Engineering Optimization: Theory and Practice, Fourth Edition

(Martin Jones) #1
4.8 Quadratic Programming 229

Noting that
∑n

r= 1

x(r^1 )yr(^2 )=^13 ( 10834 )+^13 ( 10837 )+^13 ( 10837 )=^13

Eq. (4.71) can be used to find

{x(i^2 )} =










xi(^1 )y(i^2 )
∑^3
r= 1

x(r^1 )yr(^2 )










= 3










34
324
37
324
37
324










=








34
108
37
108
37
108








Set the new iteration number ask=k+ 1 =2 and go to step 2. The procedure
is to be continued until convergence is achieved.

Notes:
1.AlthoughX(^2 )=Y(^2 )in this example, they need not be, in general, equal to
one another.
2.The value off atX(^2 )is

f(X(^2 ))= 2 ( 10834 )+ 10837 − 10837 =^1727 < f (X(^1 ))=^1827

4.8 Quadratic Programming


Aquadratic programming problem can be stated as

Minimizef (X)=CTX+^12 XTDX (4.72)

subject to

AX≤B (4.73)

X≥ 0 (4.74)

where

X=










x 1
x 2
..
.
xn










, C=










c 1
c 2
..
.
cn










, B=










b 1
b 2
..
.
bm










,

D=






d 11 d 12 · · ·d 1 n
d 21 d 22 · · ·d 2 n
..
.
dn 1 dn 2 · · ·dnn






, and A=






a 11 a 12 · · · a 1 n
a 21 a 22 · · · a 2 n
..
.
am 1 am 2 · · ·amn






In Eq. (4.72) the term XTDX / 2 represents the quadratic part of the objective
function withDbeing a symmetric positive-definite matrix. IfD= 0 , the problem
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