Falkner and Boettcher, Appendix B, 2

Percentage Accurate: 100.0% → 100.0%
Time: 6.5s
Alternatives: 4
Speedup: 1.0×

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, 1.0× speedup?

\[\begin{array}{l} \\ \sqrt{0.125} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \end{array} \]
(FPCore (v)
 :precision binary64
 (* (sqrt 0.125) (* (sqrt (+ 1.0 (* -3.0 (* v v)))) (- 1.0 (* v v)))))
double code(double v) {
	return sqrt(0.125) * (sqrt((1.0 + (-3.0 * (v * v)))) * (1.0 - (v * v)));
}
real(8) function code(v)
    real(8), intent (in) :: v
    code = sqrt(0.125d0) * (sqrt((1.0d0 + ((-3.0d0) * (v * v)))) * (1.0d0 - (v * v)))
end function
public static double code(double v) {
	return Math.sqrt(0.125) * (Math.sqrt((1.0 + (-3.0 * (v * v)))) * (1.0 - (v * v)));
}
def code(v):
	return math.sqrt(0.125) * (math.sqrt((1.0 + (-3.0 * (v * v)))) * (1.0 - (v * v)))
function code(v)
	return Float64(sqrt(0.125) * Float64(sqrt(Float64(1.0 + Float64(-3.0 * Float64(v * v)))) * Float64(1.0 - Float64(v * v))))
end
function tmp = code(v)
	tmp = sqrt(0.125) * (sqrt((1.0 + (-3.0 * (v * v)))) * (1.0 - (v * v)));
end
code[v_] := N[(N[Sqrt[0.125], $MachinePrecision] * N[(N[Sqrt[N[(1.0 + N[(-3.0 * N[(v * v), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] * N[(1.0 - N[(v * v), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\sqrt{0.125} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\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. Step-by-step derivation
    1. associate-*l*100.0%

      \[\leadsto \color{blue}{\frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 - 3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right)} \]
    2. sqr-neg100.0%

      \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 - 3 \cdot \color{blue}{\left(\left(-v\right) \cdot \left(-v\right)\right)}} \cdot \left(1 - v \cdot v\right)\right) \]
    3. cancel-sign-sub-inv100.0%

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

      \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 + \color{blue}{-3} \cdot \left(\left(-v\right) \cdot \left(-v\right)\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    5. sqr-neg100.0%

      \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 + -3 \cdot \color{blue}{\left(v \cdot v\right)}} \cdot \left(1 - v \cdot v\right)\right) \]
  3. Simplified100.0%

    \[\leadsto \color{blue}{\frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right)} \]
  4. Add Preprocessing
  5. Step-by-step derivation
    1. add-log-exp100.0%

      \[\leadsto \color{blue}{\log \left(e^{\frac{\sqrt{2}}{4}}\right)} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    2. *-un-lft-identity100.0%

      \[\leadsto \log \color{blue}{\left(1 \cdot e^{\frac{\sqrt{2}}{4}}\right)} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    3. log-prod100.0%

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

      \[\leadsto \left(\color{blue}{0} + \log \left(e^{\frac{\sqrt{2}}{4}}\right)\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    5. add-log-exp100.0%

      \[\leadsto \left(0 + \color{blue}{\frac{\sqrt{2}}{4}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    6. add-sqr-sqrt98.4%

      \[\leadsto \left(0 + \color{blue}{\sqrt{\frac{\sqrt{2}}{4}} \cdot \sqrt{\frac{\sqrt{2}}{4}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    7. sqrt-unprod100.0%

      \[\leadsto \left(0 + \color{blue}{\sqrt{\frac{\sqrt{2}}{4} \cdot \frac{\sqrt{2}}{4}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    8. frac-times100.0%

      \[\leadsto \left(0 + \sqrt{\color{blue}{\frac{\sqrt{2} \cdot \sqrt{2}}{4 \cdot 4}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    9. rem-square-sqrt100.0%

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

      \[\leadsto \left(0 + \sqrt{\frac{2}{\color{blue}{16}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    11. metadata-eval100.0%

      \[\leadsto \left(0 + \sqrt{\color{blue}{0.125}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
  6. Applied egg-rr100.0%

    \[\leadsto \color{blue}{\left(0 + \sqrt{0.125}\right)} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
  7. Step-by-step derivation
    1. +-lft-identity100.0%

      \[\leadsto \color{blue}{\sqrt{0.125}} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
  8. Simplified100.0%

    \[\leadsto \color{blue}{\sqrt{0.125}} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
  9. Add Preprocessing

