ENA, Section 1.4, Exercise 4b, n=2

Percentage Accurate: 74.6% → 100.0%
Time: 5.2s
Alternatives: 5
Speedup: 69.0×

Specification

?
\[{\left(x + \varepsilon\right)}^{2} - {x}^{2} \]

Your Program's Arguments

Results

Enter valid numbers for all inputs

Local Percentage Accuracy vs ?

The average percentage accuracy by input value. Horizontal axis shows value of an input variable; the variable is choosen in the title. Vertical axis is accuracy; higher is better. Red represent the original program, while blue represents Herbie's suggestion. These can be toggled with buttons below the plot. The line is an average while dots represent individual samples.

Accuracy vs Speed?

Herbie found 5 alternatives:

AlternativeAccuracySpeedup
The accuracy (vertical axis) and speed (horizontal axis) of each alternatives. Up and to the right is better. The red square shows the initial program, and each blue circle shows an alternative.The line shows the best available speed-accuracy tradeoffs.

Alternative 1: 100.0% accurate, 29.6× speedup?

\[\varepsilon \cdot \left(x + \left(\varepsilon + x\right)\right) \]
Derivation
  1. Initial program 71.1%

    \[{\left(x + \varepsilon\right)}^{2} - {x}^{2} \]
  2. Step-by-step derivation
    1. unpow271.1%

      \[\leadsto {\left(x + \varepsilon\right)}^{2} - \color{blue}{x \cdot x} \]
  3. Simplified71.1%

    \[\leadsto \color{blue}{{\left(x + \varepsilon\right)}^{2} - x \cdot x} \]
  4. Step-by-step derivation
    1. unpow271.1%

      \[\leadsto \color{blue}{\left(x + \varepsilon\right) \cdot \left(x + \varepsilon\right)} - x \cdot x \]
    2. +-commutative71.1%

      \[\leadsto \left(x + \varepsilon\right) \cdot \color{blue}{\left(\varepsilon + x\right)} - x \cdot x \]
    3. +-commutative71.1%

      \[\leadsto \color{blue}{\left(\varepsilon + x\right)} \cdot \left(\varepsilon + x\right) - x \cdot x \]
  5. Applied egg-rr71.1%

    \[\leadsto \color{blue}{\left(\varepsilon + x\right) \cdot \left(\varepsilon + x\right)} - x \cdot x \]
  6. Step-by-step derivation
    1. distribute-rgt-in71.2%

      \[\leadsto \color{blue}{\left(\varepsilon \cdot \left(\varepsilon + x\right) + x \cdot \left(\varepsilon + x\right)\right)} - x \cdot x \]
    2. *-commutative71.2%

      \[\leadsto \left(\color{blue}{\left(\varepsilon + x\right) \cdot \varepsilon} + x \cdot \left(\varepsilon + x\right)\right) - x \cdot x \]
    3. associate--l+74.6%

      \[\leadsto \color{blue}{\left(\varepsilon + x\right) \cdot \varepsilon + \left(x \cdot \left(\varepsilon + x\right) - x \cdot x\right)} \]
    4. +-commutative74.6%

      \[\leadsto \color{blue}{\left(x \cdot \left(\varepsilon + x\right) - x \cdot x\right) + \left(\varepsilon + x\right) \cdot \varepsilon} \]
    5. distribute-lft-out--74.6%

      \[\leadsto \color{blue}{x \cdot \left(\left(\varepsilon + x\right) - x\right)} + \left(\varepsilon + x\right) \cdot \varepsilon \]
    6. +-commutative74.6%

      \[\leadsto x \cdot \left(\color{blue}{\left(x + \varepsilon\right)} - x\right) + \left(\varepsilon + x\right) \cdot \varepsilon \]
    7. *-commutative74.6%

      \[\leadsto x \cdot \left(\left(x + \varepsilon\right) - x\right) + \color{blue}{\varepsilon \cdot \left(\varepsilon + x\right)} \]
    8. +-commutative74.6%

      \[\leadsto x \cdot \left(\left(x + \varepsilon\right) - x\right) + \varepsilon \cdot \color{blue}{\left(x + \varepsilon\right)} \]
  7. Applied egg-rr74.6%

