### Thursday, 2014-09-18

## Easing Functions

**Cubic** uses the equation ```
y = -2kx^3 + 3kx^2 +
(1-k)x
```

. It has fairly limited easing.

**x/|x| sigmoid** uses the equation ```
y = x / (1 + k*(abs(x)
- 1))
```

(and its inverse `(1+k)*x / (1 + k*abs(x))`

for
negative `k`

). It goes all the way to a full step function
in both directions.