# Plot not generating graph

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azaandria on 3 Mar 2021
Commented: Star Strider on 3 Mar 2021
I have the below two functions and script below. I am trying to plot (a,ratio), but my graph is coming up blank?
Could someone please take a look at what Im doing wrong?
function [CL,CD] = CL_and_CD(a)
%CL_and_CD accepts alpha input,returns two outputs CL/CD
% Calculates the lift and drag co-efficients "CL" & "CD"
CL = (4.47*(10^-5*(a.^3))+(1.15*(10^-3)*(a.^2))+(6.66*(10^-2).*a)+1.02*(10^-1));
CD = (5.75*(10^-6*(a.^3))+5.09*(10^-4*(a.^2))+1.81*(10^-4.*a)+1.25*(10^-2));
end
function [ratio] = L_to_D(CL,CD)
%L_to_D accepts two inputs and returns one output
%Accepts inputs for CL & CD, and produces the Lift to Drag ratio.
ratio= CL/CD;
end
%Input
a=(-2:0.1:22);
%Call to function CL_and_CD
[CL,CD]=CL_and_CD(a);
%Call to function Ratio
[ratio]= L_to_D(CL,CD);
%Plot
plot(a,ratio);
xlabel('Angle of attack (\alpha)');
ylabel('Lift to Drag Ratio');
title('Lift to Drag Ratio by Angle of attack (\alpha)');

Star Strider on 3 Mar 2021
Do element-wise division in ‘L_to_D’:
ratio= CL./CD;
Then it works and the plotted curve appears!
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Star Strider on 3 Mar 2021
As always, my pleasure!