how to remove odds from a dataset

have a dataset that contains a1,a2,a3,a4,a5,b1,b2,b3,b4,b5..etc how do I delete the odds so it can only have a2, a4, b2, b4 etc...

[Azzi Abdelmalek]

Duplicate

Answer 1

[Azzi Abdelmalek]

v=[1 2 3 4 5 6 7 8]
out=v(2:2:end)