Why is plot(x,y=0) not giving a line at y=0?

I am trying to plot a function with a line through y=0 too.

I wrote this code:

x=0:0.01:10*pi;
plot(x,2*sin(x).*exp(-x/4));
hold on
y=0;
plot(x,y)

This is only giving me a curve and no line through y=0.

I am getting the y=0 line with this code:

x=0:0.01:10*pi;
plot(x,2*sin(x).*exp(-x/4));
hold on
y=zeros(length(x));
plot(x,y)

So what is happening with the pervios code? Doesnt y=0; make any sense here?

Answer 1

[madhan ravi]

Stephen’s answer is the way I would do it but the explanation for the not satisfactory result of your code:

y=0;

You create a scalar and you try to plot it with x which is vector, it doesn't work like that in MATLAB you should have done

plot(x,zeros(size(x))) % this creates zeros as same size as x.

Answer 2

[Stephan]

Hi,

no need for this - since you are using R2018b you can take advantage of the yline function:

x=0:0.01:10*pi;
plot(x,2*sin(x).*exp(-x/4))
yline(0,'r--');

Best rregards

Stephan