If you declare an array double list $=\{3\mathrm{.}4,2\mathrm{.}0,3\mathrm{.}5,5\mathrm{.}5\},$ list $1$ is

$3\mathrm{.}4$

$2\mathrm{.}0$

$3\mathrm{.}5$

$5\mathrm{.}5$

undefined