what is the index variable

 Consider the execution of the following MATLAB code:

a = 11;
b = 4;
z = 5:5:25;
for k = a:-1:b
if k > 5
z = z - 5;  %
elseif k == 3
z = z - 10;  %
else
z = z - 4;  %
end
end  %

% Which is the loop index variable?

Answer 1

[Stephen23]

k is the loop index variable in the code that you showed. The loop index variable is always defined after for:

for ??? = ...
     ^ this is where the loop index available is specified.

This is also shown in the MATLAB documentation:

https://www.mathworks.com/help/matlab/ref/for.html