sintan (problem 3.4.5)

Percentage Accurate: 1.8% → 99.9%
Time: 17.1s
Alternatives: 4
Speedup: 218.0×

Specification

?
\[-0.4 \leq \varepsilon \land \varepsilon \leq 0.4\]
\[\begin{array}{l} \\ \frac{\varepsilon - \sin \varepsilon}{\varepsilon - \tan \varepsilon} \end{array} \]
(FPCore (eps) :precision binary64 (/ (- eps (sin eps)) (- eps (tan eps))))
double code(double eps) {
	return (eps - sin(eps)) / (eps - tan(eps));
}
real(8) function code(eps)
    real(8), intent (in) :: eps
    code = (eps - sin(eps)) / (eps - tan(eps))
end function
public static double code(double eps) {
	return (eps - Math.sin(eps)) / (eps - Math.tan(eps));
}
def code(eps):
	return (eps - math.sin(eps)) / (eps - math.tan(eps))
function code(eps)
	return Float64(Float64(eps - sin(eps)) / Float64(eps - tan(eps)))
end
function tmp = code(eps)
	tmp = (eps - sin(eps)) / (eps - tan(eps));
end
code[eps_] := N[(N[(eps - N[Sin[eps], $MachinePrecision]), $MachinePrecision] / N[(eps - N[Tan[eps], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\varepsilon - \sin \varepsilon}{\varepsilon - \tan \varepsilon}
\end{array}

Sampling outcomes in binary64 precision:

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 4 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.

Initial Program: 1.8% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{\varepsilon - \sin \varepsilon}{\varepsilon - \tan \varepsilon} \end{array} \]
(FPCore (eps) :precision binary64 (/ (- eps (sin eps)) (- eps (tan eps))))
double code(double eps) {
	return (eps - sin(eps)) / (eps - tan(eps));
}
real(8) function code(eps)
    real(8), intent (in) :: eps
    code = (eps - sin(eps)) / (eps - tan(eps))
end function
public static double code(double eps) {
	return (eps - Math.sin(eps)) / (eps - Math.tan(eps));
}
def code(eps):
	return (eps - math.sin(eps)) / (eps - math.tan(eps))
function code(eps)
	return Float64(Float64(eps - sin(eps)) / Float64(eps - tan(eps)))
end
function tmp = code(eps)
	tmp = (eps - sin(eps)) / (eps - tan(eps));
end
code[eps_] := N[(N[(eps - N[Sin[eps], $MachinePrecision]), $MachinePrecision] / N[(eps - N[Tan[eps], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\varepsilon - \sin \varepsilon}{\varepsilon - \tan \varepsilon}
\end{array}

Alternative 1: 99.9% accurate, 5.7× speedup?

\[\begin{array}{l} \\ \left(\varepsilon \cdot \varepsilon\right) \cdot \mathsf{fma}\left(\left(0.00024107142857142857 \cdot \left(\varepsilon \cdot \varepsilon\right) - 0.009642857142857142\right) \cdot \varepsilon, \varepsilon, 0.225\right) - 0.5 \end{array} \]
(FPCore (eps)
 :precision binary64
 (-
  (*
   (* eps eps)
   (fma
    (* (- (* 0.00024107142857142857 (* eps eps)) 0.009642857142857142) eps)
    eps
    0.225))
  0.5))
double code(double eps) {
	return ((eps * eps) * fma((((0.00024107142857142857 * (eps * eps)) - 0.009642857142857142) * eps), eps, 0.225)) - 0.5;
}
function code(eps)
	return Float64(Float64(Float64(eps * eps) * fma(Float64(Float64(Float64(0.00024107142857142857 * Float64(eps * eps)) - 0.009642857142857142) * eps), eps, 0.225)) - 0.5)
end
code[eps_] := N[(N[(N[(eps * eps), $MachinePrecision] * N[(N[(N[(N[(0.00024107142857142857 * N[(eps * eps), $MachinePrecision]), $MachinePrecision] - 0.009642857142857142), $MachinePrecision] * eps), $MachinePrecision] * eps + 0.225), $MachinePrecision]), $MachinePrecision] - 0.5), $MachinePrecision]
\begin{array}{l}