    \[\leadsto \color{blue}{x \cdot \left(\left(x + \varepsilon\right) - x\right) + \varepsilon \cdot \left(x + \varepsilon\right)} \]
  8. Taylor expanded in x around 0 99.9%

    \[\leadsto x \cdot \color{blue}{\varepsilon} + \varepsilon \cdot \left(x + \varepsilon\right) \]
  9. Step-by-step derivation
    1. +-commutative99.9%

      \[\leadsto \color{blue}{\varepsilon \cdot \left(x + \varepsilon\right) + x \cdot \varepsilon} \]
    2. *-commutative99.9%

      \[\leadsto \varepsilon \cdot \left(x + \varepsilon\right) + \color{blue}{\varepsilon \cdot x} \]
    3. distribute-lft-out100.0%

      \[\leadsto \color{blue}{\varepsilon \cdot \left(\left(x + \varepsilon\right) + x\right)} \]
  10. Applied egg-rr100.0%

    \[\leadsto \color{blue}{\varepsilon \cdot \left(\left(x + \varepsilon\right) + x\right)} \]
  11. Final simplification100.0%

    \[\leadsto \varepsilon \cdot \left(x + \left(\varepsilon + x\right)\right) \]

Alternative 2: 91.2% accurate, 22.6× speedup?

\[\begin{array}{l} \mathbf{if}\;x \leq -3.8 \cdot 10^{-96} \lor \neg \left(x \leq 1.15 \cdot 10^{-99}\right):\\ \;\;\;\;2 \cdot \left(\varepsilon \cdot x\right)\\ \mathbf{else}:\\ \;\;\;\;\varepsilon \cdot \varepsilon\\ \end{array} \]
Derivation
  1. Split input into 2 regimes
  2. if x < -3.8000000000000001e-96 or 1.1499999999999999e-99 < x

    1. Initial program 35.9%

      \[{\left(x + \varepsilon\right)}^{2} - {x}^{2} \]
    2. Step-by-step derivation
      1. unpow235.9%

        \[\leadsto \color{blue}{\left(x + \varepsilon\right) \cdot \left(x + \varepsilon\right)} - {x}^{2} \]
      2. unpow235.9%

        \[\leadsto \left(x + \varepsilon\right) \cdot \left(x + \varepsilon\right) - \color{blue}{x \cdot x} \]
      3. difference-of-squares35.8%

        \[\leadsto \color{blue}{\left(\left(x + \varepsilon\right) + x\right) \cdot \left(\left(x + \varepsilon\right) - x\right)} \]
      4. *-commutative35.8%

        \[\leadsto \color{blue}{\left(\left(x + \varepsilon\right) - x\right) \cdot \left(\left(x + \varepsilon\right) + x\right)} \]
      5. +-commutative35.8%

        \[\leadsto \left(\color{blue}{\left(\varepsilon + x\right)} - x\right) \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      6. associate--l+99.9%

        \[\leadsto \color{blue}{\left(\varepsilon + \left(x - x\right)\right)} \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      7. +-inverses99.9%

        \[\leadsto \left(\varepsilon + \color{blue}{0}\right) \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      8. +-rgt-identity99.9%

        \[\leadsto \color{blue}{\varepsilon} \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      9. +-commutative99.9%

        \[\leadsto \varepsilon \cdot \color{blue}{\left(x + \left(x + \varepsilon\right)\right)} \]
      10. associate-+r+99.9%

        \[\leadsto \varepsilon \cdot \color{blue}{\left(\left(x + x\right) + \varepsilon\right)} \]
      11. count-299.9%

        \[\leadsto \varepsilon \cdot \left(\color{blue}{2 \cdot x} + \varepsilon\right) \]
      12. fma-def99.9%

        \[\leadsto \varepsilon \cdot \color{blue}{\mathsf{fma}\left(2, x, \varepsilon\right)} \]
    3. Simplified99.9%

      \[\leadsto \color{blue}{\varepsilon \cdot \mathsf{fma}\left(2, x, \varepsilon\right)} \]
    4. Taylor expanded in eps around 0 86.4%

      \[\leadsto \color{blue}{2 \cdot \left(\varepsilon \cdot x\right)} \]

    if -3.8000000000000001e-96 < x < 1.1499999999999999e-99

    1. Initial program 96.9%

      \[{\left(x + \varepsilon\right)}^{2} - {x}^{2} \]
    2. Step-by-step derivation
      1. unpow296.9%

