PROC y := P(x) IS 
  VAR scale = 1 IN 
    IF 
      x > 1 -> 
        DO 
          x > 1 -> 
            x := x / 4; 
            scale := scale * 2 
        OD 
    | x < 1 / 4 -> 
        DO 
          x < 1 / 4 -> 
            x := x * 4; 
            scale := scale / 2 
        OD 
    FI; 
    IF 
      VAR sqrt ~ x IN 
        sqrt * sqrt = x -> 
          y := sqrt * scale 
      END 
    FI 
  END 
END;