\\
\left(\varepsilon \cdot \varepsilon\right) \cdot \mathsf{fma}\left(\left(0.00024107142857142857 \cdot \left(\varepsilon \cdot \varepsilon\right) - 0.009642857142857142\right) \cdot \varepsilon, \varepsilon, 0.225\right) - 0.5
\end{array}
Derivation
  1. Initial program 2.1%

    \[\frac{\varepsilon - \sin \varepsilon}{\varepsilon - \tan \varepsilon} \]
  2. Add Preprocessing
  3. Taylor expanded in eps around 0

    \[\leadsto \color{blue}{{\varepsilon}^{2} \cdot \left(\frac{9}{40} + {\varepsilon}^{2} \cdot \left(\frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}\right)\right) - \frac{1}{2}} \]
  4. Step-by-step derivation
    1. +-commutativeN/A

      \[\leadsto {\varepsilon}^{2} \cdot \color{blue}{\left({\varepsilon}^{2} \cdot \left(\frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}\right) + \frac{9}{40}\right)} - \frac{1}{2} \]
    2. distribute-lft-inN/A

      \[\leadsto \color{blue}{\left({\varepsilon}^{2} \cdot \left({\varepsilon}^{2} \cdot \left(\frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}\right)\right) + {\varepsilon}^{2} \cdot \frac{9}{40}\right)} - \frac{1}{2} \]
    3. *-commutativeN/A

      \[\leadsto \left({\varepsilon}^{2} \cdot \left({\varepsilon}^{2} \cdot \left(\frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}\right)\right) + \color{blue}{\frac{9}{40} \cdot {\varepsilon}^{2}}\right) - \frac{1}{2} \]
    4. associate--l+N/A

      \[\leadsto \color{blue}{{\varepsilon}^{2} \cdot \left({\varepsilon}^{2} \cdot \left(\frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}\right)\right) + \left(\frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right)} \]
    5. associate-*r*N/A

      \[\leadsto \color{blue}{\left({\varepsilon}^{2} \cdot {\varepsilon}^{2}\right) \cdot \left(\frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}\right)} + \left(\frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
    6. lower-fma.f64N/A

      \[\leadsto \color{blue}{\mathsf{fma}\left({\varepsilon}^{2} \cdot {\varepsilon}^{2}, \frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right)} \]
    7. pow-sqrN/A

      \[\leadsto \mathsf{fma}\left(\color{blue}{{\varepsilon}^{\left(2 \cdot 2\right)}}, \frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
    8. lower-pow.f64N/A

      \[\leadsto \mathsf{fma}\left(\color{blue}{{\varepsilon}^{\left(2 \cdot 2\right)}}, \frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
    9. metadata-evalN/A

      \[\leadsto \mathsf{fma}\left({\varepsilon}^{\color{blue}{4}}, \frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
    10. lower--.f64N/A

      \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \color{blue}{\frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
    11. lower-*.f64N/A

      \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \color{blue}{\frac{27}{112000} \cdot {\varepsilon}^{2}} - \frac{27}{2800}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
    12. unpow2N/A

      \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \frac{27}{112000} \cdot \color{blue}{\left(\varepsilon \cdot \varepsilon\right)} - \frac{27}{2800}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
    13. lower-*.f64N/A

      \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \frac{27}{112000} \cdot \color{blue}{\left(\varepsilon \cdot \varepsilon\right)} - \frac{27}{2800}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
    14. lower--.f64N/A

      \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \frac{27}{112000} \cdot \left(\varepsilon \cdot \varepsilon\right) - \frac{27}{2800}, \color{blue}{\frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}}\right) \]
    15. *-commutativeN/A

