Falkner and Boettcher, Appendix B, 2

Percentage Accurate: 100.0% → 100.0%
Time: 10.2s
Alternatives: 4
Speedup: 1.7×

Specification

?
\[\begin{array}{l} \\ \left(\frac{\sqrt{2}}{4} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \end{array} \]
(FPCore (v)
 :precision binary64
 (* (* (/ (sqrt 2.0) 4.0) (sqrt (- 1.0 (* 3.0 (* v v))))) (- 1.0 (* v v))))
double code(double v) {
	return ((sqrt(2.0) / 4.0) * sqrt((1.0 - (3.0 * (v * v))))) * (1.0 - (v * v));
}
real(8) function code(v)
    real(8), intent (in) :: v
    code = ((sqrt(2.0d0) / 4.0d0) * sqrt((1.0d0 - (3.0d0 * (v * v))))) * (1.0d0 - (v * v))
end function
public static double code(double v) {
	return ((Math.sqrt(2.0) / 4.0) * Math.sqrt((1.0 - (3.0 * (v * v))))) * (1.0 - (v * v));
}
def code(v):
	return ((math.sqrt(2.0) / 4.0) * math.sqrt((1.0 - (3.0 * (v * v))))) * (1.0 - (v * v))
function code(v)
	return Float64(Float64(Float64(sqrt(2.0) / 4.0) * sqrt(Float64(1.0 - Float64(3.0 * Float64(v * v))))) * Float64(1.0 - Float64(v * v)))
end
function tmp = code(v)
	tmp = ((sqrt(2.0) / 4.0) * sqrt((1.0 - (3.0 * (v * v))))) * (1.0 - (v * v));
end
code[v_] := N[(N[(N[(N[Sqrt[2.0], $MachinePrecision] / 4.0), $MachinePrecision] * N[Sqrt[N[(1.0 - N[(3.0 * N[(v * v), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * N[(1.0 - N[(v * v), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\left(\frac{\sqrt{2}}{4} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right)
\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: 100.0% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \left(\frac{\sqrt{2}}{4} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \end{array} \]
(FPCore (v)
 :precision binary64
 (* (* (/ (sqrt 2.0) 4.0) (sqrt (- 1.0 (* 3.0 (* v v))))) (- 1.0 (* v v))))
double code(double v) {
	return ((sqrt(2.0) / 4.0) * sqrt((1.0 - (3.0 * (v * v))))) * (1.0 - (v * v));
}
real(8) function code(v)
    real(8), intent (in) :: v
    code = ((sqrt(2.0d0) / 4.0d0) * sqrt((1.0d0 - (3.0d0 * (v * v))))) * (1.0d0 - (v * v))
end function
public static double code(double v) {
	return ((Math.sqrt(2.0) / 4.0) * Math.sqrt((1.0 - (3.0 * (v * v))))) * (1.0 - (v * v));
}
def code(v):
	return ((math.sqrt(2.0) / 4.0) * math.sqrt((1.0 - (3.0 * (v * v))))) * (1.0 - (v * v))
function code(v)
	return Float64(Float64(Float64(sqrt(2.0) / 4.0) * sqrt(Float64(1.0 - Float64(3.0 * Float64(v * v))))) * Float64(1.0 - Float64(v * v)))
end
function tmp = code(v)
	tmp = ((sqrt(2.0) / 4.0) * sqrt((1.0 - (3.0 * (v * v))))) * (1.0 - (v * v));
end
code[v_] := N[(N[(N[(N[Sqrt[2.0], $MachinePrecision] / 4.0), $MachinePrecision] * N[Sqrt[N[(1.0 - N[(3.0 * N[(v * v), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * N[(1.0 - N[(v * v), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\left(\frac{\sqrt{2}}{4} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right)
\end{array}

Alternative 1: 100.0% accurate, 1.1× speedup?

