Cannot find Cplex, GLPK, Gurobi, HiGHS, or any other solver

Describes what to do if an external solver is installed but not detected by idol_cl.

If idol reports that a solver cannot be found, it usually means the solver library is not located in a standard system directory, or its location is not known to idol.

Solver libraries are searched in directories in the following order:

1. A solver-specific environment variable (recommended)
2. Standard system installation directories
3. Default library names available in the system library path

• GLPK To help idol locate GLPK, you can set the environment variable IDOL_GLPK_PATH.

  This variable should point to the GLPK library file.

  Example:

  export IDOL_GLPK_PATH=/path/to/libglpk.so

  If this variable is not set, idol will automatically search common system locations, including:

  • /opt/homebrew/opt/glpk/lib/libglpk.dylib
  • /usr/local/opt/glpk/lib/libglpk.dylib
  • /opt/homebrew/lib/libglpk.dylib
  • /usr/local/lib/libglpk.dylib
  • /usr/lib/libglpk.so
  • /usr/lib64/libglpk.so
  • /usr/local/lib/libglpk.so
  • /usr/local/lib64/libglpk.so
  • /lib/x86_64-linux-gnu/libglpk.so
  • /usr/lib/x86_64-linux-gnu/libglpk.so
  • libglpk.dylib
  • libglpk.so

• Gurobi To help idol locate Gurobi, you can set the environment variable IDOL_GUROBI_PATH.

  This variable should point to the Gurobi library file.

  Example:

  IDOL_GUROBI_PATH=/Library/gurobi1300/macos_universal2/lib/libgurobi130.dylib

  If this variable is not set, idol will automatically search the folder indicated by GUROBI_HOME variable.

  This variable is normally configured automatically when installing Gurobi.

  Example:

  GUROBI_HOME=/Library/gurobi1300/macos_universal2

• HiGHS To help idol locate HiGHS, you can set the environment variable IDOL_HiGHS_PATH.

  This variable should point to the HiGHS library file.

  Example:

  export IDOL_HiGHS_PATH=/path/to/libhighs.so

  If this variable is not set, idol will automatically search common system locations, including:

  • /opt/homebrew/opt/highs/lib/libhighs.dylib
  • /usr/local/opt/highs/lib/libhighs.dylib
  • /opt/homebrew/lib/libhighs.dylib
  • /usr/local/lib/libhighs.dylib
  • /usr/lib/libhighs.so
  • /usr/lib64/libhighs.so
  • /usr/local/lib/libhighs.so
  • /usr/local/lib64/libhighs.so
  • /lib/x86_64-linux-gnu/libhighs.so
  • /usr/lib/x86_64-linux-gnu/libhighs.so
  • libhighs.dylib
  • libhighs.so

• MibS If you installed idol using a package manager (apt-get or brew), MibS should already be correctly configured. Try reinstalling idol.

  If you built idol from source, make sure that MibS support was enabled during configuration:

  • USE_MIBS=ON,
  • COIN_OR_DIR must point to your coin-or installation directory (dist/).

  If not, please refer to Build from source.

  Also ensure that the coin-or dist directory was not moved after installation.