      \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \frac{27}{112000} \cdot \left(\varepsilon \cdot \varepsilon\right) - \frac{27}{2800}, \color{blue}{{\varepsilon}^{2} \cdot \frac{9}{40}} - \frac{1}{2}\right) \]
    16. lower-*.f64N/A

      \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \frac{27}{112000} \cdot \left(\varepsilon \cdot \varepsilon\right) - \frac{27}{2800}, \color{blue}{{\varepsilon}^{2} \cdot \frac{9}{40}} - \frac{1}{2}\right) \]
    17. unpow2N/A

      \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \frac{27}{112000} \cdot \left(\varepsilon \cdot \varepsilon\right) - \frac{27}{2800}, \color{blue}{\left(\varepsilon \cdot \varepsilon\right)} \cdot \frac{9}{40} - \frac{1}{2}\right) \]
    18. lower-*.f6499.9

      \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, 0.00024107142857142857 \cdot \left(\varepsilon \cdot \varepsilon\right) - 0.009642857142857142, \color{blue}{\left(\varepsilon \cdot \varepsilon\right)} \cdot 0.225 - 0.5\right) \]
  5. Applied rewrites99.9%

    \[\leadsto \color{blue}{\mathsf{fma}\left({\varepsilon}^{4}, 0.00024107142857142857 \cdot \left(\varepsilon \cdot \varepsilon\right) - 0.009642857142857142, \left(\varepsilon \cdot \varepsilon\right) \cdot 0.225 - 0.5\right)} \]
  6. Step-by-step derivation
    1. Applied rewrites99.9%

      \[\leadsto \mathsf{fma}\left(\left(\left(\varepsilon \cdot \varepsilon\right) \cdot 0.00024107142857142857 - 0.009642857142857142\right) \cdot \left(\varepsilon \cdot \varepsilon\right), \color{blue}{\varepsilon \cdot \varepsilon}, 0.225 \cdot \left(\varepsilon \cdot \varepsilon\right) - 0.5\right) \]
    2. Step-by-step derivation
      1. Applied rewrites99.9%

        \[\leadsto \left(\varepsilon \cdot \varepsilon\right) \cdot \mathsf{fma}\left(\left(0.00024107142857142857 \cdot \left(\varepsilon \cdot \varepsilon\right) - 0.009642857142857142\right) \cdot \varepsilon, \varepsilon, 0.225\right) - \color{blue}{0.5} \]
      2. Add Preprocessing

      Alternative 2: 99.8% accurate, 8.7× speedup?

      \[\begin{array}{l} \\ \left(\mathsf{fma}\left(-0.009642857142857142, \varepsilon \cdot \varepsilon, 0.225\right) \cdot \varepsilon\right) \cdot \varepsilon - 0.5 \end{array} \]
      (FPCore (eps)
       :precision binary64
       (- (* (* (fma -0.009642857142857142 (* eps eps) 0.225) eps) eps) 0.5))
      double code(double eps) {
      	return ((fma(-0.009642857142857142, (eps * eps), 0.225) * eps) * eps) - 0.5;
      }
      
      function code(eps)
      	return Float64(Float64(Float64(fma(-0.009642857142857142, Float64(eps * eps), 0.225) * eps) * eps) - 0.5)
      end
      
      code[eps_] := N[(N[(N[(N[(-0.009642857142857142 * N[(eps * eps), $MachinePrecision] + 0.225), $MachinePrecision] * eps), $MachinePrecision] * eps), $MachinePrecision] - 0.5), $MachinePrecision]
      
      \begin{array}{l}
      
      \\
      \left(\mathsf{fma}\left(-0.009642857142857142, \varepsilon \cdot \varepsilon, 0.225\right) \cdot \varepsilon\right) \cdot \varepsilon - 0.5
      \end{array}
      
