..lowPass highPass methods

// de-emphasize transient forces
private float lowPass(float current, float gravity) {
// ALPHA indicates the influence level of past observations
  return current * (1-ALPHA) + gravity * ALPHA; 
}

// de-emphasize constant forces
private float highPass(float current, float gravity) {
  return current - gravity;
}
    
private boolean inRange(float value, float target,  float tol) {
  return value >= target-tol && value <= target+tol;
}