# Linear program problem solving Dual and using SIMPLEX

• Mar 26th 2007, 09:20 PM
ruprotein
Linear program problem solving Dual and using SIMPLEX
i think i had to do tis wrong its taking me a ffreakin life time to solve, can any1 tell me how many interations they did for this problem.... and what kind of numbers there getting, i set

Find the dual of the following LP and then solve the dual using the simplex

max -x1 -2x2
s.t -3x1+x2<= -1
x1 -x2 <=1
-2x1+7x2<=6
9x1-4x2<=6
-5x1+2x2<=-3
7x1-3x2<=6
x1,x2>=0

here is the dual i got i dunno if u guys will ge tthe same
where w is the variable i introduced

min -w1+w2+6w3+6w4-3w5+6w6
s.t
-3w1+w2-2w9w4-5w5+7w6<=-1
w1-w2+7w3-4w4+2w5-3w6<=-2
w1,w2>=0

my slack variables are s and t

so applying simplex i get

max w1 - w2 - 6w3 - 6w6 +3w5 -6w6

subject to (s.t.)
-3w1+w2-2w9w4-5w5+7w6 + s = -1
w1-w2+7w3-4w4+2w5-3w6 + t = -2
w1,w2>=0

now therest is also taking me forever so i think im doion sumthin wrong
• Mar 27th 2007, 07:31 AM
JakeD
Quote:

Originally Posted by ruprotein
i think i had to do tis wrong its taking me a ffreakin life time to solve, can any1 tell me how many interations they did for this problem.... and what kind of numbers there getting, i set

Find the dual of the following LP and then solve the dual using the simplex

max -x1 -2x2
s.t -3x1+x2<= -1
x1 -x2 <=1
-2x1+7x2<=6
9x1-4x2<=6
-5x1+2x2<=-3
7x1-3x2<=6
x1,x2>=0

here is the dual i got i dunno if u guys will ge tthe same
where w is the variable i introduced

min -w1+w2+6w3+6w4-3w5+6w6
s.t
-3w1+w2-2w9w4-5w5+7w6<=-1
w1-w2+7w3-4w4+2w5-3w6<=-2
w1,w2>=0

my slack variables are s and t

so applying simplex i get

max w1 - w2 - 6w3 - 6w6 +3w5 -6w6

subject to (s.t.)
-3w1+w2-2w9w4-5w5+7w6 + s = -1
w1-w2+7w3-4w4+2w5-3w6 + t = -2
w1,w2>=0

now therest is also taking me forever so i think im doion sumthin wrong

Looks correct except that the inequalities are in the wrong direction for the dual so the slack variables have the wrong sign. The Simplex Java Applet will walk you through a solution.