%!PS

/dotproduct {
    /b exch def
    /a exch def
    /p 0 def
    0 1 a length 1 sub {
        dup a exch get exch b exch get mul p add /p exch def
    } for
    p
} bind def

[ 1 2 3 ] [ 4 5 6 ] dotproduct 32 eq { (Pass) } { (FAIL) } ifelse =