Shoelace formula for polygonal area: Difference between revisions

=={{header|Nim}}==

<lang nim>import math

type

Point = tuple

x: float

y: float

func shoelace(points: openArray[Point]): float =

var leftSum, rightSum = 0.0

for i in 0..<len(points):

var j = (i + 1) mod len(points)

leftSum += points[i].x * points[j].y

rightSum += points[j].x * points[i].y

0.5 * abs(leftSum - rightSum)

var points = [(3.0, 4.0), (5.0, 11.0), (12.0, 8.0), (9.0, 5.0), (5.0, 6.0)]

echo $shoelace(points)</lang>

{{out}}

<pre>

30.0

</pre>