void setup() 
{
   float x;

  for (x = 0; x < 2*PI; x += 0.1) {
    float result = cos(x);
    Serial.print("x = ");
    Serial.print(x);
    Serial.print(", cos(x) = ");
    Serial.println(result);
  }
}

void loop() {
  float x;

  for (x = 0; x < 2*PI; x += 0.1) {
    float result = cos(x);
    Serial.print("x = ");
    Serial.print(x);
    Serial.print(", cos(x) = ");
    Serial.println(result);
  }

}