How to sole the solve the error " Conversion to logical from sym is not possible" in my program?

Hi everyone.

I want to solve the following optimization problem, But my program has a error please help me if it is possible for you...

my optimization problem and loss function ..

And I writing the code of this program and try to solve that with YALMIP package...in my program K=E(ρ(z)) , c=1 , T=5 , z=randn and ρ is the loss function.thanks

my progra code is :

clc;

clear;

close all;

ab=[ 0.0181   -0.0041    0.0040    0.0373    0.0580    0.0009    0.0250   -0.0009    0.0205    0.0302 
    0.0290    0.0260    0.0260   -0.0234    0.0250   -0.0136   -0.0311   -0.0451    0.0576   -0.0288];

% I use a YALMIP package for solve this problem

T=5;

z=randn;

syms f(x) g(y) integer

f(x)=(1/6)*((x^2 - 1)^3 + 1);

g(y)=(1/6);

if abs(z)<=1
    K=mean(f(z));
else
    K=mean(g(z));
end

syms a b c d e l 

E =(( a*e + b*l -d )/c);

a=sdpvar(1,1);

% a b c d are the variable defined in package

b=sdpvar(1,1);

c=sdpvar(1,1);

d=sdpvar(1,1);

F=0;

for i=1:5

      E2=subs(E,[e,l],[ab(1,i),ab(2,i)]);

      if abs(E2)<=1;% my problem starts here

          F=F+f(E3);

      else

          F=F+g(E2);

      end

end

% The main template package in accordance with the instructions

f1=c;

co=[F==K*T];

co=co+[a+b==1];

options=sdpsettings('solver','BMIBNB');

sol=optimize(co,f1,options);

if sol.problem == 0

      solution = value(x)

else

      display('Hmm, something went wrong!');

      sol.info

      yalmiperror(sol.problem)

end

Answer 1

[Walter Roberson]

A = sdpvar(1,1);     % a b c d are the variable defined in package
B = sdpvar(1,1);
C = sdpvar(1,1);
D = sdpvar(1,1);

...

E2 = double( subs(E, {e, l, a, b, c, d}, {ab(1,i), ab(2,i), A, B, C, D}) );

Remember, when a formula has been defined with a symbol, and the symbol is later assigned a numeric value, then the formula does not gain the numeric value until you request to subs() it in. Just like if you have

X = 2
A = X + 1
X = 4

then A does not suddenly become 4+1,

sym X
A = X + 1
X = 4

then A does not suddenly become 4+1