MATLAB: Plotting multiple graphs and adding a straight line

MATLABplotting

I am trying to plot multiple graphs, and I want to add a straight line of y = 2.3 into the graph but it only shows my first two plots which are x1,OA and x2,OF.
here is my code
x1 = [0:1:101];
OA = 0.00022494*x1.^2;
x2 = [0:1:74.4];
OF = -0.00018056*x2.^2;
x3 = [101:1:265];
AC = 2.3;
plot(x1,OA,'r',x2,OF,'r',x3,AC,'r')

Best Answer

There are at least 2 ways to do that:
x1 = [0:1:101];
OA = 0.00022494*x1.^2;
x2 = [0:1:74.4];
OF = -0.00018056*x2.^2;
x3 = [101:1:265];
AC = 2.3;
figure
plot(x1,OA,'r',x2,OF,'r',x3,AC,'r')
yline(2.3) % First Option
figure
plot(x1,OA,'r',x2,OF,'r',x3,AC,'r')
hold on
plot(xlim, [1 1]*2.3, '-b') % Second Option
hold off
.