        \[\leadsto \color{blue}{\left(x + \varepsilon\right) \cdot \left(x + \varepsilon\right)} - {x}^{2} \]
      2. unpow296.9%

        \[\leadsto \left(x + \varepsilon\right) \cdot \left(x + \varepsilon\right) - \color{blue}{x \cdot x} \]
      3. difference-of-squares96.9%

        \[\leadsto \color{blue}{\left(\left(x + \varepsilon\right) + x\right) \cdot \left(\left(x + \varepsilon\right) - x\right)} \]
      4. *-commutative96.9%

        \[\leadsto \color{blue}{\left(\left(x + \varepsilon\right) - x\right) \cdot \left(\left(x + \varepsilon\right) + x\right)} \]
      5. +-commutative96.9%

        \[\leadsto \left(\color{blue}{\left(\varepsilon + x\right)} - x\right) \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      6. associate--l+100.0%

        \[\leadsto \color{blue}{\left(\varepsilon + \left(x - x\right)\right)} \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      7. +-inverses100.0%

        \[\leadsto \left(\varepsilon + \color{blue}{0}\right) \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      8. +-rgt-identity100.0%

        \[\leadsto \color{blue}{\varepsilon} \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      9. +-commutative100.0%

        \[\leadsto \varepsilon \cdot \color{blue}{\left(x + \left(x + \varepsilon\right)\right)} \]
      10. associate-+r+100.0%

        \[\leadsto \varepsilon \cdot \color{blue}{\left(\left(x + x\right) + \varepsilon\right)} \]
      11. count-2100.0%

        \[\leadsto \varepsilon \cdot \left(\color{blue}{2 \cdot x} + \varepsilon\right) \]
      12. fma-def100.0%

        \[\leadsto \varepsilon \cdot \color{blue}{\mathsf{fma}\left(2, x, \varepsilon\right)} \]
    3. Simplified100.0%

      \[\leadsto \color{blue}{\varepsilon \cdot \mathsf{fma}\left(2, x, \varepsilon\right)} \]
    4. Taylor expanded in eps around inf 96.2%

      \[\leadsto \color{blue}{{\varepsilon}^{2}} \]
    5. Step-by-step derivation
      1. unpow296.2%

        \[\leadsto \color{blue}{\varepsilon \cdot \varepsilon} \]
    6. Simplified96.2%

      \[\leadsto \color{blue}{\varepsilon \cdot \varepsilon} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification92.1%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -3.8 \cdot 10^{-96} \lor \neg \left(x \leq 1.15 \cdot 10^{-99}\right):\\ \;\;\;\;2 \cdot \left(\varepsilon \cdot x\right)\\ \mathbf{else}:\\ \;\;\;\;\varepsilon \cdot \varepsilon\\ \end{array} \]

Alternative 3: 91.2% accurate, 22.7× speedup?

\[\begin{array}{l} \mathbf{if}\;x \leq -4 \cdot 10^{-96}:\\ \;\;\;\;2 \cdot \left(\varepsilon \cdot x\right)\\ \mathbf{elif}\;x \leq 1.8 \cdot 10^{-100}:\\ \;\;\;\;\varepsilon \cdot \varepsilon\\ \mathbf{else}:\\ \;\;\;\;\varepsilon \cdot \left(x + x\right)\\ \end{array} \]
Derivation
  1. Split input into 3 regimes
  2. if x < -3.9999999999999996e-96

    1. Initial program 29.8%

      \[{\left(x + \varepsilon\right)}^{2} - {x}^{2} \]
    2. Step-by-step derivation
      1. unpow229.8%

        \[\leadsto \color{blue}{\left(x + \varepsilon\right) \cdot \left(x + \varepsilon\right)} - {x}^{2} \]
      2. unpow229.8%

        \[\leadsto \left(x + \varepsilon\right) \cdot \left(x + \varepsilon\right) - \color{blue}{x \cdot x} \]
      3. difference-of-squares29.8%

        \[\leadsto \color{blue}{\left(\left(x + \varepsilon\right) + x\right) \cdot \left(\left(x + \varepsilon\right) - x\right)} \]
      4. *-commutative29.8%

