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

t r(t) 2 -5 3 2 4 6 5 -10 6 -3 7 -3 8 7

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