How to randomly add variance in a graph plot

I'm graphing y=x, but I want to add a second plot of black stars where y is randomly + or - 0.25 I know the code to plot is

plot (x,y2, 'k*')

but how do I randomly add noise to create y2?

Answer 1

[Star Strider]

Experiment with the randn and rand functions to get the result you want.

[Krish Desai]

But don't I need to do use the rand function each time then? So for x=1 I would have to use rand(2) and have 1 correspond with .25 and 2 with -.25. But then I would have to do this 10 more times. I want to make it more efficient. Would I be able to create a new vector and add this to y2?

[Walter Roberson]

http://www.mathworks.com/help/matlab/ref/rand.html#input_argument_sz1szn