distance
Calculates the Euclidean distance between two 4D vectors, a and b.
The distance is computed as the square root of the sum of the squared differences between their corresponding components: sqrt((a.x-b.x)^2 + (a.y-b.y)^2 + (a.z-b.z)^2 + (a.w-b.w)^2).
Return
The Euclidean distance between the two vectors as a Float.