Eccentricity of an ellipse

Percentage Accurate: 77.8% → 100.0%
Time: 5.5s
Alternatives: 4
Speedup: 211.0×

Specification

?
\[\left(0 \leq b \land b \leq a\right) \land a \leq 1\]
\[\begin{array}{l} \\ \sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|} \end{array} \]
(FPCore (a b)
 :precision binary64
 (sqrt (fabs (/ (- (* a a) (* b b)) (* a a)))))
double code(double a, double b) {
	return sqrt(fabs((((a * a) - (b * b)) / (a * a))));
}
real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = sqrt(abs((((a * a) - (b * b)) / (a * a))))
end function
public static double code(double a, double b) {
	return Math.sqrt(Math.abs((((a * a) - (b * b)) / (a * a))));
}
def code(a, b):
	return math.sqrt(math.fabs((((a * a) - (b * b)) / (a * a))))
function code(a, b)
	return sqrt(abs(Float64(Float64(Float64(a * a) - Float64(b * b)) / Float64(a * a))))
end
function tmp = code(a, b)
	tmp = sqrt(abs((((a * a) - (b * b)) / (a * a))));
end
code[a_, b_] := N[Sqrt[N[Abs[N[(N[(N[(a * a), $MachinePrecision] - N[(b * b), $MachinePrecision]), $MachinePrecision] / N[(a * a), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\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: 77.8% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|} \end{array} \]
(FPCore (a b)
 :precision binary64
 (sqrt (fabs (/ (- (* a a) (* b b)) (* a a)))))
double code(double a, double b) {
	return sqrt(fabs((((a * a) - (b * b)) / (a * a))));
}
real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = sqrt(abs((((a * a) - (b * b)) / (a * a))))
end function
public static double code(double a, double b) {
	return Math.sqrt(Math.abs((((a * a) - (b * b)) / (a * a))));
}
def code(a, b):
	return math.sqrt(math.fabs((((a * a) - (b * b)) / (a * a))))
function code(a, b)
	return sqrt(abs(Float64(Float64(Float64(a * a) - Float64(b * b)) / Float64(a * a))))
end
function tmp = code(a, b)
	tmp = sqrt(abs((((a * a) - (b * b)) / (a * a))));
end
code[a_, b_] := N[Sqrt[N[Abs[N[(N[(N[(a * a), $MachinePrecision] - N[(b * b), $MachinePrecision]), $MachinePrecision] / N[(a * a), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|}
\end{array}

Alternative 1: 100.0% accurate, 0.7× speedup?

\[\begin{array}{l} \\ e^{\mathsf{log1p}\left(-{\left(\frac{b}{a}\right)}^{2}\right) \cdot 0.5} \end{array} \]
(FPCore (a b) :precision binary64 (exp (* (log1p (- (pow (/ b a) 2.0))) 0.5)))
double code(double a, double b) {
	return exp((log1p(-pow((b / a), 2.0)) * 0.5));
}
public static double code(double a, double b) {
	return Math.exp((Math.log1p(-Math.pow((b / a), 2.0)) * 0.5));
}
def code(a, b):
	return math.exp((math.log1p(-math.pow((b / a), 2.0)) * 0.5))
function code(a, b)
	return exp(Float64(log1p(Float64(-(Float64(b / a) ^ 2.0))) * 0.5))
end
code[a_, b_] := N[Exp[N[(N[Log[1 + (-N[Power[N[(b / a), $MachinePrecision], 2.0], $MachinePrecision])], $MachinePrecision] * 0.5), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
e^{\mathsf{log1p}\left(-{\left(\frac{b}{a}\right)}^{2}\right) \cdot 0.5}
\end{array}
Derivation
  1. Initial program 74.2%

    \[\sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|} \]
  2. Step-by-step derivation
    1. sqr-neg74.2%

      \[\leadsto \sqrt{\left|\frac{a \cdot a - \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{a \cdot a}\right|} \]
    2. fabs-div74.2%

      \[\leadsto \sqrt{\color{blue}{\frac{\left|a \cdot a - \left(-b\right) \cdot \left(-b\right)\right|}{\left|a \cdot a\right|}}} \]
    3. sqr-neg74.2%

      \[\leadsto \sqrt{\frac{\left|a \cdot a - \color{blue}{b \cdot b}\right|}{\left|a \cdot a\right|}} \]
    4. fabs-sub74.2%

      \[\leadsto \sqrt{\frac{\color{blue}{\left|b \cdot b - a \cdot a\right|}}{\left|a \cdot a\right|}} \]
    5. sqr-neg74.2%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{\left(-a\right) \cdot \left(-a\right)}\right|}} \]
    6. distribute-rgt-neg-out74.2%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{-\left(-a\right) \cdot a}\right|}} \]
    7. fabs-neg74.2%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\color{blue}{\left|\left(-a\right) \cdot a\right|}}} \]
    8. fabs-div74.2%

