How to convert to a parallel program?

4 views (last 30 days)
Shixnazar Ismailov
Shixnazar Ismailov on 17 Sep 2021
Edited: Jan on 24 Feb 2022
n=41;
h=1/(n-1);
nt=40;
x(1)=0; y(1)=0;
for i=2:n
x(i)=x(i-1)+h;
y(i)=y(i-1)+h;
end
for j=1:n
for i=2:n
p0(i,j)=1;
end
end
tic
tau=0.01;
for jt=1:nt % Vaqt bo`yicha tsikl}
t(jt)=jt*tau;
for j=1:n
for i=1:n
pt(i,j)=exp(-2*x(i)*y(j)*t(jt));
end
end
% k+0.s cloy
for j=2:21 % Tenglamalar koeffitsientini hisoblash
for i=2:n-1
a(i)=1;
c(i)=1;
b(i)=2+2*h*h/tau;
ff=h*h*(-2*(2*t(jt)*t(jt)*(x(i)*x(i)+y(j)*y(j))+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
d(i)=2*h*h/tau*p0(i,j)+(p0(i,j-1)-2*p0(i,j)+p0(i,j+1))+ff;
end
%Pragonka
aa1(1)=0; bb1(1)=1;
for i=2:n-1
aa1(i)=c(i)/(b(i)-aa1(i-1)*a(i));
bb1(i)=(d(i)+bb1(i-1)*a(i))/(b(i)-aa1(i-1)*a(i));
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=40:-1:22 % Tenglamalar koeffitsientini hisoblash
for i=2:n-1
a(i)=1;
c(i)=1;
b(i)=2+2*h*h/tau;
ff=h*h*(-2*(2*t(jt)*t(jt)*(x(i)*x(i)+y(j)*y(j))+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
d(i)=2*h*h/tau*p0(i,j)+(p0(i,j-1)-2*p0(i,j)+p0(i,j+1))+ff;
end
%Pragonka
aa1(1)=0; bb1(1)=1;
for i=2:n-1
aa1(i)=c(i)/(b(i)-aa1(i-1)*a(i));
bb1(i)=(d(i)+bb1(i-1)*a(i))/(b(i)-aa1(i-1)*a(i));
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
for j=1:n
for i=1:n
p0(i,j)=p(i,j);
end
end
% k+1 sloy
for i=2:21 % Tenglamalar koeffitsientini hisoblash }
for j=2:n-1
a(j)=1;
c(j)=1;
b(j)=2+2*h*h/tau;
ff=h*h*(-2*(2*t(jt)*t(jt)*(x(i)*x(i)+y(j)*y(j))+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
d(j)=2*h*h/tau*p0(i,j)+(p0(i-1,j)-2*p0(i,j)+p0(i+1,j))+ff;
end
%Pragonka
aa1(1)=0; bb1(1)=1;
for j=2:n-1
aa1(j)=c(j)/(b(j)-aa1(j-1)*a(j));
bb1(j)=(d(j)+bb1(j-1)*a(j))/(b(j)-aa1(j-1)*a(j));
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=40:-1:22 % Tenglamalar koeffitsientini hisoblash }
for j=2:n-1
a(j)=1;
c(j)=1;
b(j)=2+2*h*h/tau;
ff=h*h*(-2*(2*t(jt)*t(jt)*(x(i)*x(i)+y(j)*y(j))+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
d(j)=2*h*h/tau*p0(i,j)+(p0(i-1,j)-2*p0(i,j)+p0(i+1,j))+ff;
end
%Pragonka
aa1(1)=0; bb1(1)=1;
for j=2:n-1
aa1(j)=c(j)/(b(j)-aa1(j-1)*a(j));
bb1(j)=(d(j)+bb1(j-1)*a(j))/(b(j)-aa1(j-1)*a(j));
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
for i=1:n
for j=1:n
p0(i,j)=p(i,j);
end
end
end % jt
toc
for i=1:n
for j=1:n
b(j)=(p(i,j)-pt(i,j));
max=b(j);
end
end
for j=1:n
px(j)=p(21,j);
pxt(j)=pt(21,j);
end
t
p
pt
b
max
  4 Comments
Jan
Jan on 17 Sep 2021
Edited: Jan on 24 Feb 2022
