Checking whether an object in space is a square

See Section 26.15.8 for checking for squares in 2D geometry.

The is_square command determines whether or not a geometric object is a square.

is_square takes G, a geometric object or a sequence of four points assumed to be the vertices of a quadrilateral.
is_square(G) returns 1 if the object is a square and returns 0 otherwise.

is_square([2,2,0],[-2,2,0],[-2,-2,0],[2,-2,0])

S:=square([0,0,0],[2,0,0],[0,0,1]); is_square(S)

is_square([2,2,0],[-2,2,0],[-2,-1,0],[2,-1,0])