The only change you temporatily need to make is to create your function as a character vector by putting single quotes (') around it first, then removing them from the vectorize output.
f = exp(-0.1*t) * sin(2*pi*t);
fv = vectorize('exp(-0.1*t) * sin(2*pi*t)')
'exp(-0.1.*t) .* sin(2.*pi.*t)'
You then have to manually edit your expression to put it back as a valid expression. That simply means removing the single quotes:
f = exp(-0.1.*t) .* sin(2.*pi.*t)
and your expression is vectorized, ready for your linspace arguments!
EDIT — Corrected typographical errors.