Hi there,
I am new to GLPK and to LP solving in general
I created a model that is supposed to optimize the travel cost of technician
that visit clients to repair their security system
- I have a graph of nodes and edges representing possible paths with
their costs
- I have a qualification matrix to send a technician that has the
required qualifications at a client site
Out of this I create constraints using the OPTANO modeling tools = mainly I
create my variables, constraints and objective using OPTANO objects and it will
translate this into a GLPK problem and then runs it
I have a problem understanding GLPK behavior with my model when I get this
error message :
GLPK Simplex Optimizer, v4.65
5157 rows, 5980 columns, 892762 non-zeros
0: obj = 0.000000000e+000 inf = 2.300e+001 (23)
Perturbing LP to avoid stalling [199]...
Warning: basis matrix is ill-conditioned (cond = 1.13e+015)
Warning: basis matrix is ill-conditioned (cond = 1.45e+015)
Warning: basis matrix is ill-conditioned (cond = 1.48e+015)
Warning: basis matrix is ill-conditioned (cond = 2.2e+014)
Error: basis matrix is singular to working precision (cond = 1.54e+017)
I thought it could be numeric overflow so I added a divider to all my values in
the constraints and the objective function but it did not solve my problem
Q1 : what "matrix is ill-conditioned" means ? do I have any kind of
inconsistencies in my constraints ?
Q2 : what is this "working precision" ?
Q3 : what can be the source of this problem : my constraints ? my objective ?
Thank you for your help
Cheers
Christophe
Christophe Garcia
Resp Developpements Informatique
Stanley Security
3 chemin du Torey, 69340 Francheville, France
T +33 4 72 59 26 97 | F +33 4 72 59 26 79 | M +33 6 23 31 88 94
christophe.gar...@sbdinc.com |
www.stanleyblackanddecker.com<http://www.stanleyblackanddecker.com/>
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