Stack Overflow
Stack Overflow

Questions tagged [scip]

Software package for solving mixed integer linear and nonlinear programming problems and part of the SCIP Optimization Suite. SCIP is distributed under the Apache 2.0 license and its C source code is available.

Mixed integer programming is the task to optimize a linear functional over a polyhedron, where some or all variables are constrained to be integer. The SCIP Optimization suite offers a branch-and-cut implementation, and a standalone implementation of the Simplex algorithm, called SoPlex, to solve linear programming problems.

Furthermore, SCIP comes with a modelling language ZIMPL that aims to ease the task of formulating mixed integer programming problems, a parallel solver called UG, and an implementation of the branch-and-cut-and-price algorithm called GCG.

The SCIP Optimization suite is one of the fastest implementations whose source code is available. It is written in C, but also offers a C++ interface.

<= 03.11.2022:
  • SCIP is free for academic research and can be licensed for commercial use.
>= 04.11.2022:
  • SCIP (as well as SoPlex) is distributed under the Apache 2.0 license.
409 questions
12
votes
2 answers

Solving an integer linear program: why are solvers claiming a solvable instance is infeasible?

I'm trying to solve integer programming problems. I've tried both use SCIP and LPSolve For example, given the final values of A and B, I want to solve for valA in the following C# code: Int32 a = 0, b = 0; a = a*-6 + b + 0x74FA - valA; b = b/3 + a +…
Craig Gidney
  • 17,763
  • 5
  • 68
  • 136
8
votes
1 answer

Speed of CPLEX vs CPLEX using SCIP

I am new to LP and have only briefly used PuLP in Python. Why is there a speed difference between SCIP 3.2.1 - CPLEX 12.63 and CPLEX 12.6.3? Doesn't SCIP still use CPLEX for solving? Why will someone use SCIP with CPLEX solver, instead of using…
Nyxynyx
  • 61,411
  • 155
  • 482
  • 830
5
votes
2 answers

Use of threads in SCIP

In the list of SCIP's parameters I see three types of references to the use of threads: lp/threads (threads used for solving the LP, which don't matter when using SoPlex, according to this question). parallel/{min, max}threads (number of threads…
rocarvaj
  • 546
  • 4
  • 19
4
votes
1 answer

parameterized vector with PySCIPopt

I'm attempting to use PySCIPopt to solve a traditional Ax-b + constraints type of problem. I have many values of b, and I need to run the optimizer on each of them. How can I reuse the setup? Second question, what is the equivalent of norm in…
Brannon
  • 5,324
  • 4
  • 35
  • 83
4
votes
0 answers

Installation problems of PySCIPOpt on Windows

when I run pip install pyscipopt I get the following error: build\lib.win32-3.7\pyscipopt\scip.cp37-win32.pyd : fatal error LNK1120: 311 unresolved externals error: command 'C:\\Program Files (x86)\\Microsoft Visual…
Michael Grant Warshowsky
  • 128
  • 2
  • 9
4
votes
2 answers

SCIP Customized settings not loaded

I have defined customized settings in a file called scip.set and put in in myscipdir/settings. The settings contain limits/time = 86400 limit/memory = 61440 lp/threads = 6 However, SCIP doesn't seems to load the customized settings,…
twfx
  • 1,664
  • 9
  • 29
  • 56
3
votes
2 answers

Multiple knapsack problem with no solution but finding a way to remove item(s) that are preventing a solution

I am trying to find a way to have as few boxes as possible that fit bags of chemicals. A box cannot have weight more than 3.3 kg but have to be higher than 2.7 kg. I came across Google's OR tools but I am struggling to program the constraints. When…
zoc99
  • 105
  • 1
  • 5
3
votes
0 answers

Possibility to obtain iterations data in SCIP .sol file

I am using SCIP solver (with AMPL executable file) in PYOMO for an optimization problem. Unfortunately the output file in .sol format doesn't contain the iterations data. The information available in the solution file is shown below. SCIP version…
Wilson Mendes
  • 139
  • 8
3
votes
1 answer

Multiple MILP solutions in ORTOOLS [python]

I am trying to use or-tools in Python to solve a mixed-integer linear program that has multiple optimal solutions. However, NextSolution() always returns False, so I cannot retrieve more than one solution. I understand that this function works…
David Haley
  • 31
  • 2
3
votes
1 answer

SCIP make install error - scipoptsuite-6.0.2

I want to use SCIP optimization suite 6.0.2 together with the Python interface PySCIPOpt, and to enable debugging. I work in Linux - Ubuntu 18.04LTS, without sudo privileges (I avoid using sudo because I want to do the same on a cluster, where I…
Avrech ben david
  • 45
  • 4
3
votes
0 answers

pyscipopt, nonlinear system of equations, code is working but slow doesn't scale

I have a system of equations to solve which goes like this: https://i.stack.imgur.com/FQY2g.jpg the left side of the equation is the sum, and the right side is the constraints. I have a system of N nonlinear equations with N variables. I tried…
Lionel Yelibi
  • 43
  • 6
3
votes
1 answer

Set MIP termination gap with PySCIPOpt

I cannot figure out how to set a MIP gap threshold such that the solver will terminate when the relative difference between the primal and dual solutions is within some value. I am using PySCIPOpt to interact with SCIP. I am sure there is a simple…
kenl
  • 195
  • 1
  • 7
3
votes
1 answer

Error when setting SCIP as solver with PYOMO

I am trying to solve a MILP problem set up in PYOMO whith SCIP as solver. I run the problem from within PyDev using the python ANACONDA interpreter. I can run and solve the problem with other solvers, namely CBC, GLPK, and IPOPT. However, it does…
sasap
  • 33
  • 1
  • 4
3
votes
1 answer

unexpected VARSYM in zimpl

I am getting an unexpected VARSYM in my Zimpl code. Here is a portion of my code: param T := 0.8; var S[Sensors] binary; minimize nb_sensors : sum < i > in Sensors : S[ i ]; subto fd: 1- prod in Sensors*Pipe : (1-ord(Proba[k,l],1,1) *…
Noureddine
  • 232
  • 2
  • 10
3
votes
2 answers

error of building google or-tools on win7

I would like to install google-or-tools (https://code.google.com/p/or-tools/) on win 7 so that I can call third party optimization solvers (scip http://scip.zib.de/ ) from vidsual studio 2013. I am new to the or-tools. I followed the instructions…
user3601704
  • 753
  • 1
  • 14
  • 46
1
2 3
…
27 28