Alternative 2: 99.6% accurate, 2.0× speedup?

\[\begin{array}{l} \\ \sqrt{0.125} \cdot \left(1 + \left(v \cdot v\right) \cdot -2.5\right) \end{array} \]
(FPCore (v) :precision binary64 (* (sqrt 0.125) (+ 1.0 (* (* v v) -2.5))))
double code(double v) {
	return sqrt(0.125) * (1.0 + ((v * v) * -2.5));
}
real(8) function code(v)
    real(8), intent (in) :: v
    code = sqrt(0.125d0) * (1.0d0 + ((v * v) * (-2.5d0)))
end function
public static double code(double v) {
	return Math.sqrt(0.125) * (1.0 + ((v * v) * -2.5));
}
def code(v):
	return math.sqrt(0.125) * (1.0 + ((v * v) * -2.5))
function code(v)
	return Float64(sqrt(0.125) * Float64(1.0 + Float64(Float64(v * v) * -2.5)))
end
function tmp = code(v)
	tmp = sqrt(0.125) * (1.0 + ((v * v) * -2.5));
end
code[v_] := N[(N[Sqrt[0.125], $MachinePrecision] * N[(1.0 + N[(N[(v * v), $MachinePrecision] * -2.5), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\sqrt{0.125} \cdot \left(1 + \left(v \cdot v\right) \cdot -2.5\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. Step-by-step derivation
    1. associate-*l*100.0%

      \[\leadsto \color{blue}{\frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 - 3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right)} \]
    2. sqr-neg100.0%

      \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 - 3 \cdot \color{blue}{\left(\left(-v\right) \cdot \left(-v\right)\right)}} \cdot \left(1 - v \cdot v\right)\right) \]
    3. cancel-sign-sub-inv100.0%

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

      \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 + \color{blue}{-3} \cdot \left(\left(-v\right) \cdot \left(-v\right)\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    5. sqr-neg100.0%

      \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 + -3 \cdot \color{blue}{\left(v \cdot v\right)}} \cdot \left(1 - v \cdot v\right)\right) \]
  3. Simplified100.0%

    \[\leadsto \color{blue}{\frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right)} \]
  4. Add Preprocessing
  5. Taylor expanded in v around 0 99.6%

    \[\leadsto \frac{\sqrt{2}}{4} \cdot \color{blue}{\left(1 + -2.5 \cdot {v}^{2}\right)} \]
  6. Step-by-step derivation
    1. *-commutative99.6%

      \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(1 + \color{blue}{{v}^{2} \cdot -2.5}\right) \]
  7. Simplified99.6%

    \[\leadsto \frac{\sqrt{2}}{4} \cdot \color{blue}{\left(1 + {v}^{2} \cdot -2.5\right)} \]
  8. Step-by-step derivation
    1. pow299.6%

      \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(1 + \color{blue}{\left(v \cdot v\right)} \cdot -2.5\right) \]
  9. Applied egg-rr99.6%

    \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(1 + \color{blue}{\left(v \cdot v\right)} \cdot -2.5\right) \]
  10. Step-by-step derivation
    1. add-log-exp100.0%

      \[\leadsto \color{blue}{\log \left(e^{\frac{\sqrt{2}}{4}}\right)} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    2. *-un-lft-identity100.0%

      \[\leadsto \log \color{blue}{\left(1 \cdot e^{\frac{\sqrt{2}}{4}}\right)} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    3. log-prod100.0%

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

      \[\leadsto \left(\color{blue}{0} + \log \left(e^{\frac{\sqrt{2}}{4}}\right)\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    5. add-log-exp100.0%

      \[\leadsto \left(0 + \color{blue}{\frac{\sqrt{2}}{4}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    6. add-sqr-sqrt98.4%

      \[\leadsto \left(0 + \color{blue}{\sqrt{\frac{\sqrt{2}}{4}} \cdot \sqrt{\frac{\sqrt{2}}{4}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    7. sqrt-unprod100.0%

      \[\leadsto \left(0 + \color{blue}{\sqrt{\frac{\sqrt{2}}{4} \cdot \frac{\sqrt{2}}{4}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    8. frac-times100.0%

      \[\leadsto \left(0 + \sqrt{\color{blue}{\frac{\sqrt{2} \cdot \sqrt{2}}{4 \cdot 4}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    9. rem-square-sqrt100.0%

