The n given to tempcorrect is a vector (of length 10000). When you use a vector (or matrix, or any array) in an if statement, the if condition is considered true only if it is true for all elements of that vector (or matrix or array).
if [1 2 3] > 2
disp('true');
else
disp('false')
end
if [1 2 3] > 0
disp('true');
else
disp('false')
end
It turns out the n given to tempcorrect is such that all the if and elseif conditions checked in the function are false for at least one element of n, so the else block executes and you get per = 100 as output.
To have tempcorrect operate on one element of n at a time, you can give it one element of n at a time and collect the results in a vector:
a = zeros(size(iot_temperture))
for ii = 1:numel(iot_temperture)
a(ii) = tempcorrect(iot_temperture(ii));
end
Or you can adapt tempcorrect to work for array inputs, either by putting the loop in the function itself, or by using logical indexing:
function per = tempcorrect(n)
per = 100*ones(size(n)); % initial value 100
per(n >= 50) = 115;
per(n < 50 & n >= 40) = 108;
per(n < 40 & n >= 30) = 145;
per(n < 30 & n >= 20) = 120;
% not necessary if using 100 as initial value:
% per(n < 20) = 100;
% per(n < 20 & n >= 10) = 95;
% per(n < 10 & n >= 0) = 87;
% per(n < 0 & n >= -10) = 85;
% per(n < -10 & n >= -20) = 90;
% per(n < -20 & n >= -30) = 105;
% not necessary if using 100 as initial value:
% per(n < -30) = 100;
end
