Shoelace formula for polygonal area: Difference between revisions

# Even simpler:

# In python we can take an advantage of that x[-1] refers to the last element in an array, same as x[N-1].

# Thus x[i] is a sequence of the x-coordinate of the polygon vertices, x[i-1] is the sequence shifted by 1 index.

# Note that the shift must be negative. The positive shift x[i+1] results in an error: x[N] index out of bound.