      Derivation
      1. Initial program 2.1%

        \[\frac{\varepsilon - \sin \varepsilon}{\varepsilon - \tan \varepsilon} \]
      2. Add Preprocessing
      3. Taylor expanded in eps around 0

        \[\leadsto \color{blue}{{\varepsilon}^{2} \cdot \left(\frac{9}{40} + {\varepsilon}^{2} \cdot \left(\frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}\right)\right) - \frac{1}{2}} \]
      4. Step-by-step derivation
        1. +-commutativeN/A

          \[\leadsto {\varepsilon}^{2} \cdot \color{blue}{\left({\varepsilon}^{2} \cdot \left(\frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}\right) + \frac{9}{40}\right)} - \frac{1}{2} \]
        2. distribute-lft-inN/A

          \[\leadsto \color{blue}{\left({\varepsilon}^{2} \cdot \left({\varepsilon}^{2} \cdot \left(\frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}\right)\right) + {\varepsilon}^{2} \cdot \frac{9}{40}\right)} - \frac{1}{2} \]
        3. *-commutativeN/A

          \[\leadsto \left({\varepsilon}^{2} \cdot \left({\varepsilon}^{2} \cdot \left(\frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}\right)\right) + \color{blue}{\frac{9}{40} \cdot {\varepsilon}^{2}}\right) - \frac{1}{2} \]
        4. associate--l+N/A

          \[\leadsto \color{blue}{{\varepsilon}^{2} \cdot \left({\varepsilon}^{2} \cdot \left(\frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}\right)\right) + \left(\frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right)} \]
        5. associate-*r*N/A

          \[\leadsto \color{blue}{\left({\varepsilon}^{2} \cdot {\varepsilon}^{2}\right) \cdot \left(\frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}\right)} + \left(\frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
        6. lower-fma.f64N/A

          \[\leadsto \color{blue}{\mathsf{fma}\left({\varepsilon}^{2} \cdot {\varepsilon}^{2}, \frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right)} \]
        7. pow-sqrN/A

          \[\leadsto \mathsf{fma}\left(\color{blue}{{\varepsilon}^{\left(2 \cdot 2\right)}}, \frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
        8. lower-pow.f64N/A

          \[\leadsto \mathsf{fma}\left(\color{blue}{{\varepsilon}^{\left(2 \cdot 2\right)}}, \frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
        9. metadata-evalN/A

          \[\leadsto \mathsf{fma}\left({\varepsilon}^{\color{blue}{4}}, \frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
        10. lower--.f64N/A

          \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \color{blue}{\frac{27}{112000} \cdot {\varepsilon}^{2} - \frac{27}{2800}}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
        11. lower-*.f64N/A

          \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \color{blue}{\frac{27}{112000} \cdot {\varepsilon}^{2}} - \frac{27}{2800}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
        12. unpow2N/A

          \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \frac{27}{112000} \cdot \color{blue}{\left(\varepsilon \cdot \varepsilon\right)} - \frac{27}{2800}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
        13. lower-*.f64N/A

          \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \frac{27}{112000} \cdot \color{blue}{\left(\varepsilon \cdot \varepsilon\right)} - \frac{27}{2800}, \frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}\right) \]
        14. lower--.f64N/A

          \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \frac{27}{112000} \cdot \left(\varepsilon \cdot \varepsilon\right) - \frac{27}{2800}, \color{blue}{\frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}}\right) \]
        15. *-commutativeN/A

          \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \frac{27}{112000} \cdot \left(\varepsilon \cdot \varepsilon\right) - \frac{27}{2800}, \color{blue}{{\varepsilon}^{2} \cdot \frac{9}{40}} - \frac{1}{2}\right) \]
        16. lower-*.f64N/A

          \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \frac{27}{112000} \cdot \left(\varepsilon \cdot \varepsilon\right) - \frac{27}{2800}, \color{blue}{{\varepsilon}^{2} \cdot \frac{9}{40}} - \frac{1}{2}\right) \]
        17. unpow2N/A

