Installation

SNOPT.jl needs two parts: the Julia package, installed with the package manager, and the SNOPT shared library, available from the SNOPT distributors. This page explains how to connect the two and how to check the result.

Requirements

• Julia 1.10 or later.
• A licensed SNOPT 7.7 shared library, libsnopt7, that includes the C interface from snopt-interface.

SNOPT.jl reads the iteration counts and the solve time from fixed positions in the SNOPT 7.7 workspace. With another SNOPT version, a solve can be correct while these values are wrong.

Install the package

using Pkg
Pkg.add("SNOPT")

To use the development version:

using Pkg
Pkg.develop(url = "https://github.com/EllissoideRotondo/SNOPT.jl")

The package loads without the SNOPT library. In that case SNOPT.has_snopt returns false, and each solve throws an error that explains how to make the library available.

Make the library available

The library file has a different name on each platform:

Set the environment variable SNOPTDIR to the directory that contains this file. Do this before you start Julia.

Linux and macOS (bash or zsh):

export SNOPTDIR=/path/to/snopt/lib

Windows (PowerShell):

$env:SNOPTDIR = "C:\path\to\snopt\lib"

SNOPT.jl looks for the library once, when you load the package. If you change SNOPTDIR later, restart Julia.

Some SNOPT licenses also need the variable SNOPT_LICENSE. Follow the instructions that come with your SNOPT distribution.

Search order

SNOPT.jl accepts the first library that it can load and that contains all the C functions it needs. It looks in these places, in this order:

1. The directory in SNOPTDIR. If SNOPTDIR is set but the library there cannot be used, SNOPT.jl shows a warning and continues.
2. The directories in LD_LIBRARY_PATH (Linux and macOS), DYLD_LIBRARY_PATH (macOS) or PATH (Windows).
3. The default locations of the system loader, for example /usr/lib on Linux.

If a file libiomp5 (the Intel OpenMP runtime library) is in the same directory as libsnopt7, SNOPT.jl also loads it. If that fails, SNOPT.jl continues without it.

Check the setup

This command prints the path of the library that SNOPT.jl found. If you installed SNOPT.jl in a project environment, add --project=/path/to/project after julia.

julia -e 'using SNOPT; @assert SNOPT.has_snopt(); println(SNOPT.libsnopt7)'

In PowerShell:

julia -e "using SNOPT; @assert SNOPT.has_snopt(); println(SNOPT.libsnopt7)"

Then solve the first problem in Getting started.

Platform support

Troubleshooting

Start with the values that SNOPT.jl sees:

using SNOPT

SNOPT.has_snopt()        # true if a usable library was found
SNOPT.libsnopt7          # path of that library, or ""
SNOPT.find_snopt_lib()   # repeat the search now

SNOPT.find_snopt_lib does not change SNOPT.libsnopt7. After you correct the setup, restart Julia.

has_snopt() returns false

• Make sure that SNOPTDIR is the directory that contains the library, not the path of the library file.
• Make sure that your user can read the file.
• If find_snopt_lib() also returns "", no directory in the search order contains a usable library.

The library exists but does not load

The system loader cannot load the library, or the library does not contain the C interface. On Linux, ldd /path/to/libsnopt7.so lists the shared libraries that are missing.

SNOPT.jl needs the C functions from snopt-interface, for example f_sninitx, f_snoptb and f_snkera. SNOPT.jl checks for all of them before it accepts a library. A library built only from the Fortran source does not contain these functions. Use a SNOPT distribution that includes the C interface, or build SNOPT again with snopt-interface.

Windows

SNOPT.jl needs a libsnopt7.dll built with MinGW, the GNU compiler for Windows. The library built with the Intel compiler for Visual Studio passes arguments in a different way and does not work with SNOPT.jl. If you only have a Linux library, use the Windows Subsystem for Linux (WSL).