Average Error: 3.4 → 2.2
Time: 4.7m
Precision: 64
Internal Precision: 128
\[\frac{\frac{\frac{\left(\left(\alpha + \beta\right) + \beta \cdot \alpha\right) + 1.0}{\left(\alpha + \beta\right) + 2 \cdot 1}}{\left(\alpha + \beta\right) + 2 \cdot 1}}{\left(\left(\alpha + \beta\right) + 2 \cdot 1\right) + 1.0}\]
\[\begin{array}{l} \mathbf{if}\;\beta \le 1.620987782235559 \cdot 10^{+142}:\\ \;\;\;\;\frac{\frac{\frac{1.0 + (\beta \cdot \alpha + \left(\beta + \alpha\right))_*}{\left(\beta + \alpha\right) + 2}}{\left(\beta + \alpha\right) + 2}}{\left(1.0 + \left(\beta + \alpha\right)\right) + 2}\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{\frac{\frac{2.0}{\beta} - 1.0}{\beta} + 1}{\left(\beta + \alpha\right) + 2}}{\left(1.0 + \left(\beta + \alpha\right)\right) + 2}\\ \end{array}\]

Error

Bits error versus alpha

Bits error versus beta

Derivation

  1. Split input into 2 regimes
  2. if beta < 1.620987782235559e+142

    1. Initial program 0.9

      \[\frac{\frac{\frac{\left(\left(\alpha + \beta\right) + \beta \cdot \alpha\right) + 1.0}{\left(\alpha + \beta\right) + 2 \cdot 1}}{\left(\alpha + \beta\right) + 2 \cdot 1}}{\left(\left(\alpha + \beta\right) + 2 \cdot 1\right) + 1.0}\]
    2. Simplified0.9

      \[\leadsto \color{blue}{\frac{\frac{\frac{1.0 + (\beta \cdot \alpha + \left(\beta + \alpha\right))_*}{2 + \left(\beta + \alpha\right)}}{2 + \left(\beta + \alpha\right)}}{\left(1.0 + \left(\beta + \alpha\right)\right) + 2}}\]
    3. Using strategy rm
    4. Applied +-commutative0.9

      \[\leadsto \frac{\frac{\frac{1.0 + (\beta \cdot \alpha + \left(\beta + \alpha\right))_*}{2 + \left(\beta + \alpha\right)}}{2 + \left(\beta + \alpha\right)}}{\color{blue}{2 + \left(1.0 + \left(\beta + \alpha\right)\right)}}\]

    if 1.620987782235559e+142 < beta

    1. Initial program 15.3

      \[\frac{\frac{\frac{\left(\left(\alpha + \beta\right) + \beta \cdot \alpha\right) + 1.0}{\left(\alpha + \beta\right) + 2 \cdot 1}}{\left(\alpha + \beta\right) + 2 \cdot 1}}{\left(\left(\alpha + \beta\right) + 2 \cdot 1\right) + 1.0}\]
    2. Simplified15.3

      \[\leadsto \color{blue}{\frac{\frac{\frac{1.0 + (\beta \cdot \alpha + \left(\beta + \alpha\right))_*}{2 + \left(\beta + \alpha\right)}}{2 + \left(\beta + \alpha\right)}}{\left(1.0 + \left(\beta + \alpha\right)\right) + 2}}\]
    3. Using strategy rm
    4. Applied +-commutative15.3

      \[\leadsto \frac{\frac{\frac{1.0 + (\beta \cdot \alpha + \left(\beta + \alpha\right))_*}{2 + \left(\beta + \alpha\right)}}{2 + \left(\beta + \alpha\right)}}{\color{blue}{2 + \left(1.0 + \left(\beta + \alpha\right)\right)}}\]
    5. Taylor expanded around -inf 8.3

      \[\leadsto \frac{\frac{\color{blue}{\left(2.0 \cdot \frac{1}{{\beta}^{2}} + 1\right) - 1.0 \cdot \frac{1}{\beta}}}{2 + \left(\beta + \alpha\right)}}{2 + \left(1.0 + \left(\beta + \alpha\right)\right)}\]
    6. Simplified8.3

      \[\leadsto \frac{\frac{\color{blue}{1 + \frac{\frac{2.0}{\beta} - 1.0}{\beta}}}{2 + \left(\beta + \alpha\right)}}{2 + \left(1.0 + \left(\beta + \alpha\right)\right)}\]
  3. Recombined 2 regimes into one program.
  4. Final simplification2.2

    \[\leadsto \begin{array}{l} \mathbf{if}\;\beta \le 1.620987782235559 \cdot 10^{+142}:\\ \;\;\;\;\frac{\frac{\frac{1.0 + (\beta \cdot \alpha + \left(\beta + \alpha\right))_*}{\left(\beta + \alpha\right) + 2}}{\left(\beta + \alpha\right) + 2}}{\left(1.0 + \left(\beta + \alpha\right)\right) + 2}\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{\frac{\frac{2.0}{\beta} - 1.0}{\beta} + 1}{\left(\beta + \alpha\right) + 2}}{\left(1.0 + \left(\beta + \alpha\right)\right) + 2}\\ \end{array}\]

Reproduce

herbie shell --seed 2019089 +o rules:numerics
(FPCore (alpha beta)
  :name "Octave 3.8, jcobi/3"
  :pre (and (> alpha -1) (> beta -1))
  (/ (/ (/ (+ (+ (+ alpha beta) (* beta alpha)) 1.0) (+ (+ alpha beta) (* 2 1))) (+ (+ alpha beta) (* 2 1))) (+ (+ (+ alpha beta) (* 2 1)) 1.0)))