\[\begin{array}{l} \\ \frac{\sqrt{\mathsf{fma}\left(v, v \cdot -6, 2\right)} \cdot -0.25}{\frac{1}{\mathsf{fma}\left(v, v, -1\right)}} \end{array} \]
(FPCore (v)
 :precision binary64
 (/ (* (sqrt (fma v (* v -6.0) 2.0)) -0.25) (/ 1.0 (fma v v -1.0))))
double code(double v) {
	return (sqrt(fma(v, (v * -6.0), 2.0)) * -0.25) / (1.0 / fma(v, v, -1.0));
}
function code(v)
	return Float64(Float64(sqrt(fma(v, Float64(v * -6.0), 2.0)) * -0.25) / Float64(1.0 / fma(v, v, -1.0)))
end
code[v_] := N[(N[(N[Sqrt[N[(v * N[(v * -6.0), $MachinePrecision] + 2.0), $MachinePrecision]], $MachinePrecision] * -0.25), $MachinePrecision] / N[(1.0 / N[(v * v + -1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{\sqrt{\mathsf{fma}\left(v, v \cdot -6, 2\right)} \cdot -0.25}{\frac{1}{\mathsf{fma}\left(v, v, -1\right)}}
\end{array}
Derivation
  1. Initial program 100.0%

    \[\left(\frac{\sqrt{2}}{4} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. div-invN/A

      \[\leadsto \left(\color{blue}{\left(\sqrt{2} \cdot \frac{1}{4}\right)} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \]
    2. *-lowering-*.f64N/A

      \[\leadsto \left(\color{blue}{\left(\sqrt{2} \cdot \frac{1}{4}\right)} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \]
    3. sqrt-lowering-sqrt.f64N/A

      \[\leadsto \left(\left(\color{blue}{\sqrt{2}} \cdot \frac{1}{4}\right) \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \]
    4. metadata-eval100.0

      \[\leadsto \left(\left(\sqrt{2} \cdot \color{blue}{0.25}\right) \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \]
  4. Applied egg-rr100.0%

    \[\leadsto \left(\color{blue}{\left(\sqrt{2} \cdot 0.25\right)} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \]
  5. Step-by-step derivation
    1. *-commutativeN/A

      \[\leadsto \color{blue}{\left(1 - v \cdot v\right) \cdot \left(\left(\sqrt{2} \cdot \frac{1}{4}\right) \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right)} \]
    2. *-lowering-*.f64N/A

      \[\leadsto \color{blue}{\left(1 - v \cdot v\right) \cdot \left(\left(\sqrt{2} \cdot \frac{1}{4}\right) \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right)} \]
    3. --lowering--.f64N/A

      \[\leadsto \color{blue}{\left(1 - v \cdot v\right)} \cdot \left(\left(\sqrt{2} \cdot \frac{1}{4}\right) \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \]
    4. *-lowering-*.f64N/A

