# Plot two looping variables

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Tomas White on 2 May 2022
Commented: Voss on 3 May 2022
Hello! I have this code which generates multiple values of the variable "CL" by iterating the variable "aoa", my problem is that when I try to plot both variables I generate a graph per "aoa" iteration and not all iterations in a single graph. I tried various methods and code combinations but nothing seems to do the job. Any help is much aprreciated!
%LLT
fprintf('Lifting line theory - 7.1 \n')
%Inputs
fprintf('------------------------------------------------------------- \n')
zeroliftd=-1.2;
aoainitiald=4;
aoafinald=10;
AR=9;
fprintf('------------------------------------------------------------- \n')
aoainitial=((aoainitiald*pi)/180);
aoafinal=((aoafinald*pi)/180);
zerolift=((zeroliftd*pi)/180);
%Station phi values
station=[1,2,3,4]';
s1phi=22.5;
s2phi=45;
s3phi=67.5;
s4phi=90;
phin=[s1phi,s2phi,s3phi,s4phi];
phi=phin.';
%Calculus - table 7.1
cosphi=cosd(phi);
sinphi1=sind(phi);
sinphi3=sind(3*phi);
sinphi5=sind(5*phi);
sinphi7=sind(7*phi);
miu=0.24933*(1-0.6*cosd(phi));
aoa=aoainitial;
while ((aoa) <= (aoafinal))
%table 7.1 display
fprintf('------------------------------------------------------------- \n')
fprintf('------------------------------------------------------------- \n')
fprintf('Math process corresponding to angle of attack (degrees) =')
dispaoa=aoa*(180/pi);
disp(dispaoa)
matrix1=[station,phi,cosphi,sinphi1,sinphi3,sinphi5,sinphi7,miu];
fprintf('Table 7.1: \n')
disp(matrix1);
fprintf('------------------------------------------------------------- \n')
%equation 7.31
%equation second member
L1=((matrix1(1,8))*(aoa-zerolift)*(matrix1(1,4)));
L2=((matrix1(2,8))*(aoa-zerolift)*(matrix1(2,4)));
L3=((matrix1(3,8))*(aoa-zerolift)*(matrix1(3,4)));
L4=((matrix1(4,8))*(aoa-zerolift)*(matrix1(4,4)));
Ltotaln=[L1,L2,L3,L4];
Ltotal=Ltotaln';
fprintf('Second member matrix for equation system 7.31: \n')
disp(Ltotal);
fprintf('------------------------------------------------------------- \n')
%matrix: A1
ma11=(matrix1(1,4))*((matrix1(1,8))+(matrix1(1,4)));
ma13=(matrix1(2,4))*((matrix1(2,8))+(matrix1(2,4)));
ma15=(matrix1(3,4))*((matrix1(3,8))+(matrix1(3,4)));
ma17=(matrix1(4,4))*((matrix1(4,8))+(matrix1(4,4)));
ma1n=[ma11,ma13,ma15,ma17];
ma1=ma1n';
%matrix: A3
ma31=(matrix1(1,5))*(3*(matrix1(1,8))+(matrix1(1,4)));
ma33=(matrix1(2,5))*(3*(matrix1(2,8))+(matrix1(2,4)));
ma35=(matrix1(3,5))*(3*(matrix1(3,8))+(matrix1(3,4)));
ma37=(matrix1(4,5))*(3*(matrix1(4,8))+(matrix1(4,4)));
ma3n=[ma31,ma33,ma35,ma37];
ma3=ma3n';
%matrix: A5
ma51=(matrix1(1,6))*(5*(matrix1(1,8))+(matrix1(1,4)));
ma53=(matrix1(2,6))*(5*(matrix1(2,8))+(matrix1(2,4)));
ma55=(matrix1(3,6))*(5*(matrix1(3,8))+(matrix1(3,4)));
ma57=(matrix1(4,6))*(5*(matrix1(4,8))+(matrix1(4,4)));
ma5n=[ma51,ma53,ma55,ma57];
ma5=ma5n';
%matrix: A7
ma71=(matrix1(1,7))*(7*(matrix1(1,8))+(matrix1(1,4)));
ma73=(matrix1(2,7))*(7*(matrix1(2,8))+(matrix1(2,4)));
ma75=(matrix1(3,7))*(7*(matrix1(3,8))+(matrix1(3,4)));
ma77=(matrix1(4,7))*(7*(matrix1(4,8))+(matrix1(4,4)));
ma7n=[ma71,ma73,ma75,ma77];
ma7=ma7n';
%matrix system
%equation first member
equationmatrix1=[ma1,ma3,ma5,ma7];
fprintf('First member matrix for equation system 7.31: \n')
disp(equationmatrix1);
fprintf('------------------------------------------------------------- \n')
%equation system solver
matrixA=linsolve(equationmatrix1,Ltotal);
%An matrix
fprintf('Equation system 7.31 solution: \n')
fprintf('A1 = ')
disp(matrixA(1,1));
fprintf('A3 = ')
disp(matrixA(2,1));
fprintf('A5 = ')
disp(matrixA(3,1));
fprintf('A7 = ')
disp(matrixA(4,1));
fprintf('------------------------------------------------------------- \n')
%Lift coefficient for inputed angle of attack:
fprintf('Corresponding CL for inputed angle of attack:\n')
CLin=(matrixA(1,1))*3.14159*AR;
fprintf('CL:');
disp(CLin);
fprintf('------------------------------------------------------------- \n')
%Theoretical value of induced drag coefficient for inputed angle of attack:
fprintf('Corresponding induced theorical CD for inputed angle of attack:\n')
CDin=(((CLin)^2)/(3.14159*AR))*(1+((3*(matrixA(2,1))^2)/((matrixA(1,1))^2))+((5*(matrixA(3,1))^2)/((matrixA(1,1))^2))+((7*(matrixA(4,1))^2)/((matrixA(1,1))^2)));
fprintf('Cd:');
disp(CDin);
aoa=aoa+pi/180;
end
plot(aoa,CLin);

Voss on 2 May 2022
In order to see how aoa and CLin change in each iteration of the while loop, you can either: (1) plot them each time through the loop, or (2) collect all their values in arrays and plot the arrays after the loop.
Method 1 would have this kind of structure:
aoa=aoainitial;
while aoa < aoafinal
% ...
% calculate CLin
% ...
plot(aoa,CLin,'o'); % 'o' is a data marker, which is necessary to see a line with only one point
hold on % use hold on to keep each plotted line (in this case each plotted point)
aoa=aoa+pi/180;
end
Method 2 would have this kind of structure:
aoa_array = [];
CLin_array = [];
aoa=aoainitial;
while aoa < aoafinal
% ...
% calculate CLin
% ...
aoa_array(end+1) = aoa; % add the new values to the end of the arrays
CLin_array(end+1) = CLin;
aoa=aoa+pi/180;
end
plot(aoa_array,CLin_array); % plot the arrays
##### 2 CommentsShowHide 1 older comment
Voss on 3 May 2022
You're welcome!

R2020a

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