        \[\leadsto \color{blue}{\left(\left(x + \varepsilon\right) - x\right) \cdot \left(\left(x + \varepsilon\right) + x\right)} \]
      5. +-commutative29.8%

        \[\leadsto \left(\color{blue}{\left(\varepsilon + x\right)} - x\right) \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      6. associate--l+100.0%

        \[\leadsto \color{blue}{\left(\varepsilon + \left(x - x\right)\right)} \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      7. +-inverses100.0%

        \[\leadsto \left(\varepsilon + \color{blue}{0}\right) \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      8. +-rgt-identity100.0%

        \[\leadsto \color{blue}{\varepsilon} \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      9. +-commutative100.0%

        \[\leadsto \varepsilon \cdot \color{blue}{\left(x + \left(x + \varepsilon\right)\right)} \]
      10. associate-+r+99.9%

        \[\leadsto \varepsilon \cdot \color{blue}{\left(\left(x + x\right) + \varepsilon\right)} \]
      11. count-299.9%

        \[\leadsto \varepsilon \cdot \left(\color{blue}{2 \cdot x} + \varepsilon\right) \]
      12. fma-def99.9%

        \[\leadsto \varepsilon \cdot \color{blue}{\mathsf{fma}\left(2, x, \varepsilon\right)} \]
    3. Simplified99.9%

      \[\leadsto \color{blue}{\varepsilon \cdot \mathsf{fma}\left(2, x, \varepsilon\right)} \]
    4. Taylor expanded in eps around 0 88.5%

      \[\leadsto \color{blue}{2 \cdot \left(\varepsilon \cdot x\right)} \]

    if -3.9999999999999996e-96 < x < 1.7999999999999999e-100

    1. Initial program 96.9%

      \[{\left(x + \varepsilon\right)}^{2} - {x}^{2} \]
    2. Step-by-step derivation
      1. unpow296.9%

        \[\leadsto \color{blue}{\left(x + \varepsilon\right) \cdot \left(x + \varepsilon\right)} - {x}^{2} \]
      2. unpow296.9%

        \[\leadsto \left(x + \varepsilon\right) \cdot \left(x + \varepsilon\right) - \color{blue}{x \cdot x} \]
      3. difference-of-squares96.9%

        \[\leadsto \color{blue}{\left(\left(x + \varepsilon\right) + x\right) \cdot \left(\left(x + \varepsilon\right) - x\right)} \]
      4. *-commutative96.9%

        \[\leadsto \color{blue}{\left(\left(x + \varepsilon\right) - x\right) \cdot \left(\left(x + \varepsilon\right) + x\right)} \]
      5. +-commutative96.9%

        \[\leadsto \left(\color{blue}{\left(\varepsilon + x\right)} - x\right) \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      6. associate--l+100.0%

        \[\leadsto \color{blue}{\left(\varepsilon + \left(x - x\right)\right)} \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      7. +-inverses100.0%

        \[\leadsto \left(\varepsilon + \color{blue}{0}\right) \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      8. +-rgt-identity100.0%

        \[\leadsto \color{blue}{\varepsilon} \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      9. +-commutative100.0%

        \[\leadsto \varepsilon \cdot \color{blue}{\left(x + \left(x + \varepsilon\right)\right)} \]
      10. associate-+r+100.0%

        \[\leadsto \varepsilon \cdot \color{blue}{\left(\left(x + x\right) + \varepsilon\right)} \]
      11. count-2100.0%

        \[\leadsto \varepsilon \cdot \left(\color{blue}{2 \cdot x} + \varepsilon\right) \]
      12. fma-def100.0%

        \[\leadsto \varepsilon \cdot \color{blue}{\mathsf{fma}\left(2, x, \varepsilon\right)} \]
    3. Simplified100.0%

      \[\leadsto \color{blue}{\varepsilon \cdot \mathsf{fma}\left(2, x, \varepsilon\right)} \]
    4. Taylor expanded in eps around inf 96.2%

      \[\leadsto \color{blue}{{\varepsilon}^{2}} \]
    5. Step-by-step derivation
      1. unpow296.2%

        \[\leadsto \color{blue}{\varepsilon \cdot \varepsilon} \]
    6. Simplified96.2%

      \[\leadsto \color{blue}{\varepsilon \cdot \varepsilon} \]

