Originally posted by: EPED_Nicholas_Drake

I am having trouble creating solution pools with the MATlab interface for cplex. I am having trouble understanding what parameters I need to set to catch all possible solutions.

My matlab file looks as follows

%%%%%%%%%%%%%%%%
function LCP_final
try
clc
m= 1 -1; 0 -1;
q = -2, 4';
xv = sym('x1');
lm = length(m);
yv = sym(zeros(1, lm))';
zv = sym(zeros(1, lm))';
for k=1:lm
yv(k) = sym(sprintf('x%d', k+1));
zv(k) = sym(sprintf('x%d', k+lm+1));
end
A = m*yv+xv*q+zv;-(m*yv+xv*q); yv-zv;
for i=1:length(A)
A(i,:)=sort(A(i,:));
end
xx = cat(1,xv ,yv,zv);
Aineq = zeros(numel(A),numel(xx));
for j=1:length(A)
for i=1:length(xx)
y=xx(i);
c,t=coeffs(A(j),y);
if (length(t)<2)
else
insert=c(2);
Aineq(j,i)=insert;
end
end
end
bineq=zeros(length(Aineq),1);
for temp=1:(length(zv))
bineq(temp,1)=1;
end
f = -1 -1 -1 0 0';
Aeq=[];
beq=[];
ub= inf; 1; 1; 1; 1;
lb=0; 0;0;0;0;
ctype= 'CCCBB';
options = cplexoptimset, populate;
options.Diagnostics = 'on';
x, fval, exitflag, output = cplexmilp (f, Aineq, bineq, Aeq, beq,...
[ ], [ ], ], lb, ub, ctype, [, options);
fprintf ('\nSolution status = %s \n', output.cplexstatusstring);
fprintf ('Solution value = %f \n', fval);
disp ('Values =');
disp (x);
catch m
disp (m.message);
end
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: EPED_Nicholas_Drake

I forgot to add that I receive the following solution:
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: EPED_Nicholas_Drake

I forgot to add I do get a solution:

Tried aggregator 2 times.
MIP Presolve eliminated 2 rows and 1 columns.
MIP Presolve modified 2 coefficients.
Aggregator did 1 substitutions.
Reduced MIP has 3 rows, 3 columns, and 7 nonzeros.
Reduced MIP has 1 binaries, 0 generals, 0 SOSs, and 0 indicators.
Presolve time =    0.00 sec.
MIP emphasis: balance optimality and feasibility.
MIP search method: dynamic search.
Parallel mode: deterministic, using up to 2 threads.
Root relaxation solution time =    0.00 sec.
 
        Nodes                                         Cuts/ 
   Node  Left     Objective  IInf  Best Integer     Best Node    ItCnt     Gap
 
*     0+    0                           -0.7500                      1     --- 
*     0     0      integral     0       -1.8333       -1.8333        1    0.00%
 
Root node processing (before b&c):
  Real time             =    0.02
Parallel b&c, 2 threads:
  Real time             =    0.00
  Sync time (average)   =    0.00
  Wait time (average)   =    0.00
                          -------
Total (root+branch&cut) =    0.02 sec.
Solution status = integer optimal solution 
Solution value = -1.833333 
Values =
    0.1667
    1.0000
    0.6667
    1.0000
    1.0000

The problem I have is that I know this is not the global optimal solution, first values values should be .25 for the optimal for this problem.

Any help would be great.
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: John Cui

How about the objective value?

I think it is possible that the decision variables are different with same objective value.
John Cui
#CPLEXOptimizers
#DecisionOptimization