      \[\leadsto \sqrt{\color{blue}{\left|\frac{b \cdot b - a \cdot a}{\left(-a\right) \cdot a}\right|}} \]
    9. cancel-sign-sub-inv74.2%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{b \cdot b + \left(-a\right) \cdot a}}{\left(-a\right) \cdot a}\right|} \]
    10. +-commutative74.2%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a + b \cdot b}}{\left(-a\right) \cdot a}\right|} \]
    11. sqr-neg74.2%

      \[\leadsto \sqrt{\left|\frac{\left(-a\right) \cdot a + \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
    12. cancel-sign-sub-inv74.2%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a - b \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
    13. div-sub74.2%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{\left(-a\right) \cdot a}{\left(-a\right) \cdot a} - \frac{b \cdot \left(-b\right)}{\left(-a\right) \cdot a}}\right|} \]
  3. Simplified75.0%

    \[\leadsto \color{blue}{\sqrt{\left|1 - b \cdot \frac{b}{a \cdot a}\right|}} \]
  4. Add Preprocessing
  5. Step-by-step derivation
    1. pow1/275.0%

      \[\leadsto \color{blue}{{\left(\left|1 - b \cdot \frac{b}{a \cdot a}\right|\right)}^{0.5}} \]
    2. pow-to-exp75.0%

      \[\leadsto \color{blue}{e^{\log \left(\left|1 - b \cdot \frac{b}{a \cdot a}\right|\right) \cdot 0.5}} \]
    3. add-sqr-sqrt74.2%

      \[\leadsto e^{\log \left(\left|\color{blue}{\sqrt{1 - b \cdot \frac{b}{a \cdot a}} \cdot \sqrt{1 - b \cdot \frac{b}{a \cdot a}}}\right|\right) \cdot 0.5} \]
    4. fabs-sqr74.2%

      \[\leadsto e^{\log \color{blue}{\left(\sqrt{1 - b \cdot \frac{b}{a \cdot a}} \cdot \sqrt{1 - b \cdot \frac{b}{a \cdot a}}\right)} \cdot 0.5} \]
    5. add-sqr-sqrt74.2%

      \[\leadsto e^{\log \color{blue}{\left(1 - b \cdot \frac{b}{a \cdot a}\right)} \cdot 0.5} \]
    6. sub-neg74.2%

      \[\leadsto e^{\log \color{blue}{\left(1 + \left(-b \cdot \frac{b}{a \cdot a}\right)\right)} \cdot 0.5} \]
    7. log1p-define74.2%

      \[\leadsto e^{\color{blue}{\mathsf{log1p}\left(-b \cdot \frac{b}{a \cdot a}\right)} \cdot 0.5} \]
    8. associate-*r/74.2%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b \cdot b}{a \cdot a}}\right) \cdot 0.5} \]
    9. frac-times100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b}{a} \cdot \frac{b}{a}}\right) \cdot 0.5} \]
    10. pow2100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{{\left(\frac{b}{a}\right)}^{2}}\right) \cdot 0.5} \]
  6. Applied egg-rr100.0%

    \[\leadsto \color{blue}{e^{\mathsf{log1p}\left(-{\left(\frac{b}{a}\right)}^{2}\right) \cdot 0.5}} \]
  7. Add Preprocessing

Alternative 2: 100.0% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \sqrt{1 - {\left(\frac{b}{a}\right)}^{2}} \end{array} \]
(FPCore (a b) :precision binary64 (sqrt (- 1.0 (pow (/ b a) 2.0))))
double code(double a, double b) {
	return sqrt((1.0 - pow((b / a), 2.0)));
}
real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = sqrt((1.0d0 - ((b / a) ** 2.0d0)))
end function
public static double code(double a, double b) {
	return Math.sqrt((1.0 - Math.pow((b / a), 2.0)));
}
def code(a, b):
	return math.sqrt((1.0 - math.pow((b / a), 2.0)))
function code(a, b)
	return sqrt(Float64(1.0 - (Float64(b / a) ^ 2.0)))
end
function tmp = code(a, b)
	tmp = sqrt((1.0 - ((b / a) ^ 2.0)));
end
code[a_, b_] := N[Sqrt[N[(1.0 - N[Power[N[(b / a), $MachinePrecision], 2.0], $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\sqrt{1 - {\left(\frac{b}{a}\right)}^{2}}
\end{array}
Derivation
  1. Initial program 74.2%

