Why do I get this error when multiplying two 2 vectors in MATLAB?

alpha =
     1    1    1    1    1    1    1    1    1

f_uv =
   193  193  194  192  193  193  190  189  191

alphaf_uv = alpha * f_uv'

"??? Error using ==> mtimes
Integers can only be combined with integers of the same class, or scalar doubles."

alphaf_uv = double(alpha) * double(f_uv')