how to do zero padding for a vector?

please help. i have just started learning matlab .

Answer 1

[Azzi Abdelmalek]

A=[1 2 3]
B=[A zeros(1,3)]

[g.p]

THANKS ITS SIMPLE. IT WORKS.

[ARPITKUMAR PATEL]

thanks, simple

Answer 2

[John BG]

Grupeet

the padding you may have in mind is the actual interpolation of zeros blocks after each symbol.

    A=[1 2 3]
    B=[A zeros(1,3)]

length of the padding

    N=4

then

     B=zeros(1,N*length(A))
     =
         0     0     0     0     0     0     0     0     0     0     0     0
    B([1:N:end])
     =
         0     0     0
    B([1:N:end])=A
     =
         1     0     0     0     2     0     0     0     3     0     0     0

In the example, appeneded DTFT code

http://uk.mathworks.com/help/signal/ug/amplitude-estimation-and-zero-padding.html

it is clearly mentioned, the fft(x,2000) one-off zero padding in frequency domain helps reach the correct fft amplitude plot

Without FFT frequency zero padding

   Fs = 1e3;
    t = 0:0.001:1-0.001;
    x = cos(2*pi*100*t)+sin(2*pi*202.5*t);
    xdft = fft(x);
    xdft = xdft(1:length(x)/2+1);
    xdft = xdft/length(x);
    xdft(2:end-1) = 2*xdft(2:end-1);
    freq = 0:Fs/length(x):Fs/2;
    figure(1);plot(freq,abs(xdft))
    hold on;
    figure(1);plot(freq,ones(length(x)/2+1,1),'LineWidth',2)
    xlabel('Hz');ylabel('Amplitude');hold off;

with FFT frequency zero padding

    xdft = fft(x,2000);
    xdft = xdft(1:length(xdft)/2+1);
    xdft = xdft/length(x);
    xdft(2:end-1) = 2*xdft(2:end-1);
    freq = 0:Fs/(2*length(x)):Fs/2;
    figure(2);plot(freq,abs(xdft));
    hold on;
    figure(2);plot(freq,ones(2*length(x)/2+1,1),'LineWidth',2)
    xlabel('Hz'); ylabel('Amplitude');
    hold off;

Gurpreet would you please be so kind to mark my answer as Accepted Answer?

To any other reader, please if you find this answer of any help solving your question,

please click on the thumbs-up vote link,

thanks in advance

John BG

<mailto:[e-mail] [e-mail]>

[g.p]

GREAT ONE COMPLETELY HELPFULL. THANKS A LOT. CAN U TELL ME HOW TO PADD IN 000123 RATHER THAN 123000. PRE PADDING ??

[Superunknown]

@John BGllorón