How to do solve Riccati differential equation backward

I am having problem. I want to solve Riccati differential equation backward for time varying system. I try to follow the examples, and I wrote a code, but the result was strange and I have no idea about it, please help me.

    close all; clear all; clc

        Tspan = 1.7:-0.001:0; 

        v = openfig('acc.fig')   ;
        H = findobj(v,'type','line');
        nn = get (H, 'ydata');
        mm = get(H, 'xdata');

        q = openfig('angle.fig')   ;
        Q = findobj(q,'type','line');
        qq = get (Q, 'ydata');
        vv = get(Q, 'xdata');          

       %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% this is to find final condition  
        I = 0.0200;
        L = 0.325;
        g = 9.81;           
        m = 0.9847;
        C = 0.0076;
        Ibar = I + m*L*L;

        AA=[0 0 1 0; 0 0 0 1;0 0 0 0; 0 m*g*L/Ibar 0 -C/Ibar]; %%at the final condition, angle=0;
        BB = [0 0 1 -m*L/Ibar];
        BB = BB';

        Z = [0.0002 0 0 0; 0 0 0 0;0 0 0.0005 0; 0 0 0 0];  %%Z is Q and RR is R
        N = zeros(4,1);
        RR = 0.002;
        [K,S,e] = LQR(AA,BB,Z,RR,N) ;   %%S is the final condition, Backward integration use final condition

    [T P] = ode45(@(t,p) MM_mRiccati22(t,p,mm,nn,qq,vv), Tspan,S );

    plot(T,P)
    title('NUMERIC RICCATI-MATRIX SOLUTION');
    xlabel('time t');
    ylabel('solution y');

      %%Calculate K

    [m n] = size(P);
    PP = mat2cell(P, ones(m,1), n);
    fh_reshape = @(x)reshape(x,size(Z));
    PP = cellfun(fh_reshape,PP,'UniformOutput',false);

    num_t = length(Tspan);

    K1=zeros(1,1701);
    K2=zeros(1,1701);
    K3=zeros(1,1701);
    K4=zeros(1,1701);

    for i=1:num_t

        PPP = cell2mat(PP(i));  %---- P(t)

        angle = spline(vv,qq,Tspan(i)); 
        angle=angle*180/pi;
        b41 = -m*L*cos(angle)/Ibar;
        b = [0; 0; 1; b41];     %---- b(t)
        KK = -inv(RR)*b'*PPP;
        K1(i) =  KK(1);
        K2(i) =  KK(2);
        K3(i) =  KK(3);
        K4(i) =  KK(4);

    end 

figure(2)  
plot(Tspan,K1,'k', Tspan,K2, 'r', Tspan,K3, 'g', Tspan,K4,'b')
hleg = legend('K1','K2','K3','K4');

%%%%%%%%%%%%%%%%%%%%%%%%%%%%% the Riccati function

    I = 0.0200;
    L = 0.325;
    g = 9.81;           
    m = 0.9847;
    C = 0.0076;
    Ibar = I + m*L*L;

    Q=[0.0002 0 0 0; 0 0 0 0;0 0 0.0005 0; 0 0 0 0];
    R=0.002;

    angle = spline(vv,qq,t); 
    angle=angle*180/pi;
    acc = spline(mm,nn,t); 

    a42 = (m*g*L*cos(angle) + m*L*sin(angle)*acc)/Ibar;
    a44 = -C/Ibar;

    b41 = -m*L*cos(angle)/Ibar;

    A = [0 0 1 0; 0 0 0 1; 0 0 0 0; 0 a42 0 a44];
    b = [0; 0; 1; b41];

    p = reshape(p, size(A));      %Convert from "n^2"-by-1 to "n"-by-"n"
    dpdt = p*b*(R^-1)*b'*p  -p*A  -A'*p  -Q; %Determine derivative
    dpdt = dpdt(:);    %converting dxdt into a column vector as expected by ode45

    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  end

[upinderjeet]

did u find the answer...i am also trying to find the way to solve the riccati equation backward in time..if you have found the way please share it with me