          \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, \frac{27}{112000} \cdot \left(\varepsilon \cdot \varepsilon\right) - \frac{27}{2800}, \color{blue}{\left(\varepsilon \cdot \varepsilon\right)} \cdot \frac{9}{40} - \frac{1}{2}\right) \]
        18. lower-*.f6499.9

          \[\leadsto \mathsf{fma}\left({\varepsilon}^{4}, 0.00024107142857142857 \cdot \left(\varepsilon \cdot \varepsilon\right) - 0.009642857142857142, \color{blue}{\left(\varepsilon \cdot \varepsilon\right)} \cdot 0.225 - 0.5\right) \]
      5. Applied rewrites99.9%

        \[\leadsto \color{blue}{\mathsf{fma}\left({\varepsilon}^{4}, 0.00024107142857142857 \cdot \left(\varepsilon \cdot \varepsilon\right) - 0.009642857142857142, \left(\varepsilon \cdot \varepsilon\right) \cdot 0.225 - 0.5\right)} \]
      6. Step-by-step derivation
        1. Applied rewrites99.9%

          \[\leadsto \mathsf{fma}\left(\left(\left(\varepsilon \cdot \varepsilon\right) \cdot 0.00024107142857142857 - 0.009642857142857142\right) \cdot \left(\varepsilon \cdot \varepsilon\right), \color{blue}{\varepsilon \cdot \varepsilon}, 0.225 \cdot \left(\varepsilon \cdot \varepsilon\right) - 0.5\right) \]
        2. Taylor expanded in eps around 0

          \[\leadsto {\varepsilon}^{2} \cdot \left(\frac{9}{40} + \frac{-27}{2800} \cdot {\varepsilon}^{2}\right) - \color{blue}{\frac{1}{2}} \]
        3. Step-by-step derivation
          1. Applied rewrites99.8%

            \[\leadsto \left(\mathsf{fma}\left(-0.009642857142857142, \varepsilon \cdot \varepsilon, 0.225\right) \cdot \varepsilon\right) \cdot \varepsilon - \color{blue}{0.5} \]
          2. Add Preprocessing

          Alternative 3: 99.6% accurate, 15.6× speedup?

          \[\begin{array}{l} \\ \left(\varepsilon \cdot \varepsilon\right) \cdot 0.225 - 0.5 \end{array} \]
          (FPCore (eps) :precision binary64 (- (* (* eps eps) 0.225) 0.5))
          double code(double eps) {
          	return ((eps * eps) * 0.225) - 0.5;
          }
          
          real(8) function code(eps)
              real(8), intent (in) :: eps
              code = ((eps * eps) * 0.225d0) - 0.5d0
          end function
          
          public static double code(double eps) {
          	return ((eps * eps) * 0.225) - 0.5;
          }
          
          def code(eps):
          	return ((eps * eps) * 0.225) - 0.5
          
          function code(eps)
          	return Float64(Float64(Float64(eps * eps) * 0.225) - 0.5)
          end
          
          function tmp = code(eps)
          	tmp = ((eps * eps) * 0.225) - 0.5;
          end
          
          code[eps_] := N[(N[(N[(eps * eps), $MachinePrecision] * 0.225), $MachinePrecision] - 0.5), $MachinePrecision]
          
          \begin{array}{l}
          
          \\
          \left(\varepsilon \cdot \varepsilon\right) \cdot 0.225 - 0.5
          \end{array}
          