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

      \[\leadsto \left(0 + \sqrt{\frac{2}{\color{blue}{16}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    11. metadata-eval100.0%

      \[\leadsto \left(0 + \sqrt{\color{blue}{0.125}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
  11. Applied egg-rr99.6%

    \[\leadsto \color{blue}{\left(0 + \sqrt{0.125}\right)} \cdot \left(1 + \left(v \cdot v\right) \cdot -2.5\right) \]
  12. Step-by-step derivation
    1. +-lft-identity100.0%

      \[\leadsto \color{blue}{\sqrt{0.125}} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
  13. Simplified99.6%

    \[\leadsto \color{blue}{\sqrt{0.125}} \cdot \left(1 + \left(v \cdot v\right) \cdot -2.5\right) \]
  14. Add Preprocessing

Alternative 3: 99.1% accurate, 2.0× speedup?

\[\begin{array}{l} \\ \sqrt{0.125} \cdot \left(1 - v \cdot v\right) \end{array} \]
(FPCore (v) :precision binary64 (* (sqrt 0.125) (- 1.0 (* v v))))
double code(double v) {
	return sqrt(0.125) * (1.0 - (v * v));
}
real(8) function code(v)
    real(8), intent (in) :: v
    code = sqrt(0.125d0) * (1.0d0 - (v * v))
end function
public static double code(double v) {
	return Math.sqrt(0.125) * (1.0 - (v * v));
}
def code(v):
	return math.sqrt(0.125) * (1.0 - (v * v))
function code(v)
	return Float64(sqrt(0.125) * Float64(1.0 - Float64(v * v)))
end
function tmp = code(v)
	tmp = sqrt(0.125) * (1.0 - (v * v));
end
code[v_] := N[(N[Sqrt[0.125], $MachinePrecision] * N[(1.0 - N[(v * v), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\sqrt{0.125} \cdot \left(1 - v \cdot v\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. Step-by-step derivation
    1. associate-*l*100.0%

      \[\leadsto \color{blue}{\frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 - 3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right)} \]
    2. sqr-neg100.0%

      \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 - 3 \cdot \color{blue}{\left(\left(-v\right) \cdot \left(-v\right)\right)}} \cdot \left(1 - v \cdot v\right)\right) \]
    3. cancel-sign-sub-inv100.0%

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

      \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 + \color{blue}{-3} \cdot \left(\left(-v\right) \cdot \left(-v\right)\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    5. sqr-neg100.0%

      \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 + -3 \cdot \color{blue}{\left(v \cdot v\right)}} \cdot \left(1 - v \cdot v\right)\right) \]
  3. Simplified100.0%

    \[\leadsto \color{blue}{\frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right)} \]
  4. Add Preprocessing
  5. Taylor expanded in v around 0 98.6%

    \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(\color{blue}{1} \cdot \left(1 - v \cdot v\right)\right) \]
  6. Step-by-step derivation
    1. add-log-exp100.0%

      \[\leadsto \color{blue}{\log \left(e^{\frac{\sqrt{2}}{4}}\right)} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    2. *-un-lft-identity100.0%

      \[\leadsto \log \color{blue}{\left(1 \cdot e^{\frac{\sqrt{2}}{4}}\right)} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    3. log-prod100.0%

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

      \[\leadsto \left(\color{blue}{0} + \log \left(e^{\frac{\sqrt{2}}{4}}\right)\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    5. add-log-exp100.0%

      \[\leadsto \left(0 + \color{blue}{\frac{\sqrt{2}}{4}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    6. add-sqr-sqrt98.4%

      \[\leadsto \left(0 + \color{blue}{\sqrt{\frac{\sqrt{2}}{4}} \cdot \sqrt{\frac{\sqrt{2}}{4}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    7. sqrt-unprod100.0%

      \[\leadsto \left(0 + \color{blue}{\sqrt{\frac{\sqrt{2}}{4} \cdot \frac{\sqrt{2}}{4}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    8. frac-times100.0%

      \[\leadsto \left(0 + \sqrt{\color{blue}{\frac{\sqrt{2} \cdot \sqrt{2}}{4 \cdot 4}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    9. rem-square-sqrt100.0%

