Income and risk of linear programming example investment

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Get the inflection point $a$ Value run to find the corresponding variable value

clear;clc;
a=0;% Investment risk 
hold on
while a<0.05
    c=[0.05 0.27 0.19 0.185 0.185];% Coefficient matrix of objective function 
    A=[zeros(4,1),diag([0.025 0.015 0.055 0.026])];% Coefficient matrix of inequality 
    % hold 1*4 Column vectors and 4*4 The matrix of , The diagonal to diag The elements in 
    b=a*ones(1,4);% Generate all 1 The column vector , Multiply all elements by a
    %b Whether it is a row vector or a column vector does not affect the result 
    Aeq=[1 1.01 1.02 1.045 1.065];% The coefficient matrix in the left end of the equation 
    beq=1;% The value at the right end of the equation 
    lb=zeros(1,5);% Variable x Lower bound of 
    %lb Whether it is a row vector or a column vector does not affect the result 
    [x, Q]=linprog(-c,A,b,Aeq,beq,lb);% Remember to take -c
    plot(a,-Q,'*r');% -Q Is the final value 
    a=a+0.001;
end
xlabel('a'),ylabel('Q')