      \[\leadsto \left(1 - \color{blue}{v \cdot v}\right) \cdot \left(\left(\sqrt{2} \cdot \frac{1}{4}\right) \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \]
    5. *-commutativeN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\color{blue}{\left(\frac{1}{4} \cdot \sqrt{2}\right)} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \]
    6. associate-*l*N/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \color{blue}{\left(\frac{1}{4} \cdot \left(\sqrt{2} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right)\right)} \]
    7. *-lowering-*.f64N/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \color{blue}{\left(\frac{1}{4} \cdot \left(\sqrt{2} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right)\right)} \]
    8. metadata-evalN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \left(\sqrt{2} \cdot \sqrt{\color{blue}{1 \cdot 1} - 3 \cdot \left(v \cdot v\right)}\right)\right) \]
    9. *-commutativeN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \left(\sqrt{2} \cdot \sqrt{1 \cdot 1 - \color{blue}{\left(v \cdot v\right) \cdot 3}}\right)\right) \]
    10. *-rgt-identityN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \left(\sqrt{2} \cdot \sqrt{1 \cdot 1 - \color{blue}{\left(\left(v \cdot v\right) \cdot 3\right) \cdot 1}}\right)\right) \]
    11. sqrt-unprodN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \color{blue}{\sqrt{2 \cdot \left(1 \cdot 1 - \left(\left(v \cdot v\right) \cdot 3\right) \cdot 1\right)}}\right) \]
    12. sqrt-lowering-sqrt.f64N/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \color{blue}{\sqrt{2 \cdot \left(1 \cdot 1 - \left(\left(v \cdot v\right) \cdot 3\right) \cdot 1\right)}}\right) \]
    13. *-lowering-*.f64N/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \sqrt{\color{blue}{2 \cdot \left(1 \cdot 1 - \left(\left(v \cdot v\right) \cdot 3\right) \cdot 1\right)}}\right) \]
    14. metadata-evalN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \sqrt{2 \cdot \left(\color{blue}{1} - \left(\left(v \cdot v\right) \cdot 3\right) \cdot 1\right)}\right) \]
    15. sub-negN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \sqrt{2 \cdot \color{blue}{\left(1 + \left(\mathsf{neg}\left(\left(\left(v \cdot v\right) \cdot 3\right) \cdot 1\right)\right)\right)}}\right) \]
    16. *-rgt-identityN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \sqrt{2 \cdot \left(1 + \left(\mathsf{neg}\left(\color{blue}{\left(v \cdot v\right) \cdot 3}\right)\right)\right)}\right) \]
    17. *-commutativeN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \sqrt{2 \cdot \left(1 + \left(\mathsf{neg}\left(\color{blue}{3 \cdot \left(v \cdot v\right)}\right)\right)\right)}\right) \]
  6. Applied egg-rr100.0%

    \[\leadsto \color{blue}{\left(1 - v \cdot v\right) \cdot \left(0.25 \cdot \sqrt{2 \cdot \mathsf{fma}\left(v \cdot v, -3, 1\right)}\right)} \]
  7. Step-by-step derivation
    1. *-commutativeN/A

      \[\leadsto \color{blue}{\left(\frac{1}{4} \cdot \sqrt{2 \cdot \left(\left(v \cdot v\right) \cdot -3 + 1\right)}\right) \cdot \left(1 - v \cdot v\right)} \]
    2. *-commutativeN/A

      \[\leadsto \color{blue}{\left(\sqrt{2 \cdot \left(\left(v \cdot v\right) \cdot -3 + 1\right)} \cdot \frac{1}{4}\right)} \cdot \left(1 - v \cdot v\right) \]
    3. distribute-rgt-inN/A

      \[\leadsto \left(\sqrt{\color{blue}{\left(\left(v \cdot v\right) \cdot -3\right) \cdot 2 + 1 \cdot 2}} \cdot \frac{1}{4}\right) \cdot \left(1 - v \cdot v\right) \]
    4. metadata-evalN/A

      \[\leadsto \left(\sqrt{\left(\left(v \cdot v\right) \cdot -3\right) \cdot 2 + \color{blue}{2}} \cdot \frac{1}{4}\right) \cdot \left(1 - v \cdot v\right) \]
    5. associate-*l*N/A

      \[\leadsto \left(\sqrt{\color{blue}{\left(v \cdot v\right) \cdot \left(-3 \cdot 2\right)} + 2} \cdot \frac{1}{4}\right) \cdot \left(1 - v \cdot v\right) \]
    6. metadata-evalN/A

      \[\leadsto \left(\sqrt{\left(v \cdot v\right) \cdot \color{blue}{-6} + 2} \cdot \frac{1}{4}\right) \cdot \left(1 - v \cdot v\right) \]
    7. associate-*r*N/A

      \[\leadsto \left(\sqrt{\color{blue}{v \cdot \left(v \cdot -6\right)} + 2} \cdot \frac{1}{4}\right) \cdot \left(1 - v \cdot v\right) \]
    8. *-commutativeN/A

      \[\leadsto \color{blue}{\left(\frac{1}{4} \cdot \sqrt{v \cdot \left(v \cdot -6\right) + 2}\right)} \cdot \left(1 - v \cdot v\right) \]
    9. /-rgt-identityN/A

