plot 3 horizontal lines

I have a simple x,y plot of values. I want to plot 3 additional horizontal lines, one being the mean, one being 2 standard deviations above, and one being 2 standard deviations below. I figured out how to plot the mean but I can't figure out how to plot the standard deviations on the same plot.

Answer 1

[Vishnu]

Hey @Chris!

I see that you want to create a plot with horizontal lines representing values above and below the mean by 2 standard deviations. Here is an example oh how we can achieve this:

A = [4 5 1];
t = [1 2 3];
plot(t,A)

hold on

avg = mean(A);
deviation = std(A);

yline(avg,"g")
yline(avg+2*deviation,"r")
yline(avg-2*deviation,"b")

hold off

Note the hold on and hold off is used to keep plotting onto the same plot. for further reading you can check out the following documentations:

Standard Deviation

Plotting Horizontal Lines

[John D'Errico]

I accepted this accurate answer, since the question was an old one and might not get seens by the OP.