float[] data = {19.0, 40.0, 75.0, 76.0, 90.0};

void setup() {
  halve(data);
  println(data[0]); // Prints "9.5"
  println(data[1]); // Prints "20.0"
  println(data[2]); // Prints "37.5"
  println(data[3]); // Prints "38.0"
  println(data[4]); // Prints "45.0"
}
void halve(float[] d) {
  for (int i = 0; i < d.length; i++) { // For each array element,
    d[i] = d[i] / 2.0; // divide the value by 2
  }
}