Using for loops to check elements

I have vector a=[1 2 4 4 2 1] and I want to create a for loop that does some calculations between each element of a, i.e. it performs the calculations between 1 and 2, then between 2 and 4, then between 4 and 4, 4 and 2, then 2 and 1. How can I do this? Thanks.

[Guillaume]

It might be entirely possible that the loop is not needed. Details of the calculations would be required to know for sure.

E.g if you just wanted to do 3*a(i)-2*a(i+1)^2, this would simply be:

result = 3*a(1:end-1) - 2*a(2:end).^2

Answer 1

[Bruno Luong]

for i=1:length(a)-1
  interval = a([i i+1]);
  dosomething(interval);
end