Question

我通过IDE（5.5.2.0）传递给lp_solve的一个简单问题

/* Objective function */
max: +r1 +r2;

/* Constraints */
R1: +r1 +r2 <= 4;
R2: +r1 -2 b1 = 0;
R3: +r2 -3 b2 = 0;

/* Variable bounds */
b1 <= 1;
b2 <= 1;

/* Integer definitions */
int b1,b2;

这个问题的显而易见的解决方案是3. SCIP以及CBC给出3作为答案但不是lp_solve。我得到2.解算器中是否存在重大错误？

提前感谢。

Answer 1

我与关心lpsolve软件的开发人员小组有过联系。该错误将在下一版本的lpsolve中修复。

Answer 2

当我尝试它时，我得到3作为Obj函数的最佳值。

Model name:  'LPSolver' - run #1
Objective:   Maximize(R0)

SUBMITTED
Model size:        3 constraints,       4 variables,            6 non-zeros.
Sets:                                   0 GUB,                  0 SOS.

Using DUAL simplex for phase 1 and PRIMAL simplex for phase 2.
The primal and dual simplex pricing strategy set to 'Devex'.

Relaxed solution                   4 after          4 iter is B&B base.

Feasible solution                  2 after          6 iter,         3 nodes (gap 40.0%)

Optimal solution                   2 after          7 iter,         4 nodes (gap 40.0%).
Excellent numeric accuracy ||*|| = 0

MEMO: lp_solve version 5.5.2.0 for 32 bit OS, with 64 bit REAL variables.
In the total iteration count 7, 1 (14.3%) were bound flips.
There were 2 refactorizations, 0 triggered by time and 0 by density.
... on average 3.0 major pivots per refactorization.
The largest [LUSOL v2.2.1.0] fact(B) had 8 NZ entries, 1.0x largest basis.
The maximum B&B level was 3, 0.8x MIP order, 3 at the optimal solution.
The constraint matrix inf-norm is 3, with a dynamic range of 3.
Time to load data was 0.001 seconds, presolve used 0.017 seconds,
... 0.007 seconds in simplex solver, in total 0.025 seconds.

lp_solve中的戏剧性错误？

2 个答案: