PATHSolver.jl

A Julia interface to the PATH solver.

Build Statuscodecov

Installation

Install PATHSolver.jl as follows:

import Pkg; Pkg.add("PATHSolver")

By default, PATHSolver.jl will download a copy of the underlying PATH solver. To use a different version of PATH, see the Manual Installation section below.

License

Without a license, the PATH Solver can solve problem instances up to with up to 300 variables and 2000 non-zeros. For larger problems, this web page provides a temporary license that is valid for a year.

You can either store the license in the PATH_LICENSE_STRING environment variable, or you can use the PATHSolver.c_api_License_SetString function immediately after importing the PATHSolver package:

using PATHSolver
PATHSolver.c_api_License_SetString("<LICENSE STRING>")

where <LICENSE STRING> is replaced by the current license string.

Example usage

julia> using JuMP, PATHSolver

julia> M = [
           0  0 -1 -1
           0  0  1 -2
           1 -1  2 -2
           1  2 -2  4
       ]
4×4 Array{Int64,2}:
 0   0  -1  -1
 0   0   1  -2
 1  -1   2  -2
 1   2  -2   4

julia> q = [2, 2, -2, -6]
4-element Array{Int64,1}:
  2
  2
 -2
 -6

julia> model = Model(PATHSolver.Optimizer)
A JuMP Model
Feasibility problem with:
Variables: 0
Model mode: AUTOMATIC
CachingOptimizer state: EMPTY_OPTIMIZER
Solver name: Path 5.0.00

julia> set_optimizer_attribute(model, "output", "no")

julia> @variable(model, x[1:4] >= 0)
4-element Array{VariableRef,1}:
 x[1]
 x[2]
 x[3]
 x[4]

julia> @constraint(model, M * x .+ q ⟂ x)
[-x[3] - x[4] + 2, x[3] - 2 x[4] + 2, x[1] - x[2] + 2 x[3] - 2 x[4] - 2, x[1] + 2 x[2] - 2 x[3] + 4 x[4] - 6, x[1], x[2], x[3], x[4]] ∈ MOI.Complements(4)

julia> optimize!(model)
Reading options file /var/folders/bg/dzq_hhvx1dxgy6gb5510pxj80000gn/T/tmpiSsCRO
Read of options file complete.

Path 5.0.00 (Mon Aug 19 10:57:18 2019)
Written by Todd Munson, Steven Dirkse, Youngdae Kim, and Michael Ferris

julia> value.(x)
4-element Array{Float64,1}:
 2.8
 0.0
 0.7999999999999998
 1.2

julia> termination_status(model)
LOCALLY_SOLVED::TerminationStatusCode = 4

Factorization methods

By default, PATHSolver.jl will download the LUSOL shared library. To use LUSOL, set the following options:

model = Model(PATHSolver.Optimizer)
set_optimizer_attribute(model, "factorization_method", "blu_lusol")
set_optimizer_attribute(model, "factorization_library_name", PATHSolver.LUSOL_LIBRARY_PATH)

To use factorization_method umfpack you will need the umfpack shared lib that is available directly from the developers of that code for academic use.

Manual installation

By default PATHSolver.jl will download a copy of the libpath library. If you already have one installed and want to use that, set the PATH_JL_LOCATION environment variable to point to the libpath50.xx library, then run Pkg.build("PATHSolver").