      \[\leadsto \color{blue}{\frac{\frac{1}{4} \cdot \sqrt{v \cdot \left(v \cdot -6\right) + 2}}{1}} \cdot \left(1 - v \cdot v\right) \]
    10. associate-/r/N/A

      \[\leadsto \color{blue}{\frac{\frac{1}{4} \cdot \sqrt{v \cdot \left(v \cdot -6\right) + 2}}{\frac{1}{1 - v \cdot v}}} \]
    11. frac-2negN/A

      \[\leadsto \color{blue}{\frac{\mathsf{neg}\left(\frac{1}{4} \cdot \sqrt{v \cdot \left(v \cdot -6\right) + 2}\right)}{\mathsf{neg}\left(\frac{1}{1 - v \cdot v}\right)}} \]
    12. /-lowering-/.f64N/A

      \[\leadsto \color{blue}{\frac{\mathsf{neg}\left(\frac{1}{4} \cdot \sqrt{v \cdot \left(v \cdot -6\right) + 2}\right)}{\mathsf{neg}\left(\frac{1}{1 - v \cdot v}\right)}} \]
  8. Applied egg-rr100.0%

    \[\leadsto \color{blue}{\frac{\sqrt{\mathsf{fma}\left(v, v \cdot -6, 2\right)} \cdot -0.25}{\frac{1}{\mathsf{fma}\left(v, v, -1\right)}}} \]
  9. Add Preprocessing

Alternative 2: 100.0% accurate, 1.7× speedup?

\[\begin{array}{l} \\ \left(\sqrt{\mathsf{fma}\left(v, v \cdot -6, 2\right)} \cdot -0.25\right) \cdot \mathsf{fma}\left(v, v, -1\right) \end{array} \]
(FPCore (v)
 :precision binary64
 (* (* (sqrt (fma v (* v -6.0) 2.0)) -0.25) (fma v v -1.0)))
double code(double v) {
	return (sqrt(fma(v, (v * -6.0), 2.0)) * -0.25) * fma(v, v, -1.0);
}
function code(v)
	return Float64(Float64(sqrt(fma(v, Float64(v * -6.0), 2.0)) * -0.25) * fma(v, v, -1.0))
end
code[v_] := N[(N[(N[Sqrt[N[(v * N[(v * -6.0), $MachinePrecision] + 2.0), $MachinePrecision]], $MachinePrecision] * -0.25), $MachinePrecision] * N[(v * v + -1.0), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\left(\sqrt{\mathsf{fma}\left(v, v \cdot -6, 2\right)} \cdot -0.25\right) \cdot \mathsf{fma}\left(v, v, -1\right)
\end{array}
Derivation
  1. Initial program 100.0%

    \[\left(\frac{\sqrt{2}}{4} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. div-invN/A

      \[\leadsto \left(\color{blue}{\left(\sqrt{2} \cdot \frac{1}{4}\right)} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \]
    2. *-lowering-*.f64N/A

      \[\leadsto \left(\color{blue}{\left(\sqrt{2} \cdot \frac{1}{4}\right)} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \]
    3. sqrt-lowering-sqrt.f64N/A

      \[\leadsto \left(\left(\color{blue}{\sqrt{2}} \cdot \frac{1}{4}\right) \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \]
    4. metadata-eval100.0

      \[\leadsto \left(\left(\sqrt{2} \cdot \color{blue}{0.25}\right) \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \]
  4. Applied egg-rr100.0%

    \[\leadsto \left(\color{blue}{\left(\sqrt{2} \cdot 0.25\right)} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \]
  5. Step-by-step derivation
    1. *-commutativeN/A

      \[\leadsto \color{blue}{\left(1 - v \cdot v\right) \cdot \left(\left(\sqrt{2} \cdot \frac{1}{4}\right) \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right)} \]
    2. *-lowering-*.f64N/A

      \[\leadsto \color{blue}{\left(1 - v \cdot v\right) \cdot \left(\left(\sqrt{2} \cdot \frac{1}{4}\right) \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right)} \]
    3. --lowering--.f64N/A

