Vectors

Can vectors grow? i know they can in matlab but in breve/steve?

i.e. if i wanted to build up a record of the positions that an agent moved to over time... so the vector would build u like this:

{x0, y0, z0}
{x0, y0, z0, x1, y1, z1}
{x0, y0, z0, x1, y1, z1, x2, y2, z2}

or would it be best to just use a list of vectors?

thanks
t