const int pinled = 13;
const int pinldr = 2;

// LDR Characteristics
const float GAMMA = 0.7;
const float RL10 = 50;

void setup() {
  // put your setup code here, to run once:
  pinMode(pinled, OUTPUT);
  pinMode(pinldr, INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  int analogValue = analogRead(A0);
  float voltage = analogValue / 1024. * 5;
  float resistance = 2000 * voltage / (1 - voltage / 5);
  float lux = pow(RL10 * 1e3 * pow(10, GAMMA) / resistance, (1 / GAMMA));

  if (lux > 50) {
    digitalWrite(pinled,HIGH);
  } else {
   digitalWrite(pinled,LOW);
  }

}