Chirp plot is not drawing

My chirp function is not being drawn for some reason, only stem samples are visible. If comment out stem command the plot is being drawn but to time 2e-3.

function fun6

tmax=4e-3;

T=2e-3;

fs=6e3;

xmax=2;

f1=0.5e3;

f2=1.5e3;

t=linspace(0,tmax,2001);

tt=mod(t,T);

x=xmax*chirp(tt,f1,T,f2);

n=fix(tmax*fs);

td=(0:n-1)/fs;

tdd=mod(td,T);

xd=xmax*chirp(tdd,f1,T,f2);

close all;

plot(tt,x,'b');

stem(td,xd,'r*');

grid on;zoom on;hold on;

Answer 1

[Cris LaPierre]

You need to place hold on before you add a second plot to your axes. Your code currently replaces the plot with the stem plot.

Your plot only goes to 2e-3 because that is what you define tt using mod. Perhaps you meant to use t when plotting?

tmax=4e-3;
T=2e-3;
fs=6e3;
xmax=2;
f1=0.5e3;
f2=1.5e3;

t=linspace(0,tmax,2001);

tt=mod(t,T);
x=xmax*chirp(tt,f1,T,f2);
n=fix(tmax*fs);
td=(0:n-1)/fs;
tdd=mod(td,T);
xd=xmax*chirp(tdd,f1,T,f2);

plot(t,x,'b'); % changed tt to t
hold on
stem(td,xd,'r*');
hold off