Matlab - Teorema de Parseval

Fs=128;

t=0:1/Fs:8*60;

f1=2; f2=3;

f3=5; f4=6;

f5=9; f6=12; f7=14;

f8=17; f9=23; f10=28;

rng('default')

x1=1*cos(2*pi*f1*t)+1*sin(2*pi*f2*t)+1*sin(2*pi*f3*t)+1*sin(2*pi*f4*t)+1*rand(1,61441)...

    +1*cos(2*pi*f5*t)+1*sin(2*pi*f6*t)+1*sin(2*pi*f7*t)+1*sin(2*pi*f8*t)+1*sin(2*pi*f9*t)+1*sin(2*pi*f10*t);

plot(x1);

a=rand(11);

A=fftn(a); A=A/sqrt(numel(A));

anew=ifftn(A); anew=anew*sqrt(numel(anew));

E1=norm(a(:))^2,

E2=norm(A(:))^2,

E3= norm(anew(:))^2

E4=sum(abs(a(:)).^2)