      \[\leadsto \color{blue}{\left(1 - v \cdot v\right)} \cdot \left(\left(\sqrt{2} \cdot \frac{1}{4}\right) \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \]
    4. *-lowering-*.f64N/A

      \[\leadsto \left(1 - \color{blue}{v \cdot v}\right) \cdot \left(\left(\sqrt{2} \cdot \frac{1}{4}\right) \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \]
    5. *-commutativeN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\color{blue}{\left(\frac{1}{4} \cdot \sqrt{2}\right)} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \]
    6. associate-*l*N/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \color{blue}{\left(\frac{1}{4} \cdot \left(\sqrt{2} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right)\right)} \]
    7. *-lowering-*.f64N/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \color{blue}{\left(\frac{1}{4} \cdot \left(\sqrt{2} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right)\right)} \]
    8. metadata-evalN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \left(\sqrt{2} \cdot \sqrt{\color{blue}{1 \cdot 1} - 3 \cdot \left(v \cdot v\right)}\right)\right) \]
    9. *-commutativeN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \left(\sqrt{2} \cdot \sqrt{1 \cdot 1 - \color{blue}{\left(v \cdot v\right) \cdot 3}}\right)\right) \]
    10. *-rgt-identityN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \left(\sqrt{2} \cdot \sqrt{1 \cdot 1 - \color{blue}{\left(\left(v \cdot v\right) \cdot 3\right) \cdot 1}}\right)\right) \]
    11. sqrt-unprodN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \color{blue}{\sqrt{2 \cdot \left(1 \cdot 1 - \left(\left(v \cdot v\right) \cdot 3\right) \cdot 1\right)}}\right) \]
    12. sqrt-lowering-sqrt.f64N/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \color{blue}{\sqrt{2 \cdot \left(1 \cdot 1 - \left(\left(v \cdot v\right) \cdot 3\right) \cdot 1\right)}}\right) \]
    13. *-lowering-*.f64N/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \sqrt{\color{blue}{2 \cdot \left(1 \cdot 1 - \left(\left(v \cdot v\right) \cdot 3\right) \cdot 1\right)}}\right) \]
    14. metadata-evalN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \sqrt{2 \cdot \left(\color{blue}{1} - \left(\left(v \cdot v\right) \cdot 3\right) \cdot 1\right)}\right) \]
    15. sub-negN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \sqrt{2 \cdot \color{blue}{\left(1 + \left(\mathsf{neg}\left(\left(\left(v \cdot v\right) \cdot 3\right) \cdot 1\right)\right)\right)}}\right) \]
    16. *-rgt-identityN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \sqrt{2 \cdot \left(1 + \left(\mathsf{neg}\left(\color{blue}{\left(v \cdot v\right) \cdot 3}\right)\right)\right)}\right) \]
    17. *-commutativeN/A

      \[\leadsto \left(1 - v \cdot v\right) \cdot \left(\frac{1}{4} \cdot \sqrt{2 \cdot \left(1 + \left(\mathsf{neg}\left(\color{blue}{3 \cdot \left(v \cdot v\right)}\right)\right)\right)}\right) \]
  6. Applied egg-rr100.0%

    \[\leadsto \color{blue}{\left(1 - v \cdot v\right) \cdot \left(0.25 \cdot \sqrt{2 \cdot \mathsf{fma}\left(v \cdot v, -3, 1\right)}\right)} \]
  7. Step-by-step derivation
    1. *-commutativeN/A

      \[\leadsto \color{blue}{\left(\frac{1}{4} \cdot \sqrt{2 \cdot \left(\left(v \cdot v\right) \cdot -3 + 1\right)}\right) \cdot \left(1 - v \cdot v\right)} \]
    2. associate-*l*N/A

      \[\leadsto \color{blue}{\frac{1}{4} \cdot \left(\sqrt{2 \cdot \left(\left(v \cdot v\right) \cdot -3 + 1\right)} \cdot \left(1 - v \cdot v\right)\right)} \]
    3. distribute-rgt-inN/A

