Why I am i getting a negative value for the spread when i restricted it have positive values.?I would be glad if anyone could help.

clear all
clc

IN=[-0.04844752  0.041968141  -0.044564664;
-0.304020248  0.131284505  0.472041681;
-0.074829705  -0.049999997  -0.094350919;
0.28895241  0.390694469  0.416666657;
-0.098011374  0.012270158  -0.067317739;
-0.175849974  -0.160909101  -0.174713209;
-0.141403094  -0.004999995  -0.098300003;
-0.210274339  -0.191784486  -0.109999985
]

OUT=[-0.148966655;
0.281067416;
-0.154999971;
0.360221535;
-0.120833755;
-0.18519102;
-0.136289001;
-0.184634596 ]

h=0.2
p=1-h

NEWIN=[ones(size(IN,1),1) IN]

num_NEWIN=size(NEWIN,2)

D=zeros(num_NEWIN,num_NEWIN)

E=(-1).*eye(num_NEWIN,num_NEWIN)

B=zeros(num_NEWIN,1)

A=[-NEWIN -p*abs(NEWIN); NEWIN -p*abs(NEWIN); D E]
b=[-OUT; OUT; B]

v1=sum(abs(NEWIN(:,1)))
v2=sum(abs(NEWIN(:,2)))
v3=sum(abs(NEWIN(:,3)))
v4=sum(abs(NEWIN(:,4)))

f=[zeros(num_NEWIN,1);v1;v2;v3;v4]
%f=[zeros(num_NEWIN,1);ones(num_NEWIN,1)]

x=linprog(f,A,b)
Center_coeff= x(1:4,1)
spread_coeff= x(5:8,1)

[Matt J]

Not me:

>> spread_coeff>=0

ans =

    4×1 logical array

     1
     1
     1
     1

Answer 1

[Constantino Carlos Reyes-Aldasoro]

Just ran your code and had this:

spread_coeff =

      0.0452
           0
           0
           0

No negatives

[Honey Adams]

for some values of h.. it gives me negatively.I have defined bounds for the problem.lb and ub.It worked.