The MOSEK Python optimizer API manual Version 7.0 (Revision 141)

Optimizer API for Python - Documentation - Mosek Optimizer API for Python - Documentation - Mosek

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190 CHAPTER 15. SENSITIVITY ANALYSIS Supply Demand 400 Plant 1 1 2 Store 1 800 Store 2 100 1 1200 Plant 2 5 Store 3 500 1000 Plant 3 2 1 2 Store 4 500 Figure 15.2: Supply, demand and cost of transportation.

15.4. SENSITIVITY ANALYSIS FOR LINEAR PROBLEMS 191 Basis type Con. β 1 β 2 σ 1 σ 2 1 −300.00 0.00 3.00 3.00 2 −700.00 +∞ 0.00 0.00 3 −500.00 0.00 3.00 3.00 4 −0.00 500.00 4.00 4.00 5 −0.00 300.00 5.00 5.00 6 −0.00 700.00 5.00 5.00 7 −500.00 700.00 2.00 2.00 Var. β 1 β 2 σ 1 σ 2 x 11 −∞ 300.00 0.00 0.00 x 12 −∞ 100.00 0.00 0.00 x 23 −∞ 0.00 0.00 0.00 x 24 −∞ 500.00 0.00 0.00 x 31 −∞ 500.00 0.00 0.00 x 33 −∞ 500.00 0.00 0.00 x 34 −0.000000 500.00 2.00 2.00 Optimal partition type Con. β 1 β 2 σ 1 σ 2 1 −300.00 500.00 3.00 1.00 2 −700.00 +∞ −0.00 −0.00 3 −500.00 500.00 3.00 1.00 4 −500.00 500.00 2.00 4.00 5 −100.00 300.00 3.00 5.00 6 −500.00 700.00 3.00 5.00 7 −500.00 700.00 2.00 2.00 Var. β 1 β 2 σ 1 σ 2 x 11 −∞ 300.00 0.00 0.00 x 12 −∞ 100.00 0.00 0.00 x 23 −∞ 500.00 0.00 2.00 x 24 −∞ 500.00 0.00 0.00 x 31 −∞ 500.00 0.00 0.00 x 33 −∞ 500.00 0.00 0.00 x 34 −∞ 500.00 0.00 2.00 Table 15.1: Ranges and shadow prices related to bounds on constraints and variables. Left: Results for the basis type sensitivity analysis. Right: Results for the optimal partition type sensitivity analysis. x 11 + x 12 ≤ 400, x 23 + x 24 ≤ 1200, x 31 + x 33 + x 34 ≤ 1000, x 11 + x 31 = 800, x 12 = 100, x 23 + x 33 = 500, x 24 + x 34 = 500, x 11 , x 12 , x 23 , x 24 , x 31 , x 33 , x 34 ≥ 0. (15.3) The basis type and the optimal partition type sensitivity results for the transportation problem are shown in Table 15.1 and 15.2 respectively. Examining the results from the optimal partition type sensitivity analysis we see that for constraint number 1 we have σ 1 ≠ σ 2 and β 1 ≠ β 2 . Therefore, we have a left linearity interval of [−300, 0] and a right interval of [0, 500]. The corresponding left and right shadow prices are 3 and 1 respectively. This implies that if the upper bound on constraint 1 increases by β ∈ [0, β 1 ] = [0, 500] then the optimal objective value will decrease by the value σ 2 β = 1β. Correspondingly, if the upper bound on constraint 1 is decreased by

15.4. SENSITIVITY ANALYSIS FOR LINEAR PROBLEMS 191<br />

Basis type<br />

Con. β 1 β 2 σ 1 σ 2<br />

1 −300.00 0.00 3.00 3.00<br />

2 −700.00 +∞ 0.00 0.00<br />

3 −500.00 0.00 3.00 3.00<br />

4 −0.00 500.00 4.00 4.00<br />

5 −0.00 300.00 5.00 5.00<br />

6 −0.00 700.00 5.00 5.00<br />

7 −500.00 700.00 2.00 2.00<br />

Var. β 1 β 2 σ 1 σ 2<br />

x 11 −∞ 300.00 0.00 0.00<br />

x 12 −∞ 100.00 0.00 0.00<br />

x 23 −∞ 0.00 0.00 0.00<br />

x 24 −∞ 500.00 0.00 0.00<br />

x 31 −∞ 500.00 0.00 0.00<br />

x 33 −∞ 500.00 0.00 0.00<br />

x 34 −0.000000 500.00 2.00 2.00<br />

Optimal partition type<br />

Con. β 1 β 2 σ 1 σ 2<br />

1 −300.00 500.00 3.00 1.00<br />

2 −700.00 +∞ −0.00 −0.00<br />

3 −500.00 500.00 3.00 1.00<br />

4 −500.00 500.00 2.00 4.00<br />

5 −100.00 300.00 3.00 5.00<br />

6 −500.00 700.00 3.00 5.00<br />

7 −500.00 700.00 2.00 2.00<br />

Var. β 1 β 2 σ 1 σ 2<br />

x 11 −∞ 300.00 0.00 0.00<br />

x 12 −∞ 100.00 0.00 0.00<br />

x 23 −∞ 500.00 0.00 2.00<br />

x 24 −∞ 500.00 0.00 0.00<br />

x 31 −∞ 500.00 0.00 0.00<br />

x 33 −∞ 500.00 0.00 0.00<br />

x 34 −∞ 500.00 0.00 2.00<br />

Table 15.1: Ranges and shadow prices related to bounds on constraints and variables. Left: Results<br />

for the basis type sensitivity analysis. Right: Results for the optimal partition type sensitivity analysis.<br />

x 11 + x 12 ≤ 400,<br />

x 23 + x 24 ≤ 1200,<br />

x 31 + x 33 + x 34 ≤ 1000,<br />

x 11 + x 31 = 800,<br />

x 12 = 100,<br />

x 23 + x 33 = 500,<br />

x 24 + x 34 = 500,<br />

x 11 , x 12 , x 23 , x 24 , x 31 , x 33 , x 34 ≥ 0.<br />

(15.3)<br />

<strong>The</strong> basis type and the optimal partition type sensitivity results for the transportation problem are<br />

shown in Table 15.1 and 15.2 respectively. Examining the results from the optimal partition type<br />

sensitivity analysis we see that for constraint number 1 we have σ 1 ≠ σ 2 and β 1 ≠ β 2 . <strong>The</strong>refore, we<br />

have a left linearity interval of [−300, 0] and a right interval of [0, 500]. <strong>The</strong> corresponding left and<br />

right shadow prices are 3 and 1 respectively. This implies that if the upper bound on constraint 1<br />

increases by<br />

β ∈ [0, β 1 ] = [0, 500]<br />

then the optimal objective value will decrease by the value<br />

σ 2 β = 1β.<br />

Correspondingly, if the upper bound on constraint 1 is decreased by

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