MATLAB: Unfamiliar Vector Index Notation

vector indexing

I recently encountered code that addresses a vector as V(a:b:c). Not sure what this does. I am used to V(a:b).

Then somefunction.m does not take input arguments for example:

function x = somefunction
x = 2;
end

if you call

x = somefunction()

you get x = 2

you can also just enter

x = somefunction;

A(setdiff(1:numel(A),index))