Companding of signal using MULAW in MATLAB

clear all
close all
clc
M=input('enter the signal') %enter the signal with time like sin(2*pi*[0:0.01:1]
Mmax=max(M)
Mn=M/Mmax
u=input('enter the u value') %default value is 255
Vn=log(1+u*Mn)/(log(1+u))
 figure(1)
 plot(Mn)
 figure(2)
 plot(Vn)
 figure(3)
plot(Mn,Vn)