      \[\leadsto \frac{1}{4} \cdot \left(\sqrt{\color{blue}{\left(\left(v \cdot v\right) \cdot -3\right) \cdot 2 + 1 \cdot 2}} \cdot \left(1 - v \cdot v\right)\right) \]
    4. metadata-evalN/A

      \[\leadsto \frac{1}{4} \cdot \left(\sqrt{\left(\left(v \cdot v\right) \cdot -3\right) \cdot 2 + \color{blue}{2}} \cdot \left(1 - v \cdot v\right)\right) \]
    5. associate-*l*N/A

      \[\leadsto \frac{1}{4} \cdot \left(\sqrt{\color{blue}{\left(v \cdot v\right) \cdot \left(-3 \cdot 2\right)} + 2} \cdot \left(1 - v \cdot v\right)\right) \]
    6. metadata-evalN/A

      \[\leadsto \frac{1}{4} \cdot \left(\sqrt{\left(v \cdot v\right) \cdot \color{blue}{-6} + 2} \cdot \left(1 - v \cdot v\right)\right) \]
    7. associate-*r*N/A

      \[\leadsto \frac{1}{4} \cdot \left(\sqrt{\color{blue}{v \cdot \left(v \cdot -6\right)} + 2} \cdot \left(1 - v \cdot v\right)\right) \]
    8. associate-*l*N/A

      \[\leadsto \color{blue}{\left(\frac{1}{4} \cdot \sqrt{v \cdot \left(v \cdot -6\right) + 2}\right) \cdot \left(1 - v \cdot v\right)} \]
    9. /-rgt-identityN/A

      \[\leadsto \color{blue}{\frac{\frac{1}{4} \cdot \sqrt{v \cdot \left(v \cdot -6\right) + 2}}{1}} \cdot \left(1 - v \cdot v\right) \]
    10. frac-2negN/A

      \[\leadsto \color{blue}{\frac{\mathsf{neg}\left(\frac{1}{4} \cdot \sqrt{v \cdot \left(v \cdot -6\right) + 2}\right)}{\mathsf{neg}\left(1\right)}} \cdot \left(1 - v \cdot v\right) \]
    11. metadata-evalN/A

      \[\leadsto \frac{\mathsf{neg}\left(\frac{1}{4} \cdot \sqrt{v \cdot \left(v \cdot -6\right) + 2}\right)}{\color{blue}{-1}} \cdot \left(1 - v \cdot v\right) \]
    12. div-invN/A

      \[\leadsto \color{blue}{\left(\left(\mathsf{neg}\left(\frac{1}{4} \cdot \sqrt{v \cdot \left(v \cdot -6\right) + 2}\right)\right) \cdot \frac{1}{-1}\right)} \cdot \left(1 - v \cdot v\right) \]
    13. metadata-evalN/A

      \[\leadsto \left(\left(\mathsf{neg}\left(\frac{1}{4} \cdot \sqrt{v \cdot \left(v \cdot -6\right) + 2}\right)\right) \cdot \color{blue}{-1}\right) \cdot \left(1 - v \cdot v\right) \]
  8. Applied egg-rr100.0%

    \[\leadsto \color{blue}{\mathsf{fma}\left(v, v, -1\right) \cdot \left(\sqrt{\mathsf{fma}\left(v, v \cdot -6, 2\right)} \cdot -0.25\right)} \]
  9. Final simplification100.0%

    \[\leadsto \left(\sqrt{\mathsf{fma}\left(v, v \cdot -6, 2\right)} \cdot -0.25\right) \cdot \mathsf{fma}\left(v, v, -1\right) \]
  10. Add Preprocessing

Alternative 3: 99.5% accurate, 2.3× speedup?

