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<div class="moz-cite-prefix">Jackson,<br>
<br>
It looks as if you are running a series of interior point solves.
The interior point code is not as well tested as simplex and there
may be memory leaks which might cause problem.<br>
<br>
If you can send me driver (and data if possible) I may be able to
see what happens.<br>
<br>
Looking at statistics, it may be much faster to solve dual of
problem.<br>
<br>
John Forrest<br>
<br>
On 25/07/16 22:34, Jackson Gorham wrote:<br>
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<div>Hello! My name is Jackson Gorham, and I've been using the
Clp solver to solve many linear programs which are relevant to
my research. Recently, I been trying to solve some LPs and
unfortunately Clp has been segfault'ing on me. When I run the
program with its most verbose logging option, I see the
following on stdout:</div>
<div><br>
</div>
<div>
<div>[Solving optimization program]</div>
<div>Clp0051I Range of diagonal values is 1e+12 to
0.00074793108</div>
<div>Clp0054I 241 variables killed this iteration</div>
<div>Clp0058I Steps - primal 0.99429773 ,dual 0.99516802 , mu
1.4472757e-15</div>
<div>Clp0035I 13 Primal 153.81162 Dual 153.81162
Complementarity 6.736505e-10 - 17621 fixed, rank 127312</div>
<div>Clp0036I Feasible - objective gap 1.6454072e-09</div>
<div>Clp0042I Optimal</div>
<div>Clp0046I At end primal/dual infeasibilities 0/0,
complementarity gap 0, objective 153.81162</div>
<div>Clp0033I Barrier took 92.20 seconds (total 92.32)</div>
<div>Clp0033I Crossover took 0.00 seconds (total 92.32)</div>
<div>Coin0511I After Postsolve, objective 153.81162,
infeasibilities - dual 0 (0), primal 0 (0)</div>
<div>Clp0032I Optimal objective 153.8116218 - 26 iterations
time 92.332, Presolve 0.14</div>
<div>Coin0513I 1924 rows dropped after presolve pass 1</div>
<div>Coin0506I Presolve 409606 (-1924) rows, 49995 (-15)
columns and 1356796 (-11544) elements</div>
<div>Clp0033I Presolve took 0.32 seconds (total 0.32)</div>
<div>Clp0022I Absolute values of scaled rhs range from
0.005501532 to 7.9713658, minimum gap 1e+100</div>
<div>Clp0020I Absolute values of scaled objective range from
1.6232495e-09 to 0.002555952</div>
<span class="gmail-im">Clp0021I Absolute values of scaled
bounds range from 1 to 1, minimum gap 2</span>
<div>6.83568e+08 elements in sparse Cholesky, flop count
3.77274e+14</div>
</div>
<div><br>
</div>
<div>which after hanging for a while is followed by this getting
printed to stderr:</div>
<div><br>
</div>
<div>
<div>signal (11): Segmentation fault</div>
<div>_ZN15ClpCholeskyBase9factorizeEPKdPi at
/home/jgorham/.julia/v0.4/Cbc/deps/usr/lib/libClp.so
(unknown line)</div>
<div>_ZN21ClpPredictorCorrector14createSolutionEv at
/home/jgorham/.julia/v0.4/Cbc/deps/usr/lib/libClp.so
(unknown line)</div>
<div>_ZN21ClpPredictorCorrector5solveEv at
/home/jgorham/.julia/v0.4/Cbc/deps/usr/lib/libClp.so
(unknown line)</div>
<div>_ZN10ClpSimplex12initialSolveER8ClpSolve at
/home/jgorham/.julia/v0.4/Cbc/deps/usr/lib/libClp.so
(unknown line)</div>
<div>initial_solve_with_options at
/home/jgorham/.julia/v0.4/Clp/src/ClpCInterface.jl:190</div>
<div>optimize! at
/home/jgorham/.julia/v0.4/Clp/src/ClpSolverInterface.jl:183</div>
<div>jlcall_optimize!_22590 at (unknown line)</div>
<div>jl_apply at /dev/shm/julia-0.4.0/src/gf.c:1711</div>
<div>solve at
/home/jgorham/.julia/v0.4/JuMP/src/solvers.jl:138</div>
<div>julia_solve_22484 at (unknown line)</div>
<div>jl_apply at /dev/shm/julia-0.4.0/src/gf.c:1711</div>
<div>affine_graph_discrepancy at util.jl:155</div>
<div>...</div>
<div>...</div>
<div>srun: error: sh-26-33: task 0: Segmentation fault</div>
</div>
<div><br>
</div>
<div>I suspect this is due to the fact that my constraint matrix
is badly conditioned... is that correct? If so, is there
anything I can do to improve the preconditioning and/or get
around this? Let me know if I can provide any other
information that might be useful here.</div>
<div><br>
</div>
<div>Thanks!</div>
<div>~jackson</div>
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