          Derivation
          1. Initial program 2.1%

            \[\frac{\varepsilon - \sin \varepsilon}{\varepsilon - \tan \varepsilon} \]
          2. Add Preprocessing
          3. Taylor expanded in eps around 0

            \[\leadsto \color{blue}{\frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}} \]
          4. Step-by-step derivation
            1. lower--.f64N/A

              \[\leadsto \color{blue}{\frac{9}{40} \cdot {\varepsilon}^{2} - \frac{1}{2}} \]
            2. *-commutativeN/A

              \[\leadsto \color{blue}{{\varepsilon}^{2} \cdot \frac{9}{40}} - \frac{1}{2} \]
            3. lower-*.f64N/A

              \[\leadsto \color{blue}{{\varepsilon}^{2} \cdot \frac{9}{40}} - \frac{1}{2} \]
            4. unpow2N/A

              \[\leadsto \color{blue}{\left(\varepsilon \cdot \varepsilon\right)} \cdot \frac{9}{40} - \frac{1}{2} \]
            5. lower-*.f6499.5

              \[\leadsto \color{blue}{\left(\varepsilon \cdot \varepsilon\right)} \cdot 0.225 - 0.5 \]
          5. Applied rewrites99.5%

            \[\leadsto \color{blue}{\left(\varepsilon \cdot \varepsilon\right) \cdot 0.225 - 0.5} \]
          6. Add Preprocessing

          Alternative 4: 99.0% accurate, 218.0× speedup?

          \[\begin{array}{l} \\ -0.5 \end{array} \]
          (FPCore (eps) :precision binary64 -0.5)
          double code(double eps) {
          	return -0.5;
          }
          
          real(8) function code(eps)
              real(8), intent (in) :: eps
              code = -0.5d0
          end function
          
          public static double code(double eps) {
          	return -0.5;
          }
          
          def code(eps):
          	return -0.5
          
          function code(eps)
          	return -0.5
          end
          
          function tmp = code(eps)
          	tmp = -0.5;
          end
          
          code[eps_] := -0.5
          
          \begin{array}{l}
          
          \\
          -0.5
          \end{array}
          
          Derivation
          1. Initial program 2.1%

            \[\frac{\varepsilon - \sin \varepsilon}{\varepsilon - \tan \varepsilon} \]
          2. Add Preprocessing
          3. Taylor expanded in eps around 0

            \[\leadsto \color{blue}{\frac{-1}{2}} \]
          4. Step-by-step derivation
            1. Applied rewrites98.9%

              \[\leadsto \color{blue}{-0.5} \]
            2. Add Preprocessing

            Developer Target 1: 99.6% accurate, 15.6× speedup?

            \[\begin{array}{l} \\ \left(0.225 \cdot \varepsilon\right) \cdot \varepsilon - 0.5 \end{array} \]
            (FPCore (eps) :precision binary64 (- (* (* 0.225 eps) eps) 0.5))
            double code(double eps) {
            	return ((0.225 * eps) * eps) - 0.5;
            }
            
            real(8) function code(eps)
                real(8), intent (in) :: eps
                code = ((0.225d0 * eps) * eps) - 0.5d0
            end function
            
            public static double code(double eps) {
            	return ((0.225 * eps) * eps) - 0.5;
            }
            
            def code(eps):
            	return ((0.225 * eps) * eps) - 0.5
            
            function code(eps)
            	return Float64(Float64(Float64(0.225 * eps) * eps) - 0.5)
            end
            
            function tmp = code(eps)
            	tmp = ((0.225 * eps) * eps) - 0.5;
            end
            
            code[eps_] := N[(N[(N[(0.225 * eps), $MachinePrecision] * eps), $MachinePrecision] - 0.5), $MachinePrecision]
            
            \begin{array}{l}
            
            \\
            \left(0.225 \cdot \varepsilon\right) \cdot \varepsilon - 0.5
            \end{array}
            

            Reproduce

            ?
            herbie shell --seed 2024340 
            (FPCore (eps)
              :name "sintan (problem 3.4.5)"
              :precision binary64
              :pre (and (<= -0.4 eps) (<= eps 0.4))
            
              :alt
              (! :herbie-platform default (- (* 9/40 eps eps) 1/2))
            
              (/ (- eps (sin eps)) (- eps (tan eps))))