How to convolve and plot fft of cosine function

X1[n]=3*cos((2*pi*3*n)/25); X2[n]=6*cos((2*pi*9*n)/25); X3[n]=9*cos((2*pi*12*n)/25); k=1,2,3 X[n] = summation from k=1 to 3 of (Xk[n])

I need to convolve each Xk[n] with X[n] and find the length of each sequence

Answer 1

[Ankitha Kollegal Arjun]

To perform convolution of 2 sequences, the conv() function can be used. To find the length of a sequence, the length() function can be used. Here is an example:

n = 0:10;
x1 = 3*cos((2*pi*3*n)/25);
x2 = 6*cos((2*pi*9*n)/25);
x3 = 9*cos((2*pi*12*n)/25);
x = x1+x2+x3;
conv_x1 = conv(x1,x);
length_conv_x1 = length(conv_x1);
conv_x2 = conv(x2,x);
length_conv_x2 = length(conv_x2);
conv_x3 = conv(x3,x);
length_conv_x3 = length(conv_x3);

FFT of a sequence can be obtained using fft() function.