LQ command (Linear–quadratic regulator) with another reference

we have this system by its state representation :

the formulation of the quardatic command is described by the following equations:

exemple :

we would like to apply the quardatic command so that the output y(k) = x1(k) follows a certain reference.

For reference = 5 , this is the code :

clear, clc
Ac=[0 1;0 0]; Bc=[0;1]; Cc=[1 0]; Dc=0;
[A,B,C,D]=c2dm(Ac,Bc,Cc,Dc,0.1)   %Converting to discrete mode
N=600;
ref=5;       %The reference
Q=[1 2;2 1] ; R=0.1;
P=Q;
x_ref=[ref;0];
for k=N:-1:0
    F=R+B'*P*B;               %Equation 1
    K=inv(F)*B'*P*A;          %Equation 2
    M=P-P*B*inv(F)*B'*P;      %Equation 3
    P=A'*M*A+Q;               %Equation 4
end
u=0 ; x=[0;0];
for i=1:N
    x=A*x+B*u;
    u=-K*(x-x_ref);          %Equation 5
    y(i)=C*x;
end
plot(1:N,ref*ones(1,N),'r',1:N,y)

with this program I get this figure:

it is requested to make the same program so as to follow a new reference in the following form instead of the step reference "5" :

Refernece to follow :

someone would solve this problem?

Thank you in advance