Plot area is empty

When I plot a function for displacement versus angular position it yeilds a plot. When I plot a function for velocity versus angualar position, it yields a blank plot. This may have to do with my raising the sin/cos terms to powers higher than 1 but I am not sure.

Take a look:

clear;clc;

w=1;

a=0:1:48.1;

y=(95./cosd(a))-95;

yv=(95*w*sind(a))/((cosd(a)).^2);

ya=(95*w^2*(2-((cosd(a)).^2)))/((cosd(a)).^3);

plot(a,y,'r',a,yv,'b',a,ya,'g')

title('magnitude vs angular position')

xlabel('angular postition (θ)')

ylabel('y,c,a')

Answer 1

[Star Strider]

Use element-wise (array) division (./) instead of matrix division (/) and it works. (Matrix division will produce one value, however that will not plot because the plot function only plots lines between points, not the points themselves, unless a marker is also specified.)

This is the most common problem I see on MATLAB Answers.

w=1;
a=0:1:48.1;
y=(95./cosd(a))-95;
yv=(95*w*sind(a))./((cosd(a)).^2);
ya=(95*w^2*(2-((cosd(a)).^2)))./((cosd(a)).^3);

figure
plot(a,y,'r',a,yv,'b',a,ya,'g')
title('magnitude vs angular position')
xlabel('angular postition (θ)')
ylabel('y,c,a')

Consider including a legend to identify the curves.

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[Simba Nduna]

Thanks a lot @Star Strider.

[Star Strider]

As always, my pleasure!

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