ABS function not supported in problem type 'optim.pro​blemdef.Op​timization​Expression​'.

% %% initialise slots request, social valur, capacity %%

% %% decision variable type: alloted matrix,social value function, capacity required %%

clc

clear all

cap = 3

bigCAP = 5;

s_v = 2.5

basic_data = readmatrix('book1.xlsx')

a = max(basic_data(:,1));

slot = [1:a,100]

for i =1:length(basic_data)

request(i,basic_data(i,1)) = 1

s(i,:) = basic_data(i,3)

end

z = zeros(length(basic_data),1);

request(:,end+1)=z;

pair = [2,4,1];

size_p =size(pair);

size_r =size(request);

allot_prob = optimproblem;

decision_variable = optimvar('decision_variable',size_r(1),size_r(2),'Type','integer','LowerBound',0,'UpperBound',1)

e = optimvar('e',1,size_r(2),'Type','integer','LowerBound',0,'UpperBound',2)

y = optimvar('y',1,size_r(2),'Type','continuous','LowerBound',0)

% %% Calculate difference between requested and alloted slot%%

[I,J] = find(request > 0)

for i=1:size_r(1)

n(i) = (request(I(i),J(i)) - decision_variable(I(i),J(i)))

end

c = sum(n) %% x(i,a)* |t-t(m)| %%

%%----------------------------------------------------------------------------------%%

for i = 1:size_r(1)

value(i) = sum(abs(slot.*request(i,:) - slot.*decision_variable(i,:)))

value1 = sum(value)

end

%%----------------------------------------------------------------------------------%%

for i = 1:size_p(1) %% pairwise movement %%

pairwise (i) =sum(slot.*decision_variable(pair(i,2),:)) - sum(slot.*decision_variable(pair(i,1),:)) >= pair(i,3)

end

allot_prob.Constraints.pairwise = pairwise;

%%----------------------------------------------------------------------------------%%

for i=1:size_r(1) %% one slot per movement %%

move_const(i) =sum(decision_variable(i,:)) == 1;

end

allot_prob.Constraints.move_const = move_const;

%%----------------------------------------------------------------------------------%%

for i=1:size_r(2)-3; %% capacity constraint%%

cap_const(i)=sum(decision_variable(:,i))+ sum(decision_variable(:,i+1))+ sum(decision_variable(:,i+2))<= cap + e(i) + e(i+1) + e(i+2);

end

cap_const(size_r(2)-3) = sum(decision_variable(:,size_r(2)-3)) <= cap/3 + e(size_r(2)-3)

cap_const(size_r(2)-2) = sum(decision_variable(:,size_r(2)-2)) <= cap/3 + e(size_r(2)-2)

cap_const(size_r(2)-1) = sum(decision_variable(:,size_r(2)-1)) <= cap/3 + e(size_r(2)-1)

allot_prob.Constraints.cap_const = cap_const;

%%----------------------------------------------------------------------------------%%

for i=1:(size_r(2)-3); %% social value constraint%%

social_value(i)=sum(decision_variable(:,i).*s + decision_variable(:,i+1).*s + decision_variable(:,i+2).*s) + y(i) >= (cap + e(i))*s_v

end

allot_prob.Constraints.social_value = social_value;

%%----------------------------------------------------------------------------------%%

Y = sum(y)

E = sum(e)

cap_const(size_r(2))=sum(decision_variable(:,size_r(2)))<=bigCAP, %% rejected slot %%

allot_prob.Constraints.cap_const = cap_const

%%----------------------------------------------------------------------------------%%

allot_prob.Objective = -value1 + 1000*c + E + Y; %% objective function %%

showproblem(allot_prob)

[sol,fval] = solve(allot_prob);

%%----------------------------------------------------------------------------------%%

[J] = find(request)

[Y] = find(sol.decision_variable)

Answer 1

[Rajani Mishra]

The error encountered : 'optim.pro​blemdef.Op​timization​Expression​' is because of the abs function used in the code at the line : 'value(i) = sum(abs(slot.*request(i,:) - slot.*decision_variable(i,:)))'

abs() function is not supported on optimization variables and expressions. The code runs successfully without the use of abs function.

For list of operations supported please refer : https://www.mathworks.com/help/optim/ug/supported-operations-on-optimization-variables-expressions.html