[Scip] Interpretation of solution file from SCIP: missing variables and

[Ramón Casero Cañas]

Dear all,

So thanks to your help and the documentation, I have been able to
write my problem to a PIP file, call the SCIP binary from Matlab
(scip-3.0.2.linux.x86_64.gnu.opt.spx), solve the problem until it
finds 1 valid solution, write the solution to a file, and read it back
into Matlab.

I have variables

x1
y1
z1
...
x4574
y4574
z4574

both in the objective function and constraints.

SCIP runs for a while, finds a solution, and writes its to a file. It
seems that I have variables missing in the solution

solution status: solution limit reached
objective value:                    -760.711552889581
x1                                   0.44337718267988   (obj:0)
y1                                  -1.11537963003733   (obj:0)
z1                                  0.640066367478129   (obj:0)
x2                                  0.635593926577552   (obj:0)
y2                                  0.405953492189133   (obj:0)
z2                                   1.13206100660573   (obj:0)
...
x20                                 0.225420591151844   (obj:0)
y20                                  1.33025644597009   (obj:0)
z20                                  0.17304145468582   (obj:0)
y21                                  1.09858400598118   (obj:0)
x22                                 0.042773405539517   (obj:0)
y22                                  1.05348001958397   (obj:0)
y23                                 0.715794911501469   (obj:0)
...

Note how e.g. x21, z21 and z22 are missing here (and they are not
elsewhere in the file either). Is this expected behaviour?

In addition, the solutions file has at the end lines like:

quadobjvar                          -760.711552889581   (obj:1)
nlreform0                           0.820888812661168   (obj:0)
nlreform1                           0.777248902182625   (obj:0)
nlreform2                          -0.189610104867685   (obj:0)
nlreform3                         -0.0728986988897996   (obj:0)
...

What are those for? I did an online search, but could only find where
nlreform is coded in SCIP, not what it means.

Best regards,

Ramon.

-- 
Dr. Ramón Casero Cañas

Oxford e-Research Centre (OeRC)
University of Oxford
7 Keble Rd
Oxford OX1 3QG

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