problem with a matlab code for discrete-time convolution

Here is my code.

n= -25:25

x= cos(2*pi*n/.3).*(n>=0)

h= (cos(pi*n/.3)+(sin(pi*n/3)/sqrt(3))).*(n>=0)

y= conv(h,x)

plot(n,x)

hold on

plot(n,h)

hold on

plot(n,y)

title ('Plot of input X[n], impulse response h[n] and the convolution of the two Y[n]')

xlabel ('Variable n')

ylabel ('amplitude of signal')

hold on

I have got to plot the input x, impulse response h and the convolution of the two using the conv command but i am getting the error

"??? Error using ==> plot
Vectors must be the same lengths.

Error in ==> lab6p3 at 9
plot(n,y)"

I am using the R2011a student version of matlab

thank you in advance

Answer 1

[Wayne King]

 n= -25:25;
 x= cos(2*pi*n/.3).*(n>=0);
 h= (cos(pi*n/.3)+(sin(pi*n/3)/sqrt(3))).*(n>=0);
 y= conv(h,x);
 n1 = -25:length(y)-1-25;
 stem(n1,y,'markerfacecolor',[0 0 1]);

Answer 2

[Wayne King]

You have to realize the result of linearly convolving two input signals, h and x, is length(h)+length(x)-1

so you need a new n vector that matches your output y in length.

Your y vector has the expected length of length(h)+length(x)-1 = 101

[Benjamin]

How would I do that?

sorry still getting used to matlab

Answer 3

[Gui Chen]

You should take care of the length after the convolution. You could take a look at this video. https://youtu.be/JlUM0XHTSSQ