Please start with improving the readability: ctrl-a ctrl-i. This automatic identation needs two keyboard activities only, but the code is much clearer.
Shixnazar Ismailov
Shixnazar Ismailov on 17 Sep 2021
n=41;
h=1/(n-1);
nt=40;
x(1)=0; y(1)=0;
for i=2:n
x(i)=x(i-1)+h;
y(i)=y(i-1)+h;
end
for j=1:n
for i=2:n
p0(i,j)=1;
end
end
tic
tau=0.01;
for jt=1:nt % Vaqt bo`yicha tsikl}
t(jt)=jt*tau;
for j=1:n
for i=1:n
pt(i,j)=exp(-2*x(i)*y(j)*t(jt));
end
end
% k+0.s cloy
for j=2:21 % Tenglamalar koeffitsientini hisoblash
for i=2:n-1
a(i)=1;
c(i)=1;
b(i)=2+2*h*h/tau;
ff=h*h*(-2*(2*t(jt)*t(jt)*(x(i)*x(i)+y(j)*y(j))+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
d(i)=2*h*h/tau*p0(i,j)+(p0(i,j-1)-2*p0(i,j)+p0(i,j+1))+ff;
end
%Pragonka
aa1(1)=0; bb1(1)=1;
for i=2:n-1
aa1(i)=c(i)/(b(i)-aa1(i-1)*a(i));
bb1(i)=(d(i)+bb1(i-1)*a(i))/(b(i)-aa1(i-1)*a(i));
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=40:-1:22 % Tenglamalar koeffitsientini hisoblash
for i=2:n-1
a(i)=1;
c(i)=1;
b(i)=2+2*h*h/tau;
ff=h*h*(-2*(2*t(jt)*t(jt)*(x(i)*x(i)+y(j)*y(j))+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
d(i)=2*h*h/tau*p0(i,j)+(p0(i,j-1)-2*p0(i,j)+p0(i,j+1))+ff;
end
%Pragonka
aa1(1)=0; bb1(1)=1;
for i=2:n-1
aa1(i)=c(i)/(b(i)-aa1(i-1)*a(i));
bb1(i)=(d(i)+bb1(i-1)*a(i))/(b(i)-aa1(i-1)*a(i));
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
for j=1:n
for i=1:n
p0(i,j)=p(i,j);
end
end
% k+1 sloy
for i=2:21 % Tenglamalar koeffitsientini hisoblash }
for j=2:n-1
a(j)=1;
c(j)=1;
b(j)=2+2*h*h/tau;
ff=h*h*(-2*(2*t(jt)*t(jt)*(x(i)*x(i)+y(j)*y(j))+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
d(j)=2*h*h/tau*p0(i,j)+(p0(i-1,j)-2*p0(i,j)+p0(i+1,j))+ff;
end
%Pragonka
aa1(1)=0; bb1(1)=1;
for j=2:n-1
aa1(j)=c(j)/(b(j)-aa1(j-1)*a(j));
bb1(j)=(d(j)+bb1(j-1)*a(j))/(b(j)-aa1(j-1)*a(j));
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=40:-1:22 % Tenglamalar koeffitsientini hisoblash }
for j=2:n-1
a(j)=1;
c(j)=1;
b(j)=2+2*h*h/tau;
ff=h*h*(-2*(2*t(jt)*t(jt)*(x(i)*x(i)+y(j)*y(j))+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
d(j)=2*h*h/tau*p0(i,j)+(p0(i-1,j)-2*p0(i,j)+p0(i+1,j))+ff;
end
%Pragonka
aa1(1)=0; bb1(1)=1;
for j=2:n-1
aa1(j)=c(j)/(b(j)-aa1(j-1)*a(j));
bb1(j)=(d(j)+bb1(j-1)*a(j))/(b(j)-aa1(j-1)*a(j));
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
for i=1:n
for j=1:n
p0(i,j)=p(i,j);
end
end
end % jt
toc
for i=1:n
for j=1:n
b(j)=(p(i,j)-pt(i,j));
max=b(j);
end
end
for j=1:n
px(j)=p(21,j);
pxt(j)=pt(21,j);
end
t
p
pt
b
max

