Is $\displaystyle {r}{\left({t}\right)}$ represented in the table below a function?

t r(t) 0 5 1 0 2 -3 3 7 4 -9 5 8 6 -2

$\displaystyle {r}{\left({t}\right)}$ is not a function $\displaystyle {r}{\left({t}\right)}$ is a function