void setup() 
{
  Serial.begin(115200);

  Serial.println("Formula: 1/round(pi/2)");

  Serial.print("1/round(pi/2)   :");
  Serial.println(1/round(M_PI/2));
  Serial.print("1/((int)pi/2)   :");
  Serial.println(1/((int)M_PI/2));
  Serial.print("1/int(pi/2)     :");
  Serial.println(1/int(M_PI/2));
  Serial.print("1/ceil(pi/2)    :");
  Serial.println(1/(ceil(M_PI/2)));
  Serial.print("1/floor(pi/2)   :");
  Serial.println((1/floor(M_PI/2)));
  Serial.print("float is good 1 :");
  Serial.println(1.0/round(M_PI/2));

#undef round
  Serial.print("undef round     :");
  Serial.println(1/round(M_PI/2));

  Serial.print("float is good 2 :");
  Serial.println(1.0/round(M_PI/2));
}

void loop() 
{
}