I am debugging the code I plan to use to generate cplex-format input files. I
am comparing my generated files to my "gold standard" which is a MathProg
model. I provide the MathProg model to glpsol and write out a cplex
translation to compare against my directly-generated cplex file. I am at the
point where I can't do much more debugging through text-parsing tools (sed,
awk, etc.). I would love to see a list of row names that glpk finds after the
presolve. Here is why:
Output from my directly generated cplex file:
...
lpx_read_cpxlp: 504148 rows, 299500 columns, 1096954 non-zeros
lpx_read_cpxlp: 299500 integer columns, all of which are binary
lpx_read_cpxlp: 1128550 lines were read
glp_simplex: original LP has 504148 rows, 299500 columns, 1096954 non-zeros
glp_simplex: presolved LP has 504148 rows, 299500 columns, 1096954 non-zeros
lpx_adv_basis: size of triangular part = 504148
0: objval = 0.000000000e+00 infeas = 1.000000000e+00 (0)
...
And here is the output from my reference model:
...
lpx_read_cpxlp: 547545 rows, 302843 columns, 1418415 non-zeros
lpx_read_cpxlp: 302843 integer columns, all of which are binary
lpx_read_cpxlp: 1851799 lines were read
glp_simplex: original LP has 547545 rows, 302843 columns, 1418415 non-zeros
glp_simplex: presolved LP has 504162 rows, 299500 columns, 1097272 non-zeros
lpx_adv_basis: size of triangular part = 504162
0: objval = 0.000000000e+00 infeas = 1.000000000e+00 (0)
...
So for my directly generated model I am trying to do my own "presolving" (in a
sense) by avoiding generation of trivial rows/cols. You can see that I am
producing 14 too few rows (504162 - 504148) in my directly generated cplex
file. Oh, how I'd love to know the names of those rows. Any thoughts on how
to tease those out? I am fine using the API. It seems that the presolver is
too much of a "black box" to get at via the API? Ideally before the phase I
simplex takes over but after the presolver, I'd like to dump that column name
info. Will I have to hack into the source to do this? Any suggestions
appreciated. I can provide more info if it's helpful.
Thanks in advance,
Joey
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