Originally posted by: brown_rice

Hi,

In an iterative method, when I solve my LP, here what CPLEX reports. I was wondering what this means. 

Parallel mode: deterministic, using up to 4 threads for concurrent optimization.

Iteration log . . .
Iteration:     1   Scaled dual infeas =         94895.713491
Using devex.

Barrier solved model.
 

I am not sure which part of the log is unclear. It says that 4 threads were available to CPLEX and CPLEX used concurrenopt to solve the problem. The fastest algorithm to solve the problem was the barrier algorithm.

Originally posted by: brown_rice

In the first iterations, CPLEX was solving the LP with dual simplex and then I realized that it switched to barrier method. Then, I guess CPLEX decided which is the fastest way to solve. I was just wondering if I did change a setting without my intention. That's why just wanted to make sure.

Thanks,

CPLEX does not switch algorithm. It runs dual simplex and barrier concurrently. The first algorithm to finish stops the other and CPLEX uses the results from the winner. Since CPLEX cannot use logs of multiple algorithms at the same time, it always only shows the dual simplex node. This may then be truncated in case another algorithm than dual simplex solve the problem fastest.

See here for some more details.