Is there a way to find the index of a subsection of a vector?

Lets say I have the vector

a = [1,2,1,2,3,4,5,1,2,1];

and I need to search through it to find:

b = [1,2];

and get the output which shows me the indexes of where the start of each b is.

i.e.

out = [1, 3, 8];

Any help would be appreciated

Answer 1

[David Haydock]

strfind