Initializing help system before first use

problem.getprimalray

problem.getprimalray

Purpose
Retrieves a primal ray (primal unbounded direction) for the current problem, if the problem is found to be unbounded.
Synopsis
problem.getprimalray (ray)
Argument
ray 
Array of length problem.attributes.cols to hold the ray. May be None if not required.
Example
The following code tries to retrieve a primal ray: 
if not p.hasprimalray ():
    print ("Could not retrieve a primal ray")
else:
    ray = []
    p.getprimalray (ray)
    print ("primal ray:", ray)
Further information
1. It is possible to retrieve a primal ray only when, after solving an LP problem, the final status ( LPSTATUS) is xpress.lp_unbounded.
2. Primal rays are not post-solved. If the problem is in a presolved state, the primal ray that is returned will be for the presolved problem. If the problem was solved with presolve on and has been restored to the original state (the default behavior), this function will not be able to return a ray. To ensure that a primal ray can be obtained, it is recommended to solve a problem with presolve turned off ( PRESOLVE = 0).
Related topics
problem.getdualray.

Parent Topic Reference Manual

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