CODEWITHSUNDEEP
matlabsignal-processing
222
222

Reputation: 95

Incrementing a variable inside a function on MATLAB

My goal is being able to graph the following:

x(n)= delta(n)+delta(n-1)+delta(n-2)+….+delta(n-10)+delta(n-11)

I have written this code:

n = -15:15
e(m) = dirc(n(m));
k = 1
for m = 1 : length(n)
    while k < 12
        e_1(m) = dirc(n(m)-k);
        k = k + 1
    end
    e(m) = e(m) + e_1(m)
end

subplot(4,4,5);
stem(n,e,'m','markersize',3,'linewidth',1)
xlabel('n')
ylabel('\delta[n]') 
title ('(e)')

and I wrote the function dirc as follows: 

function output = dirc(input)
output = 0;
if input == 0
    output = 1;
end
end

The error is

Index exceeds matrix dimensions

As you can see, this is a terminating function, I'd like to be able to graph something like this eventually:

x(n)= delta(n)+delta(n-1)+delta(n-2)+….

Upvotes: 0

Views: 390

Answers (1)

Andras Deak -- Слава Україні
Andras Deak -- Слава Україні

Reputation: 35109

You're not showing us what m is in the second line, that's a probable source of your problems. Also, you'll have to pre-allocate the vector e if you want to increment its values in a loop, this can also give you out-of-bounds errors.

As for the rest of your code, you can replace dirc(input) with simply input==0, the resulting logical values will be compatible with numerical 0 and 1 (in case the input is scalar, which seems to be the case for you).

As a matter of fact, what you're trying to achieve is the function

kmax = 11;
xfun = @(n) ismember(n,0:kmax);  %// anonymous function
x(n) = xfun(n);                  %// evaluate at any specific value n

or if you want to compute x(n) for multiple values of n at once:

kmax = 11;
xfun = @(n) sum(bsxfun(@eq,n(:),0:kmax),2);%// anonymous function
xvec = xfun(-15:15);                       %// evaluate at every n simultaneously

Upvotes: 2

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