual Bound : +1.22500000000000e+02 Gap : 0.00 %