easeInOutQuad

The quadratic ease in and out of t in [0, 1]: slow at both ends, 0.5 at the middle, 0 at 0 and 1 at 1. This is the .QUADRIC shape.

assert(easeInOutQuad(0) == 0 && easeInOutQuad(1) == 1 && easeInOutQuad(0.5) == 0.5);
assert(easeInOutQuad(0.25) == 0.125);

easeInOutQuad :: (t: float) -> float