    if 1.7999999999999999e-100 < x

    1. Initial program 41.7%

      \[{\left(x + \varepsilon\right)}^{2} - {x}^{2} \]
    2. Step-by-step derivation
      1. unpow241.7%

        \[\leadsto \color{blue}{\left(x + \varepsilon\right) \cdot \left(x + \varepsilon\right)} - {x}^{2} \]
      2. unpow241.7%

        \[\leadsto \left(x + \varepsilon\right) \cdot \left(x + \varepsilon\right) - \color{blue}{x \cdot x} \]
      3. difference-of-squares41.7%

        \[\leadsto \color{blue}{\left(\left(x + \varepsilon\right) + x\right) \cdot \left(\left(x + \varepsilon\right) - x\right)} \]
      4. *-commutative41.7%

        \[\leadsto \color{blue}{\left(\left(x + \varepsilon\right) - x\right) \cdot \left(\left(x + \varepsilon\right) + x\right)} \]
      5. +-commutative41.7%

        \[\leadsto \left(\color{blue}{\left(\varepsilon + x\right)} - x\right) \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      6. associate--l+99.9%

        \[\leadsto \color{blue}{\left(\varepsilon + \left(x - x\right)\right)} \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      7. +-inverses99.9%

        \[\leadsto \left(\varepsilon + \color{blue}{0}\right) \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      8. +-rgt-identity99.9%

        \[\leadsto \color{blue}{\varepsilon} \cdot \left(\left(x + \varepsilon\right) + x\right) \]
      9. +-commutative99.9%

        \[\leadsto \varepsilon \cdot \color{blue}{\left(x + \left(x + \varepsilon\right)\right)} \]
      10. associate-+r+99.9%

        \[\leadsto \varepsilon \cdot \color{blue}{\left(\left(x + x\right) + \varepsilon\right)} \]
      11. count-299.9%

        \[\leadsto \varepsilon \cdot \left(\color{blue}{2 \cdot x} + \varepsilon\right) \]
      12. fma-def99.9%

        \[\leadsto \varepsilon \cdot \color{blue}{\mathsf{fma}\left(2, x, \varepsilon\right)} \]
    3. Simplified99.9%

      \[\leadsto \color{blue}{\varepsilon \cdot \mathsf{fma}\left(2, x, \varepsilon\right)} \]
    4. Step-by-step derivation
      1. fma-udef99.9%

        \[\leadsto \varepsilon \cdot \color{blue}{\left(2 \cdot x + \varepsilon\right)} \]
      2. distribute-rgt-in99.9%

        \[\leadsto \color{blue}{\left(2 \cdot x\right) \cdot \varepsilon + \varepsilon \cdot \varepsilon} \]
    5. Applied egg-rr99.9%

      \[\leadsto \color{blue}{\left(2 \cdot x\right) \cdot \varepsilon + \varepsilon \cdot \varepsilon} \]
    6. Taylor expanded in x around inf 84.3%

      \[\leadsto \color{blue}{2 \cdot \left(\varepsilon \cdot x\right)} \]
    7. Step-by-step derivation
      1. associate-*r*84.5%

        \[\leadsto \color{blue}{\left(2 \cdot \varepsilon\right) \cdot x} \]
      2. *-commutative84.5%

        \[\leadsto \color{blue}{\left(\varepsilon \cdot 2\right)} \cdot x \]
      3. associate-*r*84.5%

        \[\leadsto \color{blue}{\varepsilon \cdot \left(2 \cdot x\right)} \]
      4. count-284.5%

        \[\leadsto \varepsilon \cdot \color{blue}{\left(x + x\right)} \]
    8. Simplified84.5%

      \[\leadsto \color{blue}{\varepsilon \cdot \left(x + x\right)} \]
  3. Recombined 3 regimes into one program.
  4. Final simplification92.1%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -4 \cdot 10^{-96}:\\ \;\;\;\;2 \cdot \left(\varepsilon \cdot x\right)\\ \mathbf{elif}\;x \leq 1.8 \cdot 10^{-100}:\\ \;\;\;\;\varepsilon \cdot \varepsilon\\ \mathbf{else}:\\ \;\;\;\;\varepsilon \cdot \left(x + x\right)\\ \end{array} \]

