Help me to run the code

2 views (last 30 days)
MINATI PATRA
MINATI PATRA on 29 Oct 2021
Commented: MINATI PATRA on 13 Nov 2021
% file modified by sujogya %dated 9.1.2021
% min z=x1-3x2+2x3 % max z'=-x1+3x2-2x3 % s.t. %3x1-x2+2x3<=7, %-2x1+4x2+0x3<=12, %-4x1+3x2+8x3<=10
NVar = 3; C = [-1 3 2]; CMat = [3 -1 2;-2 4 0;-4 3 8]; b = [7; 12; 10;];
s = eye(size(CMat,1)); A = [CMat s b]; cost = zeros(1,size(A,2)); cost(1:NVar) = C;
%% Constraint
BV = NVar+1:1:size(A,2)-1; zjcj = cost(BV)*A - cost;
%% print the Table
zcj = [zjcj;A]; simpletable = array2table(zcj);
simpletable.Properties.VariableNames(1:size(zcj,2)) = {'x_1','x_2','x_3','s_1','s_2','s_3','sol'}
if any(zjcj<0);
fprintf('the current solution is not optimal');
fprintf('\n--------------next iteration----------')
disp('old basic variable(BV)=')
else('optimal solution reached');
end
disp(BV);
%% find entering variable
zc = zjcj(1:end-1); [entercol,pvt_col] = min(zc);
fprintf('the most negative element in zj-cj row is %d corresponding to column%d\n',entercol,pvt_col)
fprintf('entering variable is %d\n',pvt_col);
%% finding leaving variable
sol = A(:,end)
column = A(:,pvt_col);
if all(column <= 0)
printf(' solution is unbdd');
for i = 1:size(column,1)
if column(i)>0
ratio(i) = sol(i)./column(i);
else
ratio(i) = inf
end
end
[MinRatio, pvt_row] = min(ratio);
fprintf('min ratio correspond to pivot row is %d\n',pvt_row);
fprintf('leaving variable %d\n',BV(pvt_row));
end
%% Finding the minimum
BV(pvt_row) = pvt_col;
disp('New basic variables(BV)=');
disp(BV);
%% Pivot key
pivot_key = A(pvt_row,pvt_col);
%%% update the table
A(pvt_row,:) = A(pvt_row,:)./pvt_key;
for i = 1:size(A,1)
if i ~= pvt_row
A(i,:) = A(i,:) - A(i,pvt_col).*A(pvt_row,:);
end
zjcj = zjcj-zjcj(pvt_col).*A(pvt_row,:);
end
%%% for printing purpose
zcj = [zjcj;A]; simptable = array2table(zcj);
simptable.properties.variable(1:size(zcj,2)) = {'x_1','x_2','x_3','s_1','s_2','s_3','sol'};
%%%% simplex method start
run = true
while run
if any(zjcj < 0);
fprintf(' the current solution is not optimal\n')
fprintf(' ----next iteration start----\n')
disp('the old basic variable (BV)=');
disp(BV);
%% print the optimal solution
BFS = zeros(1,size(A,2)); BFS(BV) = A(:,end); BFS(end) = sum(BFS.*cost);
current_BFS = array2table(BFS);
current_BFS.properties.variablenames(1:size(current_BFS,2)) = {'x_1','x_2','x_3','s_1','s_2','s_3','sol'};
else
run = false
fprintf('-------**********--------\n')
fprintf('the solution is optimal\n')
disp('optimal solution')
end
end

Accepted Answer

Walter Roberson
Walter Roberson on 30 Oct 2021
if all(column <= 0)
if that is false, then
[MinRatio, pvt_row] = min(ratio);
that is not executed, and then
BV(pvt_row) = pvt_col;
pvt_row is not defined -- because you only assign to it if all(column <= 0)
  3 Comments
Walter Roberson
Walter Roberson on 11 Nov 2021
Maybe V(pvt_row) = pvt_col; should be inside the if
MINATI PATRA
MINATI PATRA on 13 Nov 2021
@ Thank you Walter, It is done.

Sign in to comment.

More Answers (1)

Sulaymon Eshkabilov
Sulaymon Eshkabilov on 30 Oct 2021
Some of the assigned variables don't get their values from the second [if .. end] and [for end] operations, e.g.: pvt_row
Thus, its default value has to be assigned. Moreover, one variable name is misspelled: pivot_key vs. pivt_key
There is no need to rename simptable variable names, since it is already done.
In addition, to rename table variable names (e.g. current_BFS), it is better to use renamevars().

Categories

Find more on Particle & Nuclear Physics in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!