# How to find highest and lowest numbers in vector without using build in functions?

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Roko Serdar on 10 Apr 2021 at 12:45
Answered: Walter Roberson on 10 Apr 2021 at 14:37
I have a task to find highest and lowest numbers in vectros using while and if
Any help would mean a lot to me since I'm only a begginer and have no Idea how to do this

Walter Roberson on 10 Apr 2021 at 14:37
Both while and if are keywords rather than functions, so saying that those are permitted to be used does not alter what can be done without functions.
In short: in order to compare numbers to each other you have to do a computation (checking to see if they are equal, at the very least), and all computation involving two numbers in MATLAB involves using built-in functions, but you are not permitted to use built-in functions.
Example:
A = 3; %does not involve any functions
if A == 1 %involves the function eq()
elseif A < 3 %involves the function le()
end
So you cannot compare x(1) to x(2) without using a comparison and that involves using a built-in function.
There are computer languages where comparisons and very simple indexing are both built-in operators, and with those languages it is technically possible to sort a fixed-length vector without using any built-in functions... but it might be very tedious. And those languages are not MATLAB.