lowpass fillter

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(A0, INPUT);
}

float u, y;
int p = 0;
void loop() {
  u = (float)analogRead(0) * 5;
  u = (u / 1024) * 3.059;

  y = 0.945 * y + 0.05498 * u;

  // p = y * 100 / 4.19;
  p = (y - 2.75) * 100.0 / (4.19 - 2.75);

  Serial.print(p);
  Serial.print("\t");
  Serial.print(y);
  Serial.println();
  delay(350);
}