GAMS/PYOMO allows users to solve GAMS models using solvers within the PYOMO modeling system. The GAMS/PYOMO link comes free with any GAMS system. Users must have a licensed PYOMO system installed and have the PYOMO executable in their path.
To run GAMS/PYOMO, just specify the solver as
pyomo. For example, if we wish to solve the trnsport.gms model, we would run
>> gams trnsport.gms lp=pyomo
For other GAMS solvers, options can be passed on via solver option files. GAMS/PYOMO specific options are described in the section GAMS/PYOMO Options.
By default, GAMS/PYOMO tries to map the status from the Pyomo run into the GAMS solve- and model status.
GAMS external equations and extrinsic functions cannot be used with GAMS/PYOMO.
GAMS searches for an PYOMO executable using the following hierarchy:
- Via the options
RunPyomowithin a GAMS/PYOMO solver option file.
pyomopath.txtfile located in the GAMS system directory specifying the path of the PYOMO executable.
- The system path.
For example, GAMS will first search for the PYOMO executable within the
pyomo.opt file, if specified. If not found, it will search within the GAMS system directory for a file called
pyomopath.txt specifying the PYOMO directory. If
pyomopath.txt is still not found GAMS will try the system path.
If no PYOMO executable is found, the user will see a message similar to
PYOMO Link 24.5.1 r50798 Released Jun 23, 2015 VS8 x86 32bit/MS Windows --- Using Pyomo solver bonmin --- No PyomoPath option or "pyomopath.txt" file found --- System PATH will be used
There may also be an output indicating that PYOMO was not found, either because it was not installed or because it was not found in the system path.
|DotMod||Pyomo input file name|
Option specifier is used to specify desired PYOMO options within the PYOMO modeling system. For example, if a user wishes to run PYOMO/CBC with the options
threads=4 scaling=off then the user creates a file called
pyomo.opt with the entry
option "thread=4 scaling=off";