Average Error: 58.7 → 1.1
Time: 1.8m
Precision: 64
Internal Precision: 2368
\[\frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\]
\[\begin{array}{l} \mathbf{if}\;\frac{1}{a} + \frac{1}{b} \le -2.5982032350689694 \cdot 10^{-18} \lor \neg \left(\frac{1}{a} + \frac{1}{b} \le 6.537931662863092 \cdot 10^{-55}\right):\\ \;\;\;\;\frac{1}{a} + \frac{1}{b}\\ \mathbf{else}:\\ \;\;\;\;\frac{(e^{\varepsilon \cdot \left(a + b\right)} - 1)^*}{(e^{(b \cdot \left(\varepsilon + \varepsilon\right) + \left(\varepsilon \cdot b\right))_*} - 1)^* \cdot \frac{(e^{a \cdot \varepsilon} - 1)^*}{\varepsilon}} \cdot \left(\left(e^{\varepsilon \cdot b} + 1\right) + e^{\varepsilon \cdot b} \cdot e^{\varepsilon \cdot b}\right)\\ \end{array}\]

Error

Bits error versus a

Bits error versus b

Bits error versus eps

Target

Original58.7
Target14.7
Herbie1.1
\[\frac{a + b}{a \cdot b}\]

Derivation

  1. Split input into 2 regimes
  2. if (+ (/ 1 b) (/ 1 a)) < -2.5982032350689694e-18 or 6.537931662863092e-55 < (+ (/ 1 b) (/ 1 a))

    1. Initial program 61.9

      \[\frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\]
    2. Taylor expanded around 0 0.2

      \[\leadsto \color{blue}{\frac{1}{b} + \frac{1}{a}}\]

    if -2.5982032350689694e-18 < (+ (/ 1 b) (/ 1 a)) < 6.537931662863092e-55

    1. Initial program 42.8

      \[\frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}\]
    2. Using strategy rm
    3. Applied flip3--46.9

      \[\leadsto \frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \color{blue}{\frac{{\left(e^{b \cdot \varepsilon}\right)}^{3} - {1}^{3}}{e^{b \cdot \varepsilon} \cdot e^{b \cdot \varepsilon} + \left(1 \cdot 1 + e^{b \cdot \varepsilon} \cdot 1\right)}}}\]
    4. Applied associate-*r/46.9

      \[\leadsto \frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\color{blue}{\frac{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left({\left(e^{b \cdot \varepsilon}\right)}^{3} - {1}^{3}\right)}{e^{b \cdot \varepsilon} \cdot e^{b \cdot \varepsilon} + \left(1 \cdot 1 + e^{b \cdot \varepsilon} \cdot 1\right)}}}\]
    5. Applied associate-/r/46.9

      \[\leadsto \color{blue}{\frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left({\left(e^{b \cdot \varepsilon}\right)}^{3} - {1}^{3}\right)} \cdot \left(e^{b \cdot \varepsilon} \cdot e^{b \cdot \varepsilon} + \left(1 \cdot 1 + e^{b \cdot \varepsilon} \cdot 1\right)\right)}\]
    6. Applied simplify5.6

      \[\leadsto \color{blue}{\frac{(e^{\left(a + b\right) \cdot \varepsilon} - 1)^*}{(e^{(b \cdot \left(\varepsilon + \varepsilon\right) + \left(\varepsilon \cdot b\right))_*} - 1)^* \cdot \frac{(e^{a \cdot \varepsilon} - 1)^*}{\varepsilon}}} \cdot \left(e^{b \cdot \varepsilon} \cdot e^{b \cdot \varepsilon} + \left(1 \cdot 1 + e^{b \cdot \varepsilon} \cdot 1\right)\right)\]
  3. Recombined 2 regimes into one program.
  4. Applied simplify1.1

    \[\leadsto \color{blue}{\begin{array}{l} \mathbf{if}\;\frac{1}{a} + \frac{1}{b} \le -2.5982032350689694 \cdot 10^{-18} \lor \neg \left(\frac{1}{a} + \frac{1}{b} \le 6.537931662863092 \cdot 10^{-55}\right):\\ \;\;\;\;\frac{1}{a} + \frac{1}{b}\\ \mathbf{else}:\\ \;\;\;\;\frac{(e^{\varepsilon \cdot \left(a + b\right)} - 1)^*}{(e^{(b \cdot \left(\varepsilon + \varepsilon\right) + \left(\varepsilon \cdot b\right))_*} - 1)^* \cdot \frac{(e^{a \cdot \varepsilon} - 1)^*}{\varepsilon}} \cdot \left(\left(e^{\varepsilon \cdot b} + 1\right) + e^{\varepsilon \cdot b} \cdot e^{\varepsilon \cdot b}\right)\\ \end{array}}\]

Runtime

Time bar (total: 1.8m)Debug logProfile

herbie shell --seed '#(1072840222 1305617769 1692503039 1353360431 4178980589 1488672652)' +o rules:numerics
(FPCore (a b eps)
  :name "expq3 (problem 3.4.2)"
  :pre (and (< -1 eps) (< eps 1))

  :herbie-target
  (/ (+ a b) (* a b))

  (/ (* eps (- (exp (* (+ a b) eps)) 1)) (* (- (exp (* a eps)) 1) (- (exp (* b eps)) 1))))