This is the last one, which is similar to 03_quechb.
Set the tau value in echo.conf:

set tau 200	   ;# here you want to assign your tau value

You will input the velocity distribution 300.vel generated from 
your previous simulation:

velocities          ../04_consta/300.vel

Run your simulation and store your data file:

gettemp youroutputfile > temp3.dat

Copy temp1.dat and temp2.dat to this directory:

cp ../01_equil_NVE/temp1.dat .
cp ../04_consta/temp2.dat .

Combine all of them:

cat temp[1-3].dat > temp.dat

Start Matlab, type in 

matlab -nosplash &

Load in your data:

load temp.dat

Plot it:

plot(temp(:,1),temp(:,2))

Input your tau,

tau= the number you are assigned

Plot the simulated echo and the harmonic approximation:

cmp_echo(tau,temp)

Get the depth of the echo:
300 - min(temp(510+tau:end,2))

You are done. Congratulations!
