Average Error: 29.6 → 0.9
Time: 3.5m
Precision: 64
Internal Precision: 1344
\[\frac{\left(1 + \frac{1}{\varepsilon}\right) \cdot e^{-\left(1 - \varepsilon\right) \cdot x} - \left(\frac{1}{\varepsilon} - 1\right) \cdot e^{-\left(1 + \varepsilon\right) \cdot x}}{2}\]
\[\begin{array}{l} \mathbf{if}\;x \le 400.2976489691012:\\ \;\;\;\;\frac{\frac{8 + \left(8 \cdot {x}^{3} + \frac{5}{3} \cdot {x}^{6}\right)}{\left(x \cdot x\right) \cdot \left(x \cdot x\right) + \left(\left(x \cdot x + 2\right) + \left(x \cdot x\right) \cdot \left(x \cdot \frac{2}{3}\right)\right) \cdot \left(2 + \left(x \cdot x\right) \cdot \left(x \cdot \frac{2}{3}\right)\right)}}{2}\\ \mathbf{else}:\\ \;\;\;\;\frac{\left(1 + \frac{1}{\varepsilon}\right) \cdot e^{-\left(1 - \varepsilon\right) \cdot x} - \left(\left(\frac{1}{\varepsilon} - 1\right) \cdot \sqrt{e^{-\left(1 + \varepsilon\right) \cdot x}}\right) \cdot \sqrt{e^{-\left(1 + \varepsilon\right) \cdot x}}}{2}\\ \end{array}\]

Error

Bits error versus x

Bits error versus eps

Derivation

  1. Split input into 2 regimes
  2. if x < 400.2976489691012

    1. Initial program 39.6

      \[\frac{\left(1 + \frac{1}{\varepsilon}\right) \cdot e^{-\left(1 - \varepsilon\right) \cdot x} - \left(\frac{1}{\varepsilon} - 1\right) \cdot e^{-\left(1 + \varepsilon\right) \cdot x}}{2}\]
    2. Taylor expanded around 0 1.1

      \[\leadsto \frac{\color{blue}{\left(2 + \frac{2}{3} \cdot {x}^{3}\right) - {x}^{2}}}{2}\]
    3. Using strategy rm
    4. Applied add-log-exp1.2

      \[\leadsto \frac{\left(2 + \color{blue}{\log \left(e^{\frac{2}{3} \cdot {x}^{3}}\right)}\right) - {x}^{2}}{2}\]
    5. Using strategy rm
    6. Applied flip3--1.2

      \[\leadsto \frac{\color{blue}{\frac{{\left(2 + \log \left(e^{\frac{2}{3} \cdot {x}^{3}}\right)\right)}^{3} - {\left({x}^{2}\right)}^{3}}{\left(2 + \log \left(e^{\frac{2}{3} \cdot {x}^{3}}\right)\right) \cdot \left(2 + \log \left(e^{\frac{2}{3} \cdot {x}^{3}}\right)\right) + \left({x}^{2} \cdot {x}^{2} + \left(2 + \log \left(e^{\frac{2}{3} \cdot {x}^{3}}\right)\right) \cdot {x}^{2}\right)}}}{2}\]
    7. Applied simplify1.2

      \[\leadsto \frac{\frac{{\left(2 + \log \left(e^{\frac{2}{3} \cdot {x}^{3}}\right)\right)}^{3} - {\left({x}^{2}\right)}^{3}}{\color{blue}{\left(x \cdot x\right) \cdot \left(x \cdot x\right) + \left(\left(x \cdot x + 2\right) + \left(x \cdot x\right) \cdot \left(x \cdot \frac{2}{3}\right)\right) \cdot \left(2 + \left(x \cdot x\right) \cdot \left(x \cdot \frac{2}{3}\right)\right)}}}{2}\]
    8. Taylor expanded around 0 1.2

      \[\leadsto \frac{\frac{\color{blue}{8 + \left(8 \cdot {x}^{3} + \frac{5}{3} \cdot {x}^{6}\right)}}{\left(x \cdot x\right) \cdot \left(x \cdot x\right) + \left(\left(x \cdot x + 2\right) + \left(x \cdot x\right) \cdot \left(x \cdot \frac{2}{3}\right)\right) \cdot \left(2 + \left(x \cdot x\right) \cdot \left(x \cdot \frac{2}{3}\right)\right)}}{2}\]

    if 400.2976489691012 < x

    1. Initial program 0.0

      \[\frac{\left(1 + \frac{1}{\varepsilon}\right) \cdot e^{-\left(1 - \varepsilon\right) \cdot x} - \left(\frac{1}{\varepsilon} - 1\right) \cdot e^{-\left(1 + \varepsilon\right) \cdot x}}{2}\]
    2. Using strategy rm
    3. Applied add-sqr-sqrt0.0

      \[\leadsto \frac{\left(1 + \frac{1}{\varepsilon}\right) \cdot e^{-\left(1 - \varepsilon\right) \cdot x} - \left(\frac{1}{\varepsilon} - 1\right) \cdot \color{blue}{\left(\sqrt{e^{-\left(1 + \varepsilon\right) \cdot x}} \cdot \sqrt{e^{-\left(1 + \varepsilon\right) \cdot x}}\right)}}{2}\]
    4. Applied associate-*r*0.0

      \[\leadsto \frac{\left(1 + \frac{1}{\varepsilon}\right) \cdot e^{-\left(1 - \varepsilon\right) \cdot x} - \color{blue}{\left(\left(\frac{1}{\varepsilon} - 1\right) \cdot \sqrt{e^{-\left(1 + \varepsilon\right) \cdot x}}\right) \cdot \sqrt{e^{-\left(1 + \varepsilon\right) \cdot x}}}}{2}\]
  3. Recombined 2 regimes into one program.

Runtime

Time bar (total: 3.5m)Debug logProfile

herbie shell --seed '#(1071725047 233389029 2036512464 3988615230 2972226563 1111574017)' 
(FPCore (x eps)
  :name "NMSE Section 6.1 mentioned, A"
  (/ (- (* (+ 1 (/ 1 eps)) (exp (- (* (- 1 eps) x)))) (* (- (/ 1 eps) 1) (exp (- (* (+ 1 eps) x))))) 2))