[AMPL 15261] help BARON to find feasible solution

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SG
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[AMPL 15261] help BARON to find feasible solution

SG
Hi,

I defined the objetive function minimize 

z: X_Am_c + X_Am_g + X_Am_k;

while

# area
param Am_min := 0.5; # min  area [m2]
param Am_max := 20; # max  area [m2]
var X_Am_c >= Am_min, <= Am_max; #  area
var X_Am_g >= Am_min, <= Am_max; #  area
var X_Am_k >= Am_min, <= Am_max; #  area

When I run filter solver I get the optimal value of 

filterSQP (20020316): Optimal solution found, objective = 10.94671379
37 iterations (19 for feasibility)
Evals: obj = 26, constr = 44, grad = 27, Hes = 32
z = 10.9467
X_Am_c = 1.08342
X_Am_g = 5.00282
X_Am_k = 4.86047

Using BARON just gave me the following solution! 

===========================================================================
  Iteration    Open nodes         Time (s)    Lower bound      Upper bound
          1             1             0.12     1.50000         0.100000E+52
        458           291            39.20     1.50000         0.100000E+52
       1561           892            69.24     1.50000         0.100000E+52
       2265          1313           115.63     1.50000         0.100000E+52
       3026          1762           161.79     1.50000         0.100000E+52
       4081          2350           191.82     1.50000         0.100000E+52
       4787          2776           235.34     1.50000         0.100000E+52
       5009          2917           265.37     1.50000         0.100000E+52
       5590          3203           305.81     1.50000         0.100000E+52
       6083          3452           346.52     1.50000         0.100000E+52
       6274          3559           376.57     1.50000         0.100000E+52
       7281          4099           406.63     1.50000         0.100000E+52
       8127          4571           436.66     1.50000         0.100000E+52
       8430          4752           471.06     1.50000         0.100000E+52
       8655          4885           500.39     1.50000          30.0000    

                    *** Max. allowable time exceeded ***      

                   *** No feasible solution was found ***

 Wall clock time:                   500.00
 Total CPU time used:               500.39

 Total no. of BaR iterations:    8655
 Best solution found at node:      -3
 Max. no. of nodes in memory:    4885
 
 All done
===========================================================================
BARON 16.7.29 (2016.07.29): 8655 iterations, CPU time limit reached.
Objective 1e+51
z = 0
X_Am_c = 0
X_Am_g = 0
X_Am_k = 0

I used even the baron options as: # option baron_options 'outlev=1 maxtime=-1 maxiter=-1';

but nothing. 

And all the variables equal to ZERO. That's unbelievable as I limited bounds of variables directly affected the obj function but nothing happened!!

I am wondering if I can improve the rate of convergence? Or somehow trigger the solver to see the global optimum 

Thank you. 

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