Need to plot multiple lines

Hi there I'm just trying to get matlab to make a simple plot with multiple lines using a for loop, and i have not had much luck anywhere else. my code is:

for a = 1:20 x = 0:0.001:2*pi; y = a*sin(x); plot(x,y) end

I want 5 lines all with different amplitude of a going from 1 to 20. However i only get one plot output with amplitude 20. What is the best way to make this happen?

Answer 1

[Paulo Silva]

hold on %put this code before your code