$x = @(1, 2, 3, 1e11)
$y = @(1, 1.4142135623730951, 1.7320508075688772, 316227.76601683791)
$xprecision = 3
$yprecision = 5
$arr = foreach($i in 0..($x.count-1)) {
    [pscustomobject]@{x = "{0:g$xprecision}"  -f $x[$i]; y = "{0:g$yprecision}" -f $y[$i]}
}
($arr | format-table -HideTableHeaders | Out-String).Trim() > filename.txt