How to create impulse from timestamps?

Hi i have an array x=[ 1 11 21 31 41 51 61 71 81 91] i would like to create an impulse function of a=[0 1 0 0 0 0 0 0 0 0 0 1 0 0 ....] my script is as follows

    function= zeros(1,max(a)
    for n=1 : max(a)
    if n==a
    x(n)=1
    end
    end

but what i get is just function = [ 0 0 0 0....] seems like this line " if n==a x(n)=1 " isnt working

Answer 1

[dpb]

function= zeros(1,max(a)
  ...

The above is surely not your actual attempt is it?

If so, and you named it owing to Matlab convention you just aliased the builtin zeros which undoubtedly will lead to mass confusion and errors going forward.

Try pulse or somesuch name instead...

function p = pulse(idx)
  % return array w/ 1 at positions in idx beginning w/ a 0

    p=zeros(1,max(x)+1);  % zero vector of length max pos'n + initial 0
    p(idx)=1;

In Matlab, don't need any loops or tests, just use the values as the index vector.

ADDENDUM:

The above assumes a given vector location--if you want instead a fixed difference, then you'll have to define how many pulses you want to determine the length but you can then dispense with the input vector in favor of an interval and number--

function p = pulseb(dx,N)
  % return array w/ 1 at N positions in idx beginning w/ a 0 
  % with spacing of dx

    idx=1:dx:N*dx;          % the index vector from 1 for N pulses
    p=zeros(1,max(idx)+1);  % zero vector of length max pos'n + initial 0
    p(idx)=1;

ADDENDUM 2:

Or, of course, you could have more general logic and use the number of parameters passed to the function imply the form--two could be the SPACING, COUNT whereas >3 could be interpreted as the LOCATIONS.

Answer 2

[Mischa Kim]

You could also do

 x = [1 11 21 31 41 51 61 71 81 91];
 n = 11;
 a = x==n;

[Fam]

the x was just a sample so the period just happened to be 11. i was hoping to do it in all cases

[Mischa Kim]

So what would be your most general case, and the expected result?