Extractin LP model from AMPL

Question

I have a very big and complicated LP model in AMPL . I need to extract Ax<= b format from my LP (ie), I need to extract all my data in form of matrix A , b , and all variables to be concatenate into a large vector x .

How can I do that?

Answer 1

In case you are familiar with coding for example in Java you could use an open source library/solver called GLPK.

In there you can read your .mod file and extract your data from the A and b Matrix. I am sure that the commercial software such as CPLEX/ Gurobi can also do that (also academic license available). Here you can find the user guide for GLPK: http://www.chiark.greenend.org.uk/doc/glpk-doc/glpk.pdf

Look for the following:

• glp get mat row — retrieve row of the constraint matrix

perhaps this could help.