Setting optional parameters in easing functions

I'd like to tune the behavior of an easing function, but the 'amplitude' tunable parameter doesn't seem to do anything.

I'm using outElastic, which according to the documentation has optional arguments a (amplitude), and p (period). The default bounce is too bouncy, so wanted to try adjusting a to tone the bounce down.

The documentation wasn't super clear for how to set a, but I found examples in /PlaydateSDK/Examples/Single File Examples/animator.lua where similar tunable parameters were set for easing functions. In those examples the optional arguments are set after declaring the animator (see example below for repeatCount):

local parts = {topArc3, rightLine3, bottomArc3, leftLine3}
local spriteAnimation =, parts, playdate.easingFunctions.linear)
spriteAnimation.repeatCount = -1

I tried to copy that approach like this:

local _easing = pd.easingFunctions.outElastic
self.animator =, self.x, self.target_x, _easing)
self.animator.easingAmplitude = 1000

But no matter what extreme values I try for the amplitude the in-game behavior seems the same. Am I doing this right?

Running Linux (Ubuntu 22.04)