square()

double square(double x);

void setup() {
    pinLabel(0, "IN");   // set the label of pin 0 to "IN"
    pinLabel(1, "OUT");  // set the label of pin 1 to "OUT"
    pinMode(1, OUTPUT);  // set pin 1 as output
    pinLabel(2, "VCC");  // set the label of pin 2 to "VCC"
    powerPin(2);         // set pin 2 as power pin
    pinLabel(3, "GND");  // set the label of pin 3 to "GND"
    groundPin(3);        // set pin 3 as ground pin
}
void loop() {
    int val = analogRead(0); // read the value of the potentiometer
    double x = map(val, 0, 1023, 0, 5); // map the value
    double y = square(x); // calculate the square value of x
    int pwm = (int) map(y, 0, 25, 0, 1023); // map the value
    analogWrite(1, pwm); // write the value of pwm to pin 1
}