Add a legend in a plot with multiples lines

Hi, I am having a small probllem in adding a legend, I just can't get all the names for different frequencies:

clear all;
close all;

load psi_20.mat
load time_20.mat

psi_20 = psi;
time_20 = time;

plot(time_20,psi_20)
legend('20Hz')
hold on

load psi_40.mat
load time_40.mat

psi_40 = psi;
time_40 = time;

plot(time_40,psi_40)
legend('40Hz')
hold on

load psi_60.mat
load time_60.mat

psi_60 = psi;
time_60 = time;

plot(time_60,psi_60)
legend('60Hz')
hold on

load psi_80.mat
load time_80.mat

psi_80 = psi;
time_80 = time;

plot(time_80,psi_80)
legend('80Hz')
hold on

load psi_100.mat
load time_100.mat

psi_100 = psi;
time_100 = time;

plot(time_100,psi_100)
legend('100Hz')
hold on

I have matlab 2014b

Answer 1

[Mathieu NOE]

hi

simplest code below - more sophisticated is always possible...

% simple code 
load psi_20.mat
load time_20.mat
psi_20 = psi;
time_20 = time;

load psi_40.mat
load time_40.mat
psi_40 = psi;
time_40 = time;

load psi_60.mat
load time_60.mat
psi_60 = psi;
time_60 = time;

load psi_80.mat
load time_80.mat
psi_80 = psi;
time_80 = time;

load psi_100.mat
load time_100.mat
psi_100 = psi;
time_100 = time;

plot(time_20,psi_20,time_40,psi_40,time_60,psi_60,time_80,psi_80,time_100,psi_100);
legend('20Hz','40Hz','60Hz','80Hz','100Hz')

Answer 2

[Durganshu]

Don't use legend multiple times.

You can use this command after plotting all the plots.

legend('20Hz', '40Hz', '60Hz', '80Hz', '100Hz')

Hope this helps!