Index exceeds matrix dimensions.

function []=diagonal()

n=41; ns=(n+1)/2; h=1/(n-1); nt=360;

x=(0:n-1)*h; y=x; p0=ones(n); tau=0.01;

for jt=1:nt

t(jt)=jt*tau;

pt = exp(-2 * t(jt) * x.' .* y);

end

tic

for jt=1:nt % Vaqt bo`yicha tsikl}

spmd

aa1(1)=0; bb1(1)=1;

a=1; c=1; b=2+2*h^2/tau;

for j=2:ns % Tenglamalar koeffitsientini parallel hisoblash

for i=2:n-1

ff=h^2*(-2*(2*t(jt)^2*(x(i)^2+y(j)^2)+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));

d=2*h^2/tau*p0(i,j)+(p0(i,j-1)-2*p0(i,j)+p0(i,j+1))+ff;

aa1(i)=c/(b-aa1(i-1)*a);

bb1(i)=(d+bb1(i-1)*a)/(b-aa1(i-1)*a);

end

p(n,j)=exp(-2*y(j)*t(jt));

for i=n-1:-1:1

p(i,j)=aa1(i)*p(i+1,j)+bb1(i);

end

end %j

for j=n-1:-1:ns-1 % Tenglamalar koeffitsientini parallel hisoblash

for i=2:n-1

ff=h^2*(-2*(2*t(jt)^2*(x(i)^2+y(j)^2)+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));

d=2*h^2/tau*p0(i,j)+(p0(i,j-1)-2*p0(i,j)+p0(i,j+1))+ff;

aa1(i)=c/(b-aa1(i-1)*a);

bb1(i)=(d+bb1(i-1)*a)/(b-aa1(i-1)*a);

end

p(n,j)=exp(-2*y(j)*t(jt));

for i=n-1:-1:1

p(i,j)=aa1(i)*p(i+1,j)+bb1(i);

end

end %j

for i=1:n

p(i,n)=(4.0*p(i,n-1)-p(i,n-2))/3;

p(i,1)=(4.0*p(i,2)-p(i,3))/3;

end

p0=p;

end

spmd

aa1(1)=0; bb1(1)=1;

a=1; c=1; b=2+2*h^2/tau;

for i=2:ns % Tenglamalar koeffitsientini parallel hisoblash

for j=2:n-1

ff=h^2*(-2*(2*t(jt)^2*(x(i)^2+y(j)^2)+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));

d=2*h^2/tau*p0(i,j)+(p0(i-1,j)-2*p0(i,j)+p0(i+1,j))+ff;

aa1(j)=c/(b-aa1(j-1)*a);

bb1(j)=(d+bb1(j-1)*a)/(b-aa1(j-1)*a);

end

p(i,n)=exp(-2*x(i)*t(jt));

for j=n-1:-1:1

p(i,j)=aa1(j)*p(i,j+1)+bb1(j);

end

end %i

for i=n-1:-1:ns-1 % Tenglamalar koeffitsientini parallel hisoblash

for j=2:n-1

ff=h^2*(-2*(2*t(jt)^2*(x(i)^2+y(j)^2)+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));

d=2*h^2/tau*p0(i,j)+(p0(i-1,j)-2*p0(i,j)+p0(i+1,j))+ff;

aa1(j)=c/(b-aa1(j-1)*a);

bb1(j)=(d+bb1(j-1)*a)/(b-aa1(j-1)*a);

end

p(i,n)=exp(-2*x(i)*t(jt));

for j=n-1:-1:1

p(i,j)=aa1(j)*p(i,j+1)+bb1(j);

end

end %i

for j=1:n

p(n,j)=(4.0*p(n-1,j)-p(n-2,j))/3;

p(1,j)=(4.0*p(2,j)-p(3,j))/3;

end

p0=p;

end

end % jt

toc

px = p0(21,:); pxt = pt(21,:);

