Trying to solve piece-wise model over range of x

When I run the attached code I am getting the error: "Subscripted assignment dimension mismatch." I am trying to move forward piece-wise (H) over a range (x)...

TK=283;

iv=2;

Rg=8;

A=7.1e-12;

B=1.1e-7;

th=349e-6;

r=0.05;

R=0.1;

l=0.8;

for x=1:999;

SWU=2;

Qr(x)=10;

Qs(x)=Qr(x)*SWU;

S1(x)=0;

S5(x)=30;

D=14.5E-10;

Ur(x)=Qr(x)/(3.14*r^2);

Us(x)=Qs(x)/(3.14*(R^2-r^2));

Dhs=4*3.14*(R^2-r^2)/(2*3.14*(R+r));

kr(x)=1.62*Ur(x)^(1/3)*D^(2/3)/l^(1/3)/(2*r)^(1/3);

ks(x)=1.62*Us(x)^(1/3)*D^(2/3)/l^(1/3)/(Dhs)^(1/3);

dr(x)=D/kr(x);

ds(x)=D/ks(x);

    dSideal(1,x)=S5(x)-S1(x);

    dOideal(x)=(10^(-2)*dSideal(1,x)/58.44)*iv*Rg*TK;

    dP(x)=0.001*x*dOideal(x);

        for n=1:1:20000;

    dOn(n,x)=(10^(-2)*dSideal(n,x)/58.44)*iv*Rg*TK;

    Jwn(n,x)=A*(dOn(n,x)-dP(x))*10^5;

    dSn(n,x)=(S5(x)*exp(-Jwn(n,x)*ds(x)/D)-S1(x)*exp((th+dr(x))*Jwn(n,x)
/D))/(1+B/Jwn(n,x)*(exp((th+dr(x))*Jwn(n,x)/D)-exp(-Jwn(n,x)*ds(x)/D)));

    if ((dSideal(n,x)-dSn(n,x))>0.000001);

        dSideal(n+1,x)=dSideal(n,x)-0.01;

    else

        break

    end

        end

dO(x)=dOn(n,x);

Jw(x)=Jwn(n,x);

dS(x)=dSideal(n,x);

E(x)=dP(x)*Jw(x)*10^5;

betaS(x)=B*dSideal(n,x)/Jwn(n,x);

S1(x);

S2(x)=(S1(x)+betaS(x))*exp(Jw(x)*dr(x)/D)-betaS(x);

S3(x)=(S1(x)+betaS(x))*exp(Jw(x)*(th+dr(x))/D)-betaS(x);

S4a(x)=dSideal(n,x)+S3(x);

S4b(x)=(S5(x)+betaS(x))*exp(-Jw(x)*ds(x)/D)-betaS(x);

S5(x);

end

N=100;

Adesign=1500000;

Ai=Adesign/N;

for x=1:999;

%VALUES AT PIECE i=1

Qri(1,x)=Qr(x);

Qsi(1,x)=Qs(x);

S1i(1,x)=S1(x);

S5i(1,x)=S5(x);

dOi(1,x)=dO(x);

Jwi(1,x)=Jw(x);

dSi(1,x)=dS(x);

Ei(1,x)=E(x);

dST(1,x)=B*dS(x)*Ai;

dWR(1,x)=Jw(x)*Ai;

Ar(1,x)=0;

Po(1,x)=0;

%VALUES AT PIECE i=2

Qri(2,x)=Qri(1,x)-dWR(1,x);

Qsi(2,x)=dWR(1,x)+Qsi(1,x);

S1i(2,x)=(S1i(1,x)*Qri(1,x)/Qri(2,x))+(dST(1,x)/Qri(2,x));

S5i(2,x)=(Qsi(1,x)*S5i(1,x)/Qsi(2,x))-(dST(1,x)/Qsi(2,x));

Ar(2,x)=Ai;

Po(2,x)=E(x)*Ai;

Qr(x)=Qri(2,x);

Qs(x)=Qsi(2,x);

S1(x)=S1i(2,x);

S5(x)=S5i(2,x);

end

%SOLVE OVER RANGE OF H, FOR PARAMETERS REDEFINED BASED ON i=2

for x=1:999;

    for H=1:200;

Ur(x)=Qr(x)/(3.14*r^2);

Us(x)=Qs(x)/(3.14*(R^2-r^2));

Dhs=4*3.14*(R^2-r^2)/(2*3.14*(R+r));

kr(x)=1.62*Ur(x)^(1/3)*D^(2/3)/l^(1/3)/(2*r)^(1/3);

ks(x)=1.62*Us(x)^(1/3)*D^(2/3)/l^(1/3)/(Dhs)^(1/3);

dr(x)=D/kr(x);

ds(x)=D/ks(x);

    dSideal(1,x)=S5(x)-S1(x);

    dOideal(x)=(10^(-2)*dSideal(1,x)/58.44)*iv*Rg*TK;

    dP(x)=0.001*x*dOideal(x);

       for n=1:1:20000;

    dOn(n,x)=(10^(-2)*dSideal(n,x)/58.44)*iv*Rg*TK;

    Jwn(n,x)=A*(dOn(n,H,x)-dP(x))*10^5;

    dSn(n,x)=(S5(H,x)*exp(-Jwn(n,x)*ds(x)/D)-S1*exp((th+dr(x))*Jwn(n,x)/D))/(1+B/Jwn(n,x)*(exp((th+dr(x))*Jwn(n,x)/D)-exp(-Jwn(n,x)*ds(x)/D)));

    if ((dSideal(n,x)-dSn(n,x))>0.000001);

        dSideal(n+1,x)=dSideal(n,x)-0.01;

    else

        break

    end

        end

dO(x)=dOn(n,x);

Jw(x)=Jwn(n,x);

dS(x)=dSideal(n,x);

E(x)=dP(H,x)*Jw(x)*10^5;

betaS(x)=B*dSideal(n,x)/Jwn(n,x);

S1(x);

S2(x)=(S1(x)+betaS(x))*exp(Jw(x)*dr(x)/D)-betaS(x);

S3(x)=(S1(x)+betaS(x))*exp(Jw(x)*(th+dr(x))/D)-betaS(x);

S4a(x)=dSideal(n,x)+S3(x);

S4b(x)=(S5(x)+betaS(x))*exp(-Jw(x)*ds(x)/D)-betaS(x);

S5(x);

%VALUES AT PIECE i=H+1

dOi(H+1,x)=dO(x);

Jwi(H+1,x)=Jw(x);

dSi(H+1,x)=S4a(x)-S3(x);

Ei(H+1,x)=E(x);

dST(H+1,x)=B*dSi(H+1,x)*Ai;

dWR(H+1,x)=Jwi(H+1,x)*Ai;

%VALUES AT PIECE i=H+2

Qri(H+2,x)=Qri(H+1,x)-dWR(H+1,x);

Qsi(H+2,x)=dWR(H+1,x)+Qsi(H+1,x);

S1i(H+2,x)=(S1i(H+1,x)*Qri(H+1,x)/Qri(H+2,x))+(dST(H+1,x)/Qri(H+2,x));

S5i(H+2,x)=(Qsi(H+1,x)*S5i(H+1,x)/Qsi(H+2,x))-(dST(H+1,x)/Qsi(H+2,x));

Ar(H+2)=(H+1)*Ai;

Po(H+2,x)=Ei(H+1,x)*Ai+Po(H+1,x);

Qr(x)=Qri(H+2,x);

Qs(x)=Qsi(H+2,x);

S1(x)=S1i(H+2,x);

S5(x)=S5i(H+2,x);

if Ar(H+2)>Adesign;

    break

end

end

end