What does these two block in mppt represent?

Hi everyone, from the mppt, these two blocks (1; 2 // https://imgur.com/a/jKNRoFE ) what their function according to the code.

function D=DutyRatio(V,I)
Dmax=0.95;
Dmin=0;
Dinit=0.95;
deltaD=0.0001;
persistent Vold Pold Dold;
dataType='double';
if isempty(Vold)
    Vold=0;
    Pold=0;
    Dold=0;
end
P=V*I;
dV=V-Vold;
dP=P-Pold;
if dP ~=0
    if dP<0
        if dV<0
            D= Dold - deltaD;
        else
            D= Dold+deltaD;
        end
    else
        if dV<0
            D= Dold+deltaD;
        else
            D=Dold-deltaD;
        end
    end
else D=Dold;
end
if D>=Dmax || D<=Dmin
    D=Dold;
end
Dold=D;
Vold=V;
Pold=P;

Answer 1

[Dr. Pemendra Kumar Pardhi]

Hi noble, Fist block represent to unit delay and second block is reapitive sequence generator.

The mppt block provides an appropriate duty cycle for dc-dc convert. The duty is compared with Reapitive sequence generator to provide pwm signal.