Re: [Help-glpk] memory usage seems very high

[Andrew Makhorin]

To my previous message.

I used the following command to convert big.mod to big.lp:

glpsol --check -m big.mod --wcpxlp big.lp

and then run big.lp:

glpsol --cpxlp big.lp

GLPSOL: GLPK LP/MIP Solver 4.39
Reading problem data from `big.lp'...
92 rows, 5256 columns, 84142 non-zeros
23656 lines were read
Original LP has 92 rows, 5256 columns, 84142 non-zeros
Presolved LP has 82 rows, 5256 columns, 77163 non-zeros
Scaling...
 A: min|aij| =  1.000e+00  max|aij| =  1.600e+02  ratio =  1.600e+02
GM: min|aij| =  4.952e-01  max|aij| =  2.019e+00  ratio =  4.077e+00
EQ: min|aij| =  2.471e-01  max|aij| =  1.000e+00  ratio =  4.048e+00
Constructing initial basis...
Size of triangular part = 82
      0: obj =   0.000000000e+00  infeas =  5.657e+00 (0)
*    47: obj =   1.410800000e+00  infeas =  0.000e+00 (0)
*    74: obj =   5.761951817e-17  infeas =  8.327e-17 (0)
OPTIMAL SOLUTION FOUND
Time used:   0.5 secs
Memory used: 9.2 Mb (9607184 bytes)

The same, but with the LP presolver disabled:

glpsol --cpxlp big.lp --nopresol

GLPSOL: GLPK LP/MIP Solver 4.39
Reading problem data from `big.lp'...
92 rows, 5256 columns, 84142 non-zeros
23656 lines were read
Scaling...
 A: min|aij| =  1.000e+00  max|aij| =  1.600e+02  ratio =  1.600e+02
GM: min|aij| =  4.952e-01  max|aij| =  2.019e+00  ratio =  4.077e+00
EQ: min|aij| =  2.471e-01  max|aij| =  1.000e+00  ratio =  4.048e+00
Constructing initial basis...
Size of triangular part = 92
      0: obj =   0.000000000e+00  infeas =  5.657e+00 (0)
*    48: obj =   1.410800000e+00  infeas =  0.000e+00 (0)
*    70: obj =  -1.182847658e-16  infeas =  1.861e-16 (0)
OPTIMAL SOLUTION FOUND
Time used:   0.2 secs
Memory used: 5.6 Mb (5843231 bytes)