How to make a grid periodic

I have the code below to plot grid lines for the y values

clear all; close all; clc;
y =[-0.906   -0.120    0.664    1.450    2.235    3.021    3.806    4.591    5.377];

for i=1:length(y)
    plot(0:1:10, y(i)+(0:1:10).*0,'m');
    hold on
end

I want to make it repeat at least twice above and below with a period 2*pi . Any help on how to achieve this will be greatly appreciated.

Answer 1

[DGM]

Do you actually need plot lines, or are you trying to make the plot gridlines have a particular spacing?

If the latter, consider the example:

y=linspace(0,6*pi,100);
x=sin(y);

plot(x,y); grid on
yl=get(gca,'ylim');
set(gca,'ytick',(yl(1):pi/4:yl(2))-0.906)

Of course, that -0.906 offset obfuscates that the spacing is a nice pi/4

On the other hand, if you really just want a bunch of lines plotted, you can do that too.

clf
% pick how far you want the lines to extend in x and y
x=[1 10];
yl=[-2*pi 2*pi]; 

% calculate the array
y=repmat((yl(1):pi/4:yl(2))'-0.906,[1 2]);
plot(x,y,'b')