Function invlerp

invlerp(x, y, a): number
Performs inverse linear interpolation.

This function returns the normalized value of a in the range [x, y]. It calculates how far a is between x and y and returns a value between 0 and 1.
Parameters
- x: number
  The start of the range.
- y: number
  The end of the range.
- a: number
  The value to normalize, which should lie between x and y.
Returns number
A normalized value between 0 and 1 that represents where a lies between x and y.