real mapRange(int s, int a1, int a2, int b1, int b2) {
  return b1 + (s - a1) * (b2 - b1) / (a2 - a1);
}

for (int i = 0; i <= 10; ++i) {
  real r = mapRange(i, 0, 10, -1, 0);
  write( (string)i + " maps to " + format("%0.1f", r) );
}