Hello everyone,

I am solving a problem with Lingo in which the values of basic variables are not zero. I cannot understand what it means.

Here is the model and the solution:

MAX = 25.83 * Xa + 28 * Xb + 28.5 * Xc + 29.33 * Xd + 84.17 * Xe;
0.25 * Xa + 0.17 * Xb + 0.25 * Xc <= 80;
0.12 * Xb + 0.12 * Xc + 0.38 * Xd + Xe <=40;
0.33* Xa + 0.17 * Xb + 0.22 * Xc + 0.25 * Xd + 0.05 * Xe<= 120;
0.1* Xa + 0.25 * Xb + 0.17 * Xc + 0.1 * Xd + 0.07 * Xe<= 80;
Xa<=120;
Xb<=100;
Xc<=100;
Xd<=50;
Xe<=30;
@GIN(Xa);
@GIN(Xb);
@GIN(Xc);
@GIN(Xd);
@GIN(Xe);

Global optimal solution found.
Objective value: 10096.32
Objective bound: 10096.32
Infeasibilities: 0.000000
Extended solver steps: 0
Total solver iterations: 0


Variable Value Reduced Cost
XA 120.0000 -25.83000
XB 100.0000 -28.00000
XC 100.0000 -28.50000
XD 0.000000 -29.33000
XE 16.00000 -84.17000

Row Slack or Surplus Dual Price
1 10096.32 1.000000
2 8.000000 0.000000
3 0.000000 0.000000
4 40.60000 0.000000
5 24.88000 0.000000
6 0.000000 0.000000
7 0.000000 0.000000
8 0.000000 0.000000
9 50.00000 0.000000
10 14.00000 0.000000

I would highly appreciate it if anyone can help me.

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On Tuesday, October 11, 2016 at 3:32:12 AM UTC-4, Z. My wrote:

Hello everyone,

I am solving a problem with Lingo in which the values of basic variables are not zero. I cannot understand what it means.
...

Since you are declaring the variables as general integer, they are not really basic, and there is no reason to expect their reduced costs to be zero.

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