Sign in to comment.

Accepted Answer

Jan
Jan on 17 Sep 2021
Pre-allocation is essential. Do not let array grow iteratively, but create them with the final size:
n = 41;
h = 1 / (n-1);
nt = 40;
% x(1) = 0;
% y(1) = 0;
% Better:
x = zeros(1, n); % Pre-allocation
y = zeros(1, n);
for i = 2:n
x(i) = x(i - 1) + h;
y(i) = y(i - 1) + h;
end
In this case you do not even need a loop:
x = (0:n - 1) * h;
y = x;
Replace:
for j = 1:n
for i = 2:n
p0(i,j)=1;
end
end
by
p0 = ones(n, n);
This is faster and nicer. Pre-allocate t also:
tau = 0.01;
t = (1:nt) * tau;
for jt = 1:nt % Vaqt bo`yicha tsikl}
% pt without loops:
pt = exp(-2 * t(jt) * x.' .* y);
% Moved out of the loops:
a = ones(1, n-1);
c = ones(1, n-1);
b = repmat(2 + 2 * h * h / tau, 1, n-1);
% k+0.s cloy
for j = 2:21 % Tenglamalar koeffitsientini hisoblash
for i = 2:n-1
% Don't do this repeatedly inside the loops - see above:
% a(i) = 1;
% c(i) = 1;
% b(i) = 2 + 2 * h * h / tau;
% You have evaluated exp(-2*x(i)*y(j)*t(jt)) already above.
% Don't do it again.
ff = h * h * (-2 * (2 * t(jt)*t(jt) * (x(i)*x(i) + y(j)*y(j)) + x(i)*y(j)) * pt(i, j));
d(i) = 2 * h * h / tau * p0(i,j) + (p0(i,j-1) - 2*p0(i,j) + p0(i,j+1)) + ff;
end
%Pragonka
aa1 = zeros(1, n-1); % Pre-allocate!
bb1 = zeros(1, n-1); % Pre-allocate!
bb1(1) = 1;
for i = 2:n-1
aa1(i) = c(i) / (b(i) - aa1(i-1) * a(i));
bb1(i) = (d(i) + bb1(i-1) * a(i)) / (b(i) - aa1(i-1) * a(i));
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
Replace:
for j=1:n
for i=1:n
p0(i,j) = p(i,j);
end
end
by
p0 = p;
Please try to implement the shown methods in your code.
Use spaces around operators and a proper indentation.
for i = 1:n
for j = 1:n
b(j) = p(i,j) - pt(i,j);
max = b(j); % ???
end
end
What is the purpose of this code? b(j) is overwritten in each iteration of i. Finally the value of max is p(n,n) - pt(n,n) and does not depend on the loop in any way. It is not worth to improve the speed of a code, when it does not compute anything useful.
  1 Comment
Shikhnazar Ismailov
Shikhnazar Ismailov on 24 Feb 2022
function []=diagonal()
n=41; ns=(n+1)/2; h=1/(n-1); nt=360;
x = zeros(1, n);
y = zeros(1, n);
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}
a = ones(1, n-1);
c = ones(1, n-1);
b = repmat(2 + 2 * h * h / tau, 1, n-1);
aa1 = zeros(1, n-1);
bb1 = zeros(1, n-1);
bb1(1) = 1;
for j=2:ns
parfor i=2:n-1
ff=h*h*(-2*(2*t(jt)*t(jt)*(x(i)*x(i)+y(j)*y(j))+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
d=2*h*h/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:ns-1
parfor i=2:n-1
ff=h*h*(-2*(2*t(jt)*t(jt)*(x(i)*x(i)+y(j)*y(j))+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
d=2*h*h/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;
for i=2:ns
parfor j=2:n-1
ff=h*h*(-2*(2*t(jt)*t(jt)*(x(i)*x(i)+y(j)*y(j))+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
d=2*h*h/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:ns-1
parfor j=2:n-1
ff=h*h*(-2*(2*t(jt)*t(jt)*(x(i)*x(i)+y(j)*y(j))+x(i)*y(j))*exp(-2*x(i)*y(j)*t(jt)));
d=2*h*h/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
px = p0(21,:);
pxt = pt(21,:);
x=0:h:1;
y=0:h:1;
figure ('Position',[600 60 700 600]);
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
The variable 'aa1' in a parfor cannot be classified.

Sign in to comment.

More Answers (0)

Categories

Find more on Loops and Conditional Statements in Help Center and File Exchange

Products


Release

R2007b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!