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

      \[\leadsto \left(0 + \sqrt{\frac{2}{\color{blue}{16}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    11. metadata-eval100.0%

      \[\leadsto \left(0 + \sqrt{\color{blue}{0.125}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
  7. Applied egg-rr98.6%

    \[\leadsto \color{blue}{\left(0 + \sqrt{0.125}\right)} \cdot \left(1 \cdot \left(1 - v \cdot v\right)\right) \]
  8. Step-by-step derivation
    1. +-lft-identity100.0%

      \[\leadsto \color{blue}{\sqrt{0.125}} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
  9. Simplified98.6%

    \[\leadsto \color{blue}{\sqrt{0.125}} \cdot \left(1 \cdot \left(1 - v \cdot v\right)\right) \]
  10. Final simplification98.6%

    \[\leadsto \sqrt{0.125} \cdot \left(1 - v \cdot v\right) \]
  11. Add Preprocessing

Alternative 4: 99.1% accurate, 2.1× speedup?

\[\begin{array}{l} \\ \sqrt{0.125} \end{array} \]
(FPCore (v) :precision binary64 (sqrt 0.125))
double code(double v) {
	return sqrt(0.125);
}
real(8) function code(v)
    real(8), intent (in) :: v
    code = sqrt(0.125d0)
end function
public static double code(double v) {
	return Math.sqrt(0.125);
}
def code(v):
	return math.sqrt(0.125)
function code(v)
	return sqrt(0.125)
end
function tmp = code(v)
	tmp = sqrt(0.125);
end
code[v_] := N[Sqrt[0.125], $MachinePrecision]
\begin{array}{l}

\\
\sqrt{0.125}
\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. Step-by-step derivation
    1. associate-*l*100.0%

      \[\leadsto \color{blue}{\frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 - 3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right)} \]
    2. sqr-neg100.0%

      \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 - 3 \cdot \color{blue}{\left(\left(-v\right) \cdot \left(-v\right)\right)}} \cdot \left(1 - v \cdot v\right)\right) \]
    3. cancel-sign-sub-inv100.0%

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

      \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 + \color{blue}{-3} \cdot \left(\left(-v\right) \cdot \left(-v\right)\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    5. sqr-neg100.0%

      \[\leadsto \frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 + -3 \cdot \color{blue}{\left(v \cdot v\right)}} \cdot \left(1 - v \cdot v\right)\right) \]
  3. Simplified100.0%

    \[\leadsto \color{blue}{\frac{\sqrt{2}}{4} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right)} \]
  4. Add Preprocessing
  5. Step-by-step derivation
    1. add-log-exp100.0%

      \[\leadsto \color{blue}{\log \left(e^{\frac{\sqrt{2}}{4}}\right)} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    2. *-un-lft-identity100.0%

      \[\leadsto \log \color{blue}{\left(1 \cdot e^{\frac{\sqrt{2}}{4}}\right)} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    3. log-prod100.0%

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

      \[\leadsto \left(\color{blue}{0} + \log \left(e^{\frac{\sqrt{2}}{4}}\right)\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    5. add-log-exp100.0%

      \[\leadsto \left(0 + \color{blue}{\frac{\sqrt{2}}{4}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    6. add-sqr-sqrt98.4%

      \[\leadsto \left(0 + \color{blue}{\sqrt{\frac{\sqrt{2}}{4}} \cdot \sqrt{\frac{\sqrt{2}}{4}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    7. sqrt-unprod100.0%

      \[\leadsto \left(0 + \color{blue}{\sqrt{\frac{\sqrt{2}}{4} \cdot \frac{\sqrt{2}}{4}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    8. frac-times100.0%

      \[\leadsto \left(0 + \sqrt{\color{blue}{\frac{\sqrt{2} \cdot \sqrt{2}}{4 \cdot 4}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    9. rem-square-sqrt100.0%

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

      \[\leadsto \left(0 + \sqrt{\frac{2}{\color{blue}{16}}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
    11. metadata-eval100.0%

      \[\leadsto \left(0 + \sqrt{\color{blue}{0.125}}\right) \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
  6. Applied egg-rr100.0%

    \[\leadsto \color{blue}{\left(0 + \sqrt{0.125}\right)} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
  7. Step-by-step derivation
    1. +-lft-identity100.0%

      \[\leadsto \color{blue}{\sqrt{0.125}} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
  8. Simplified100.0%

    \[\leadsto \color{blue}{\sqrt{0.125}} \cdot \left(\sqrt{1 + -3 \cdot \left(v \cdot v\right)} \cdot \left(1 - v \cdot v\right)\right) \]
  9. Taylor expanded in v around 0 98.6%

    \[\leadsto \color{blue}{\sqrt{0.125}} \]
  10. Add Preprocessing

Reproduce

?
herbie shell --seed 2024149 
(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))))