\[\begin{array}{l} \\ \sqrt{2} \cdot \mathsf{fma}\left(v \cdot v, -0.625, 0.25\right) \end{array} \]
(FPCore (v) :precision binary64 (* (sqrt 2.0) (fma (* v v) -0.625 0.25)))
double code(double v) {
	return sqrt(2.0) * fma((v * v), -0.625, 0.25);
}
function code(v)
	return Float64(sqrt(2.0) * fma(Float64(v * v), -0.625, 0.25))
end
code[v_] := N[(N[Sqrt[2.0], $MachinePrecision] * N[(N[(v * v), $MachinePrecision] * -0.625 + 0.25), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\sqrt{2} \cdot \mathsf{fma}\left(v \cdot v, -0.625, 0.25\right)
\end{array}
Derivation
  1. Initial program 100.0%

    \[\left(\frac{\sqrt{2}}{4} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \]
  2. Add Preprocessing
  3. Applied egg-rr100.0%

    \[\leadsto \left(\frac{\sqrt{2}}{4} \cdot \color{blue}{\left(\sqrt{\mathsf{fma}\left(v \cdot \left(v \cdot \left(v \cdot v\right)\right), -9, 1\right)} \cdot \sqrt{\frac{1}{\mathsf{fma}\left(v, 3 \cdot v, 1\right)}}\right)}\right) \cdot \left(1 - v \cdot v\right) \]
  4. Taylor expanded in v around 0

    \[\leadsto \color{blue}{\frac{1}{4} \cdot \sqrt{2} + \frac{1}{4} \cdot \left({v}^{2} \cdot \left(\frac{-3}{2} \cdot \sqrt{2} + -1 \cdot \sqrt{2}\right)\right)} \]
  5. Step-by-step derivation
    1. +-commutativeN/A

      \[\leadsto \color{blue}{\frac{1}{4} \cdot \left({v}^{2} \cdot \left(\frac{-3}{2} \cdot \sqrt{2} + -1 \cdot \sqrt{2}\right)\right) + \frac{1}{4} \cdot \sqrt{2}} \]
    2. *-commutativeN/A

      \[\leadsto \frac{1}{4} \cdot \color{blue}{\left(\left(\frac{-3}{2} \cdot \sqrt{2} + -1 \cdot \sqrt{2}\right) \cdot {v}^{2}\right)} + \frac{1}{4} \cdot \sqrt{2} \]
    3. associate-*r*N/A

      \[\leadsto \color{blue}{\left(\frac{1}{4} \cdot \left(\frac{-3}{2} \cdot \sqrt{2} + -1 \cdot \sqrt{2}\right)\right) \cdot {v}^{2}} + \frac{1}{4} \cdot \sqrt{2} \]
    4. *-commutativeN/A

      \[\leadsto \color{blue}{\left(\left(\frac{-3}{2} \cdot \sqrt{2} + -1 \cdot \sqrt{2}\right) \cdot \frac{1}{4}\right)} \cdot {v}^{2} + \frac{1}{4} \cdot \sqrt{2} \]
    5. distribute-rgt-outN/A

      \[\leadsto \left(\color{blue}{\left(\sqrt{2} \cdot \left(\frac{-3}{2} + -1\right)\right)} \cdot \frac{1}{4}\right) \cdot {v}^{2} + \frac{1}{4} \cdot \sqrt{2} \]
    6. metadata-evalN/A

      \[\leadsto \left(\left(\sqrt{2} \cdot \color{blue}{\frac{-5}{2}}\right) \cdot \frac{1}{4}\right) \cdot {v}^{2} + \frac{1}{4} \cdot \sqrt{2} \]
    7. associate-*l*N/A

      \[\leadsto \color{blue}{\left(\sqrt{2} \cdot \left(\frac{-5}{2} \cdot \frac{1}{4}\right)\right)} \cdot {v}^{2} + \frac{1}{4} \cdot \sqrt{2} \]
    8. metadata-evalN/A

      \[\leadsto \left(\sqrt{2} \cdot \color{blue}{\frac{-5}{8}}\right) \cdot {v}^{2} + \frac{1}{4} \cdot \sqrt{2} \]
    9. associate-*l*N/A

