Low-Pass Filter

α  is the sensor-believing value

x is the measurement value

y is the answer value

y[i] := α * x[i] + (1-α) * y[i-1]

 

float smooth(float data, float filterVal, float smoothedVal)

{

  smoothedVal = (data * (1 - filterVal)) + (smoothedVal * filterVal);

  return smoothedVal;

}

 

https://en.wikipedia.org/wiki/Low-pass_filter