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4. Primal to dual conversion example ( Enter your problem )
  1. Formulation and Rules
  2. Example-1
  3. Example-2
  4. Example-3
  5. Example-4
  6. Example-5
  7. Example-6
Other related methods
  1. Formulate linear programming model
  2. Graphical method
  3. Simplex method (BigM method)
  4. Two-Phase method
  5. Primal to dual conversion
  6. Dual simplex method
  7. Integer simplex method
  8. Branch and Bound method
  9. 0-1 Integer programming problem
  10. Revised Simplex method

6. Example-5
(Previous example)
6. Dual simplex method
(Next method)

7. Example-6





Find dual from primal conversion
MAX z = x1 - 2x2 + 3x3
subject to
-2x1 + x2 + 3x3 = 2
2x1 + 3x2 + 4x3 = 1
and x1,x2,x3 >= 0


Solution:
Primal is (Solution steps of Primal by Simplex method)

MAX `z_x``=``````x_1`` - ``2``x_2`` + ``3``x_3`
subject to
` - ``2``x_1`` + ````x_2`` + ``3``x_3`=`2`
```2``x_1`` + ``3``x_2`` + ``4``x_3`=`1`
and `x_1,x_2,x_3 >= 0; `


In primal, There are `3` variables and `2` constraints, so in dual there must be `3` constraints and `2` variables

In primal, The coefficient of objective function `c_1=1,c_2=-2,c_3=3` becomes right hand side constants in dual

In primal, The right hand side constants `b_1=2,b_2=1` becomes coefficient of objective function in dual

In primal, objective function is maximizing, so in dual objective function must be minimizing

Let `y1,y2` be the dual variables

Since `1^(st),2^(nd)` constraints in the primal are equalities, the corresponding dual variables `y_1,y_2` will be unrestricted in sign.

Dual is (Solution steps of Dual by Simplex method)

MIN `z_y``=````2``y_1`` + ````y_2`
subject to
` - ``2``y_1`` + ``2``y_2``1`
`````y_1`` + ``3``y_2``-2`
```3``y_1`` + ``4``y_2``3`
and ```y_1,y_2` unrestricted in sign



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6. Example-5
(Previous example)
6. Dual simplex method
(Next method)





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