      \[\leadsto \color{blue}{\sqrt{2} \cdot \left(\frac{-5}{8} \cdot {v}^{2}\right)} + \frac{1}{4} \cdot \sqrt{2} \]
    10. *-commutativeN/A

      \[\leadsto \sqrt{2} \cdot \left(\frac{-5}{8} \cdot {v}^{2}\right) + \color{blue}{\sqrt{2} \cdot \frac{1}{4}} \]
    11. distribute-lft-outN/A

      \[\leadsto \color{blue}{\sqrt{2} \cdot \left(\frac{-5}{8} \cdot {v}^{2} + \frac{1}{4}\right)} \]
    12. *-lowering-*.f64N/A

      \[\leadsto \color{blue}{\sqrt{2} \cdot \left(\frac{-5}{8} \cdot {v}^{2} + \frac{1}{4}\right)} \]
    13. sqrt-lowering-sqrt.f64N/A

      \[\leadsto \color{blue}{\sqrt{2}} \cdot \left(\frac{-5}{8} \cdot {v}^{2} + \frac{1}{4}\right) \]
    14. *-commutativeN/A

      \[\leadsto \sqrt{2} \cdot \left(\color{blue}{{v}^{2} \cdot \frac{-5}{8}} + \frac{1}{4}\right) \]
    15. accelerator-lowering-fma.f64N/A

      \[\leadsto \sqrt{2} \cdot \color{blue}{\mathsf{fma}\left({v}^{2}, \frac{-5}{8}, \frac{1}{4}\right)} \]
  6. Simplified99.8%

    \[\leadsto \color{blue}{\sqrt{2} \cdot \mathsf{fma}\left(v \cdot v, -0.625, 0.25\right)} \]
  7. Add Preprocessing

Alternative 4: 98.9% accurate, 3.9× speedup?

\[\begin{array}{l} \\ \sqrt{2} \cdot 0.25 \end{array} \]
(FPCore (v) :precision binary64 (* (sqrt 2.0) 0.25))
double code(double v) {
	return sqrt(2.0) * 0.25;
}
real(8) function code(v)
    real(8), intent (in) :: v
    code = sqrt(2.0d0) * 0.25d0
end function
public static double code(double v) {
	return Math.sqrt(2.0) * 0.25;
}
def code(v):
	return math.sqrt(2.0) * 0.25
function code(v)
	return Float64(sqrt(2.0) * 0.25)
end
function tmp = code(v)
	tmp = sqrt(2.0) * 0.25;
end
code[v_] := N[(N[Sqrt[2.0], $MachinePrecision] * 0.25), $MachinePrecision]
\begin{array}{l}

\\
\sqrt{2} \cdot 0.25
\end{array}
Derivation
  1. Initial program 100.0%

    \[\left(\frac{\sqrt{2}}{4} \cdot \sqrt{1 - 3 \cdot \left(v \cdot v\right)}\right) \cdot \left(1 - v \cdot v\right) \]
  2. Add Preprocessing
  3. Taylor expanded in v around 0

    \[\leadsto \color{blue}{\frac{1}{4} \cdot \sqrt{2}} \]
  4. Step-by-step derivation
    1. *-lowering-*.f64N/A

      \[\leadsto \color{blue}{\frac{1}{4} \cdot \sqrt{2}} \]
    2. sqrt-lowering-sqrt.f6499.4

      \[\leadsto 0.25 \cdot \color{blue}{\sqrt{2}} \]
  5. Simplified99.4%

    \[\leadsto \color{blue}{0.25 \cdot \sqrt{2}} \]
  6. Final simplification99.4%

    \[\leadsto \sqrt{2} \cdot 0.25 \]
  7. Add Preprocessing

Reproduce

?
herbie shell --seed 2024204 
(FPCore (v)
  :name "Falkner and Boettcher, Appendix B, 2"
  :precision binary64
  (* (* (/ (sqrt 2.0) 4.0) (sqrt (- 1.0 (* 3.0 (* v v))))) (- 1.0 (* v v))))