Average Error: 29.8 → 0.0
Time: 20.6s
Precision: 64
\[\log \left(N + 1\right) - \log N\]
\[\begin{array}{l} \mathbf{if}\;N \le 8873.677015963014:\\ \;\;\;\;\log \left(\frac{1 + N}{N}\right)\\ \mathbf{else}:\\ \;\;\;\;\left(\frac{1}{N} + \frac{\frac{-1}{2}}{N \cdot N}\right) + \frac{\frac{\frac{1}{3}}{N \cdot N}}{N}\\ \end{array}\]
double f(double N) {
        double r1890987 = N;
        double r1890988 = 1.0;
        double r1890989 = r1890987 + r1890988;
        double r1890990 = log(r1890989);
        double r1890991 = log(r1890987);
        double r1890992 = r1890990 - r1890991;
        return r1890992;
}

double f(double N) {
        double r1890993 = N;
        double r1890994 = 8873.677015963014;
        bool r1890995 = r1890993 <= r1890994;
        double r1890996 = 1.0;
        double r1890997 = r1890996 + r1890993;
        double r1890998 = r1890997 / r1890993;
        double r1890999 = log(r1890998);
        double r1891000 = r1890996 / r1890993;
        double r1891001 = -0.5;
        double r1891002 = r1890993 * r1890993;
        double r1891003 = r1891001 / r1891002;
        double r1891004 = r1891000 + r1891003;
        double r1891005 = 0.3333333333333333;
        double r1891006 = r1891005 / r1891002;
        double r1891007 = r1891006 / r1890993;
        double r1891008 = r1891004 + r1891007;
        double r1891009 = r1890995 ? r1890999 : r1891008;
        return r1891009;
}

\log \left(N + 1\right) - \log N
\begin{array}{l}
\mathbf{if}\;N \le 8873.677015963014:\\
\;\;\;\;\log \left(\frac{1 + N}{N}\right)\\

\mathbf{else}:\\
\;\;\;\;\left(\frac{1}{N} + \frac{\frac{-1}{2}}{N \cdot N}\right) + \frac{\frac{\frac{1}{3}}{N \cdot N}}{N}\\

\end{array}

Error

Bits error versus N

Derivation

  1. Split input into 2 regimes
  2. if N < 8873.677015963014

    1. Initial program 0.1

      \[\log \left(N + 1\right) - \log N\]
    2. Using strategy rm
    3. Applied diff-log0.1

      \[\leadsto \color{blue}{\log \left(\frac{N + 1}{N}\right)}\]

    if 8873.677015963014 < N

    1. Initial program 59.5

      \[\log \left(N + 1\right) - \log N\]
    2. Taylor expanded around -inf 0.0

      \[\leadsto \color{blue}{\left(\frac{1}{3} \cdot \frac{1}{{N}^{3}} + \frac{1}{N}\right) - \frac{1}{2} \cdot \frac{1}{{N}^{2}}}\]
    3. Simplified0.0

      \[\leadsto \color{blue}{\left(\frac{1}{N} + \frac{\frac{-1}{2}}{N \cdot N}\right) + \frac{\frac{\frac{1}{3}}{N \cdot N}}{N}}\]
  3. Recombined 2 regimes into one program.
  4. Final simplification0.0

    \[\leadsto \begin{array}{l} \mathbf{if}\;N \le 8873.677015963014:\\ \;\;\;\;\log \left(\frac{1 + N}{N}\right)\\ \mathbf{else}:\\ \;\;\;\;\left(\frac{1}{N} + \frac{\frac{-1}{2}}{N \cdot N}\right) + \frac{\frac{\frac{1}{3}}{N \cdot N}}{N}\\ \end{array}\]

Reproduce

herbie shell --seed 2019101 
(FPCore (N)
  :name "2log (problem 3.3.6)"
  (- (log (+ N 1)) (log N)))