x=0:h:1; y=0:h:1;

figure ('Position',[600 60 700 600]); %Natijalarni figuraga chiqarish oynasi: 750-eni, 650-boyi, 700-chapdan masofa, 75-yuqoridan masofa

subplot(3,2,1);

meshc(x,y,pt) %Uch o'lchovli 3D grafika

title('АНИК ЕЧИМ 3D ГРАФИГИ')

subplot(3,2,2);

meshc(x,y,p) %Uch o'lchovli 3D grafika

title('CОНЛИ ЕЧИМ 3D ГРАФИГИ')

subplot(3,2,3);

contour(x,y,pt,'ShowText','on','LineWidth',2); %kontur chizish

title('АНИК ЕЧИМ КОНТУР ГРАФИГИ')

subplot(3,2,4);

contour(x,y,p,'ShowText','on','LineWidth',2); %kontur chizish

title('CОНЛИ ЕЧИМ КОНТУР ГРАФИГИ')

subplot(3,2,5);

plot(x,px,x,pxt); %Ikki o'lchovli grafika

title('КЕСИМДА АНИК ВА CОНЛИ ЕЧИМ ЎЗГАРИШИ X БЎЙИЧА')

end

[Max Heimann]

What is your question?

[Shikhnazar Ismailov]

Error in program

px = p0(21,:);

Caused by:

Index exceeds matrix dimensions.

Answer 1

[Cris LaPierre]

the complete error is

Error using indexing

An invalid indexing request was made.

Caused by:

Index in position 1 exceeds array bounds. Index must not exceed 1.

Whe I run your code, I discover that, because your invoke spmd, the code is run in a parallel pool. The resulting value of p0 from that pool is 1x4 composite

p0 =

Worker 1: class = double, size = [41 41]

Worker 2: class = double, size = [41 41]

Worker 3: class = double, size = [41 41]

Worker 4: class = double, size = [41 41]

You would access the values using notation similar to

p01=p0{1};

px = p01(21,:)

Incidentally, all of your worker results are the same, which suggest to me this calculation is likely not one that is suitable for a parallel pool. It also runs much quicker without it, as you do not need to start up the pool.

n=41;              ns=(n+1)/2;    h=1/(n-1);    nt=360;
x=(0:n-1)*h;       y=x;           p0=ones(n);   tau=0.01;
for jt=1:nt
    t(jt)=jt*tau;
    pt = exp(-2 * t(jt) * x.' .* y);
end
tic
for jt=1:nt    % Vaqt bo`yicha tsikl}

    aa1(1)=0;   bb1(1)=1;
    a=1;        c=1;        b=2+2*h^2/tau;
    for j=2:ns     % Tenglamalar koeffitsientini parallel hisoblash
        for i=2:n-1
            ff=h^2*(-2*(2*t(jt)^2*(x(i)^2+y(j)^2)+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
            d=2*h^2/tau*p0(i,j)+(p0(i,j-1)-2*p0(i,j)+p0(i,j+1))+ff;
            aa1(i)=c/(b-aa1(i-1)*a);
            bb1(i)=(d+bb1(i-1)*a)/(b-aa1(i-1)*a);
        end
        p(n,j)=exp(-2*y(j)*t(jt));
        for i=n-1:-1:1
            p(i,j)=aa1(i)*p(i+1,j)+bb1(i);
        end
    end %j

    for j=n-1:-1:ns-1    % Tenglamalar koeffitsientini parallel hisoblash
        for i=2:n-1
            ff=h^2*(-2*(2*t(jt)^2*(x(i)^2+y(j)^2)+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
            d=2*h^2/tau*p0(i,j)+(p0(i,j-1)-2*p0(i,j)+p0(i,j+1))+ff;
            aa1(i)=c/(b-aa1(i-1)*a);
            bb1(i)=(d+bb1(i-1)*a)/(b-aa1(i-1)*a);
        end
        p(n,j)=exp(-2*y(j)*t(jt));
        for i=n-1:-1:1
            p(i,j)=aa1(i)*p(i+1,j)+bb1(i);
        end
    end %j