Alternative 4: 100.0% accurate, 29.6× speedup?

\[\varepsilon \cdot \left(\varepsilon + \left(x + x\right)\right) \]
Derivation
  1. Initial program 71.1%

    \[{\left(x + \varepsilon\right)}^{2} - {x}^{2} \]
  2. Step-by-step derivation
    1. unpow271.1%

      \[\leadsto {\left(x + \varepsilon\right)}^{2} - \color{blue}{x \cdot x} \]
  3. Simplified71.1%

    \[\leadsto \color{blue}{{\left(x + \varepsilon\right)}^{2} - x \cdot x} \]
  4. Step-by-step derivation
    1. unpow271.1%

      \[\leadsto \color{blue}{\left(x + \varepsilon\right) \cdot \left(x + \varepsilon\right)} - x \cdot x \]
    2. +-commutative71.1%

      \[\leadsto \left(x + \varepsilon\right) \cdot \color{blue}{\left(\varepsilon + x\right)} - x \cdot x \]
    3. +-commutative71.1%

      \[\leadsto \color{blue}{\left(\varepsilon + x\right)} \cdot \left(\varepsilon + x\right) - x \cdot x \]
  5. Applied egg-rr71.1%

    \[\leadsto \color{blue}{\left(\varepsilon + x\right) \cdot \left(\varepsilon + x\right)} - x \cdot x \]
  6. Step-by-step derivation
    1. distribute-rgt-in71.2%

      \[\leadsto \color{blue}{\left(\varepsilon \cdot \left(\varepsilon + x\right) + x \cdot \left(\varepsilon + x\right)\right)} - x \cdot x \]
    2. *-commutative71.2%

      \[\leadsto \left(\color{blue}{\left(\varepsilon + x\right) \cdot \varepsilon} + x \cdot \left(\varepsilon + x\right)\right) - x \cdot x \]
    3. associate--l+74.6%

      \[\leadsto \color{blue}{\left(\varepsilon + x\right) \cdot \varepsilon + \left(x \cdot \left(\varepsilon + x\right) - x \cdot x\right)} \]
    4. +-commutative74.6%

      \[\leadsto \color{blue}{\left(x \cdot \left(\varepsilon + x\right) - x \cdot x\right) + \left(\varepsilon + x\right) \cdot \varepsilon} \]
    5. distribute-lft-out--74.6%

      \[\leadsto \color{blue}{x \cdot \left(\left(\varepsilon + x\right) - x\right)} + \left(\varepsilon + x\right) \cdot \varepsilon \]
    6. +-commutative74.6%

      \[\leadsto x \cdot \left(\color{blue}{\left(x + \varepsilon\right)} - x\right) + \left(\varepsilon + x\right) \cdot \varepsilon \]
    7. *-commutative74.6%

      \[\leadsto x \cdot \left(\left(x + \varepsilon\right) - x\right) + \color{blue}{\varepsilon \cdot \left(\varepsilon + x\right)} \]
    8. +-commutative74.6%

      \[\leadsto x \cdot \left(\left(x + \varepsilon\right) - x\right) + \varepsilon \cdot \color{blue}{\left(x + \varepsilon\right)} \]
  7. Applied egg-rr74.6%

    \[\leadsto \color{blue}{x \cdot \left(\left(x + \varepsilon\right) - x\right) + \varepsilon \cdot \left(x + \varepsilon\right)} \]
  8. Taylor expanded in x around 0 99.9%

    \[\leadsto x \cdot \color{blue}{\varepsilon} + \varepsilon \cdot \left(x + \varepsilon\right) \]
  9. Taylor expanded in x around 0 99.9%

    \[\leadsto \color{blue}{{\varepsilon}^{2} + 2 \cdot \left(\varepsilon \cdot x\right)} \]
  10. Step-by-step derivation
    1. unpow299.9%

      \[\leadsto \color{blue}{\varepsilon \cdot \varepsilon} + 2 \cdot \left(\varepsilon \cdot x\right) \]
    2. *-commutative99.9%

      \[\leadsto \varepsilon \cdot \varepsilon + 2 \cdot \color{blue}{\left(x \cdot \varepsilon\right)} \]
    3. associate-*r*100.0%

