Consider the following recursive Java function $f$ that takes two long arguments and returns a float value:

public static float f (long m, long n) {
float result = (float)m / (float)n;
if (m < 0 || n<0) return 0.0f;
else result -=f(m*2, n*3);
return result;
}

Which of the following real values best approximates the value of $f(1,3)$?