    for i=1:n
        p(i,n)=(4.0*p(i,n-1)-p(i,n-2))/3;
        p(i,1)=(4.0*p(i,2)-p(i,3))/3;
    end

    p0=p;
    aa1(1)=0;   bb1(1)=1;
    a=1;        c=1;        b=2+2*h^2/tau;
    for i=2:ns    % Tenglamalar koeffitsientini parallel hisoblash
        for j=2:n-1
            ff=h^2*(-2*(2*t(jt)^2*(x(i)^2+y(j)^2)+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
            d=2*h^2/tau*p0(i,j)+(p0(i-1,j)-2*p0(i,j)+p0(i+1,j))+ff;
            aa1(j)=c/(b-aa1(j-1)*a);
            bb1(j)=(d+bb1(j-1)*a)/(b-aa1(j-1)*a);
        end
        p(i,n)=exp(-2*x(i)*t(jt));
        for j=n-1:-1:1
            p(i,j)=aa1(j)*p(i,j+1)+bb1(j);
        end
    end  %i

    for i=n-1:-1:ns-1   % Tenglamalar koeffitsientini parallel hisoblash
        for j=2:n-1
            ff=h^2*(-2*(2*t(jt)^2*(x(i)^2+y(j)^2)+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
            d=2*h^2/tau*p0(i,j)+(p0(i-1,j)-2*p0(i,j)+p0(i+1,j))+ff;
            aa1(j)=c/(b-aa1(j-1)*a);
            bb1(j)=(d+bb1(j-1)*a)/(b-aa1(j-1)*a);
        end
        p(i,n)=exp(-2*x(i)*t(jt));
        for j=n-1:-1:1
            p(i,j)=aa1(j)*p(i,j+1)+bb1(j);
        end
    end %i

    for j=1:n
        p(n,j)=(4.0*p(n-1,j)-p(n-2,j))/3;
        p(1,j)=(4.0*p(2,j)-p(3,j))/3;
    end

    p0=p;
end % jt
toc

Elapsed time is 0.149321 seconds.

px  = p0(21,:);          pxt = pt(21,:);
x=0:h:1;            y=0:h:1;
figure ('Position',[600 60 700 600]); %Natijalarni figuraga chiqarish oynasi: 750-eni, 650-boyi, 700-chapdan masofa, 75-yuqoridan masofa
subplot(3,2,1);
meshc(x,y,pt) %Uch o'lchovli 3D grafika
title('АНИК ЕЧИМ 3D ГРАФИГИ')
subplot(3,2,2);
meshc(x,y,p) %Uch o'lchovli 3D grafika
title('CОНЛИ ЕЧИМ 3D ГРАФИГИ')
subplot(3,2,3);
contour(x,y,pt,'ShowText','on','LineWidth',2); %kontur chizish
title('АНИК ЕЧИМ КОНТУР ГРАФИГИ')
subplot(3,2,4);
contour(x,y,p,'ShowText','on','LineWidth',2); %kontur chizish
title('CОНЛИ ЕЧИМ КОНТУР ГРАФИГИ')
subplot(3,2,5);
plot(x,px,x,pxt); %Ikki o'lchovli grafika
title('КЕСИМДА АНИК ВА CОНЛИ ЕЧИМ ЎЗГАРИШИ X БЎЙИЧА')

[Shikhnazar Ismailov]

How can I use the program in parallel?

[Shikhnazar Ismailov]

If n=101 and nt=1080 the program slows down! It requires a parallel calculation!

[Cris LaPierre]

On my system, with n=101 and nt=1080, it took 4 seconds to run without spmd. On my system, anythign using spmd takes much more time, even for the simple example above.

I'm definitely not an expert on parallelizing code, but perhaps this example can help you.