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I want to populate an empty array, and then access individual elements from within a function.

a = [];

for i=1:10
  a(i)=i;
end

function display_a(k)
  a = a(k);
  disp(a);
end

display_a(5)

Here I receive an error:

'a' undefined near line 8, column 7

Which means that a=a(k) within the function is not recognized as my array a. Any idea on how to pull this off?

I tried declaring a as a global variable. Apart from my understanding that declaring global variables is not a good practice, my function returns the whole array instead of just one, specified element.

Thank you in advance.

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3
  • 1
    You need to pass the array into the function. Each function has its own scope, and does not see variables declared in other scores. Declare the function as function display_a(a,k). Commented Sep 30, 2022 at 19:52
  • 1
    Besides, avoid assignments like a = a(k) because after that the array a(:) becomes a scalar a (unless this is really what you want). Use an intermediate variable b=a(k); disp(b) or even directly disp(a(k)) Commented Sep 30, 2022 at 20:14
  • Thank you @CrisLuengo, that worked like a charm. In hindsight it's so obvious, I was aware of what the scope of the function is and tried to "solve" it by declaring a global variable, but I wasn't really able to connect all the dots myself - thanks! PierU, definitely, sorry about introducing the ambiguity into this example, I'd never do that in the actual working code. Commented Sep 30, 2022 at 20:22
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