      \[\leadsto \varepsilon \cdot \varepsilon + \color{blue}{\left(2 \cdot x\right) \cdot \varepsilon} \]
    4. count-2100.0%

      \[\leadsto \varepsilon \cdot \varepsilon + \color{blue}{\left(x + x\right)} \cdot \varepsilon \]
    5. distribute-rgt-in100.0%

      \[\leadsto \color{blue}{\varepsilon \cdot \left(\varepsilon + \left(x + x\right)\right)} \]
  11. Simplified100.0%

    \[\leadsto \color{blue}{\varepsilon \cdot \left(\varepsilon + \left(x + x\right)\right)} \]
  12. Final simplification100.0%

    \[\leadsto \varepsilon \cdot \left(\varepsilon + \left(x + x\right)\right) \]

Alternative 5: 72.1% accurate, 69.0× speedup?

\[\varepsilon \cdot \varepsilon \]
Derivation
  1. Initial program 71.1%

    \[{\left(x + \varepsilon\right)}^{2} - {x}^{2} \]
  2. Step-by-step derivation
    1. unpow271.1%

      \[\leadsto \color{blue}{\left(x + \varepsilon\right) \cdot \left(x + \varepsilon\right)} - {x}^{2} \]
    2. unpow271.1%

      \[\leadsto \left(x + \varepsilon\right) \cdot \left(x + \varepsilon\right) - \color{blue}{x \cdot x} \]
    3. difference-of-squares71.1%

      \[\leadsto \color{blue}{\left(\left(x + \varepsilon\right) + x\right) \cdot \left(\left(x + \varepsilon\right) - x\right)} \]
    4. *-commutative71.1%

      \[\leadsto \color{blue}{\left(\left(x + \varepsilon\right) - x\right) \cdot \left(\left(x + \varepsilon\right) + x\right)} \]
    5. +-commutative71.1%

      \[\leadsto \left(\color{blue}{\left(\varepsilon + x\right)} - x\right) \cdot \left(\left(x + \varepsilon\right) + x\right) \]
    6. associate--l+100.0%

      \[\leadsto \color{blue}{\left(\varepsilon + \left(x - x\right)\right)} \cdot \left(\left(x + \varepsilon\right) + x\right) \]
    7. +-inverses100.0%

      \[\leadsto \left(\varepsilon + \color{blue}{0}\right) \cdot \left(\left(x + \varepsilon\right) + x\right) \]
    8. +-rgt-identity100.0%

      \[\leadsto \color{blue}{\varepsilon} \cdot \left(\left(x + \varepsilon\right) + x\right) \]
    9. +-commutative100.0%

      \[\leadsto \varepsilon \cdot \color{blue}{\left(x + \left(x + \varepsilon\right)\right)} \]
    10. associate-+r+100.0%

      \[\leadsto \varepsilon \cdot \color{blue}{\left(\left(x + x\right) + \varepsilon\right)} \]
    11. count-2100.0%

      \[\leadsto \varepsilon \cdot \left(\color{blue}{2 \cdot x} + \varepsilon\right) \]
    12. fma-def100.0%

      \[\leadsto \varepsilon \cdot \color{blue}{\mathsf{fma}\left(2, x, \varepsilon\right)} \]
  3. Simplified100.0%

    \[\leadsto \color{blue}{\varepsilon \cdot \mathsf{fma}\left(2, x, \varepsilon\right)} \]
  4. Taylor expanded in eps around inf 68.7%

    \[\leadsto \color{blue}{{\varepsilon}^{2}} \]
  5. Step-by-step derivation
    1. unpow268.7%

      \[\leadsto \color{blue}{\varepsilon \cdot \varepsilon} \]
  6. Simplified68.7%

    \[\leadsto \color{blue}{\varepsilon \cdot \varepsilon} \]
  7. Final simplification68.7%

    \[\leadsto \varepsilon \cdot \varepsilon \]

Reproduce

?
herbie shell --seed 2023167 
(FPCore (x eps)
  :name "ENA, Section 1.4, Exercise 4b, n=2"
  :precision binary64
  :pre (and (and (<= -1000000000.0 x) (<= x 1000000000.0)) (and (<= -1.0 eps) (<= eps 1.0)))
  (- (pow (+ x eps) 2.0) (pow x 2.0)))