# how to change x and y values to a range of values

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Avenger2020 on 23 Nov 2020
Commented: Avenger2020 on 23 Nov 2020
How can i change the variables X and Y values to a range of values in the code below? Its already in a loop and i used "hold on" to keep the plots previosly so the results are combined in one graph. Thanks in advance. In the code below i used one value for X and one value for Y, but i'd like to use the Y value range that i commented in the code.
clear all
clc
Vinf=100; % Input Vinf
a=deg2rad(15); % Input Alpha in degrees
N=100; % Number of Free Vortexes
c=1; % Length of chord c
X=-2*c;
% Y=linspace(-.7*c,0.1*c,20);
Y=-.7*c;
DeltaT=4e-8;
k=nonzeros(0:c/N:1);
for i=1:length(k)
s(i)=k(i); % si
s1=k(i)-(c/N); % si-1
% s2 is the center of free vortex i
s2=(s(i)+s1)*0.5;
ai=(s2*cos(a));
bi=((-s2)*sin(a));
Thetai=acos(1-2*s(i)); % θi
Thetai_1=acos(1-2*s1); % θi-1
G1(i)=(a*Vinf)*(Thetai-Thetai_1);
G2(i)=(2*a*Vinf)*[(sqrt(s(i)-s(i).^2))-(sqrt(s1-s1.^2))];
% Stength Gi of free vortex "i"
G(i)=G1(i)+G2(i);
u(i)=(G(i)/(2*pi))*((Y-bi)/((X-ai)^2+(Y-bi)^2));
v(i)=((-G(i))/(2*pi))*((X-ai)/((X-ai)^2+(Y-bi)^2));
end
UDT=u*DeltaT;
VDT=v*DeltaT;
DD=X+UDT;
D2=Y+VDT;
plot(DD, D2,'-or')
hold on

VBBV on 23 Nov 2020
X=linspace(-2*c,1*c,20); % define X vector similar to Y but of same number of divisions i.e. 20
Y=linspace(-.7*c,0.1*c,20);
%Y=-.7*c;
DeltaT=4e-8;
k=nonzeros(0:c/N:1);
for jj = 1:length(X) % use another for loop for vectors X, Y
for i=1:length(k)
s(i)=k(i); % si
s1=k(i)-(c/N); % si-1
% s2 is the center of free vortex i
s2=(s(i)+s1)*0.5;
ai=(s2*cos(a));
bi=((-s2)*sin(a));
Thetai=acos(1-2*s(i)); % θi
Thetai_1=acos(1-2*s1); % θi-1
G1(i)=(a*Vinf)*(Thetai-Thetai_1);
G2(i)=(2*a*Vinf)*[(sqrt(s(i)-s(i).^2))-(sqrt(s1-s1.^2))];
% Stength Gi of free vortex "i"
G(i)=G1(i)+G2(i);
u(i,jj)=(G(i)/(2*pi))*((Y(jj)-bi)/((X(jj)-ai)^2+(Y(jj)-bi)^2)); % use the loop index where X & Y occurs
v(i,jj)=((-G(i))/(2*pi))*((X(jj)-ai)/((X(jj)-ai)^2+(Y(jj)-bi)^2));
end
end
Define the X vector similar to Y vector as you did, Add another for loop and use its index where X and Y vectors occurs

Avenger2020 on 23 Nov 2020
i can't change the c values, the other formulas will change if i change c. Can you help with changing it into a function ? I'm not that great with functions.
Rik on 23 Nov 2020
Put all the code to do 1 element that should be plotted in a separate script, put function at the top of that file and you have written your first function. What is 1 element in your context?
Avenger2020 on 23 Nov 2020
1 element would be at x=-2 and the 20 different values of y