我试图通过使用OPL将其编写为线性程序并使用CPLEX Studio解决它来解决网络流问题 . CPLEX Studio需要26分钟才能解决问题 . 但是, Engine Log
表示 Network time = 0.21 sec
:
CPXPARAM_LPMethod 3
Tried aggregator 1 time.
LP Presolve eliminated 914361 rows and 916674 columns.
Aggregator did 5 substitutions.
Reduced LP has 4629 rows, 457853 columns, and 913392 nonzeros.
Presolve time = 1.28 sec. (955.67 ticks)
Extracted network with 4630 nodes and 457853 arcs.
Extraction time = 0.04 sec. (22.54 ticks)
Iteration log . . .
Iteration: 0 Infeasibility = 3444.000000 (-1.21856e+06)
...
Iteration: 50000 Objective = -1158876.510000
Network - Optimal: Objective = -1.1643204900e+06
Network time = 0.21 sec. (53.14 ticks) Iterations = 54799 (15500)
我不完全确定我是否正确阅读了日志 .
是否意味着预解决(或其他开销)耗时26分钟消除行/列等,而实际的网络解决只花了0.2秒?
如果是这样,绕过预定会更快? (如果有必要,我怎么能绕过预先解决?)
1 回答
您应该查看“探查器”选项卡,以了解时间花在哪里
技术说明:http://www-01.ibm.com/support/docview.wss?uid=swg21401402
OPL CPLEX论坛:https://www.ibm.com/developerworks/community/forums/html/forum?id=11111111-0000-0000-0000-000000002053