# Find fundamental period using stem function

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#### scdoro

##### Member level 5 Hi all,

i am new to Matlab.Could anyone help me to generate and plot the below 3 sequences using Matlab "stem" function What should i define in my script?

x1[n]=sin(0.6Пn+0.6П)
x2[n]=sin(0.68Пn)
x3[n]=3sin(1.3Пn)-4cos(0.3Пn+0.45П)

thanks alot

regards

scdoro

#### Doka

##### Junior Member level 3 from matlab 7.0 "doc stem":

Two Series of Data on One Graph
The following example creates a stem plot from a two-column matrix. In this case, the stem function creates two stemseries objects, one of each column of data. Both objects' handles are returned in the output argument h. h(1) is the handle to the stemseries object plotting the expression exp(-.07*x).*cos(x). h(2) is the handle to the stemseries object plotting the expression exp(.05*x).*cos(x). x = 0:25;
y = [exp(-.07*x).*cos(x);exp(.05*x).*cos(x)]';
h = stem(x,y);
set(h(1),'MarkerFaceColor','blue')
set(h(2),'MarkerFaceColor','red','Marker','square')

x[n]= [sin(0.6Пn+0.6П); sin(0.68Пn); 3sin(1.3Пn)-4cos(0.3Пn+0.45П)];
stem(n,x)

Good luck!

#### scdoro

##### Member level 5 hi Dova,

The following MATLAB function can be used to compute samples of the
DTFT of a
finite length signal.

Qn1) Can someone explain how this function works line by line?

**********************************************
Function [H,W] = dtft(x, n)
% Calculates DTFT of x at n equally spaced frequencies
% Usage:
% x: finite-length input vector (of length L)
% n: number of frequencies for evaluation over
% [-pi,pi]. n>=L.
% H: DTFT values
% W: vector of frequencies where DTFT is computed.
n=fix ;
L=length(x); h=h )
if (n < L)
error(‘DTFT: #data samples cannot exceed # freq samples.’)
end
W = (2*pi/n) * [0 n-1)]’;
mid = ceil(n/2) + 1;
W(mid:n) = W(mid:n) – 2*pi;
W = fftshift(W);
H = fftshift( fft(h,n) );

**********************************************************

Qn2) plot the magnitude and phase responses of the signal xn, given
by

a = 0.88 * exp( j*2*pi/5 );
nn = 0:40;
xn = a.^nn;
for n = 128.

thanks

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