# How can I solve in the error?

5 views (last 30 days)
Myo Gyi on 20 Dec 2022
Commented: Myo Gyi on 20 Dec 2022
clear all, clc; % clear all memory and variables
x = linspace(-1,1); % create linear spacing in x-direction
y = linspace(-1,1); % create linear spacing in y-direction
%initialise velocity
U = 1.; %freestream velocity
%looping in i and j-directions
for i = 1:length(x)
for j = 1:length(y)
%create x & y space
xx(i,j) = x(i);
yy(i,j) = y(j);
%calculate radius from x & y
% calculate angle from x and y
if x(i) > 0
theta(i,j) = atan(y(j)/x(i));
elseif x(i) <0 && y(j) >= 0
theta(i,j) =atan(y(j)/x(i))+pi;
elseif x(i) < 0 && y(j) < 0
theta(i,j) = atan(y(j)/x(i))-pi;
elseif x(i) == 0 && y(j) < 0
theta(i,j) = pi/2;
else
theta(i,j) = pi/2;
end
% calculate stream function using polar coordinate system
% calculate velocity potential using polar coordinate system
end
end
%plotting
contourf(xx,yy,psi,-1:0.2:1,k,LineWidth,1.5), hold on % plot stream function for range -1:0.1:1
contour(xx,yy,phi,-1:0.2:1,r,LineWidth,1.5) % plot velocity potential for range -1:0.2:1
axis image, hold off
legend(streamlines,potential)
title(Uniform stream in x-direction)
xlabel(x-coordinate), ylabel(y-coordinate)
axis square;
% end of Octave program
Karim on 20 Dec 2022
Which error?
After correcting the apostrophes and the minus sign the code appears to run without issues?
Myo Gyi on 20 Dec 2022
Thank you sir... Can You repair for my code sir.

Stephan on 20 Dec 2022
%clear all, clc; % clear all memory and variables
x = linspace(-1,1); % create linear spacing in x-direction
y = linspace(-1,1); % create linear spacing in y-direction
%initialise velocity
U = 1.; %freestream velocity
%looping in i and j-directions
for i = 1:length(x)
for j = 1:length(y)
%create x & y space
xx(i,j) = x(i);
yy(i,j) = y(j);
%calculate radius from x & y
% calculate angle from x and y
if x(i) > 0
theta(i,j) = atan(y(j)/x(i));
elseif x(i) <0 && y(j) >= 0
theta(i,j) =atan(y(j)/x(i))+pi;
elseif x(i) < 0 && y(j) < 0
theta(i,j) = atan(y(j)/x(i))-pi;
elseif x(i) == 0 && y(j) < 0
theta(i,j) = pi/2;
else
theta(i,j) = -pi/2;
end
% calculate stream function using polar coordinate system
% calculate velocity potential using polar coordinate system
end
end
%plotting
contourf(xx,yy,psi,-1:0.2:1,'k','LineWidth',1.5), hold on % plot stream function for range -1:0.1:1
contour(xx,yy,phi,-1:0.2:1,'r','LineWidth',1.5) % plot velocity potential for range -1:0.2:1
axis image, hold off
legend('streamlines','potential')
title('Uniform stream in x-direction')
xlabel('x-coordinate'), ylabel('y-coordinate')
axis square;
Myo Gyi on 20 Dec 2022
Thanks Sir.... Can I get more pitcure like this side
https://people.utm.my/ridhwan/teaching/skme-3333-aerodynamics/potential-flow/