Calculate a smooth interpolation percentage of
The function receives the number
x as an argument and returns 0 if
x is less than or equal to the left edge,
x is greater than or equal to the right edge, and smoothly interpolates, using a Hermite polynomial,
between 0 and 1 otherwise.
The input value.
The minimum value, also known as the 'left edge', assumed smaller than the 'right edge'.
The maximum value, also known as the 'right edge', assumed greater than the 'left edge'.
The percentage of interpolation, between 0 and 1.