    \[\sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|} \]
  2. Step-by-step derivation
    1. sqr-neg74.2%

      \[\leadsto \sqrt{\left|\frac{a \cdot a - \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{a \cdot a}\right|} \]
    2. fabs-div74.2%

      \[\leadsto \sqrt{\color{blue}{\frac{\left|a \cdot a - \left(-b\right) \cdot \left(-b\right)\right|}{\left|a \cdot a\right|}}} \]
    3. sqr-neg74.2%

      \[\leadsto \sqrt{\frac{\left|a \cdot a - \color{blue}{b \cdot b}\right|}{\left|a \cdot a\right|}} \]
    4. fabs-sub74.2%

      \[\leadsto \sqrt{\frac{\color{blue}{\left|b \cdot b - a \cdot a\right|}}{\left|a \cdot a\right|}} \]
    5. sqr-neg74.2%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{\left(-a\right) \cdot \left(-a\right)}\right|}} \]
    6. distribute-rgt-neg-out74.2%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{-\left(-a\right) \cdot a}\right|}} \]
    7. fabs-neg74.2%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\color{blue}{\left|\left(-a\right) \cdot a\right|}}} \]
    8. fabs-div74.2%

      \[\leadsto \sqrt{\color{blue}{\left|\frac{b \cdot b - a \cdot a}{\left(-a\right) \cdot a}\right|}} \]
    9. cancel-sign-sub-inv74.2%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{b \cdot b + \left(-a\right) \cdot a}}{\left(-a\right) \cdot a}\right|} \]
    10. +-commutative74.2%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a + b \cdot b}}{\left(-a\right) \cdot a}\right|} \]
    11. sqr-neg74.2%

      \[\leadsto \sqrt{\left|\frac{\left(-a\right) \cdot a + \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
    12. cancel-sign-sub-inv74.2%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a - b \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
    13. div-sub74.2%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{\left(-a\right) \cdot a}{\left(-a\right) \cdot a} - \frac{b \cdot \left(-b\right)}{\left(-a\right) \cdot a}}\right|} \]
  3. Simplified75.0%

    \[\leadsto \color{blue}{\sqrt{\left|1 - b \cdot \frac{b}{a \cdot a}\right|}} \]
  4. Add Preprocessing
  5. Step-by-step derivation
    1. fabs-sub75.0%

      \[\leadsto \sqrt{\color{blue}{\left|b \cdot \frac{b}{a \cdot a} - 1\right|}} \]
    2. sub-neg75.0%

      \[\leadsto \sqrt{\left|\color{blue}{b \cdot \frac{b}{a \cdot a} + \left(-1\right)}\right|} \]
    3. metadata-eval75.0%

      \[\leadsto \sqrt{\left|b \cdot \frac{b}{a \cdot a} + \color{blue}{-1}\right|} \]
    4. associate-*r/74.2%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{b \cdot b}{a \cdot a}} + -1\right|} \]
    5. frac-times100.0%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{b}{a} \cdot \frac{b}{a}} + -1\right|} \]
    6. fma-undefine100.0%

      \[\leadsto \sqrt{\left|\color{blue}{\mathsf{fma}\left(\frac{b}{a}, \frac{b}{a}, -1\right)}\right|} \]
    7. add-exp-log100.0%

      \[\leadsto \color{blue}{e^{\log \left(\sqrt{\left|\mathsf{fma}\left(\frac{b}{a}, \frac{b}{a}, -1\right)\right|}\right)}} \]
    8. add-sqr-sqrt99.9%

      \[\leadsto e^{\log \color{blue}{\left(\sqrt{\sqrt{\left|\mathsf{fma}\left(\frac{b}{a}, \frac{b}{a}, -1\right)\right|}} \cdot \sqrt{\sqrt{\left|\mathsf{fma}\left(\frac{b}{a}, \frac{b}{a}, -1\right)\right|}}\right)}} \]
    9. log-prod99.9%

      \[\leadsto e^{\color{blue}{\log \left(\sqrt{\sqrt{\left|\mathsf{fma}\left(\frac{b}{a}, \frac{b}{a}, -1\right)\right|}}\right) + \log \left(\sqrt{\sqrt{\left|\mathsf{fma}\left(\frac{b}{a}, \frac{b}{a}, -1\right)\right|}}\right)}} \]
  6. Applied egg-rr100.0%

    \[\leadsto \color{blue}{e^{0.5 \cdot \mathsf{log1p}\left(-{\left(\frac{b}{a}\right)}^{2}\right)}} \]
  7. Step-by-step derivation
    1. *-commutative100.0%

      \[\leadsto e^{\color{blue}{\mathsf{log1p}\left(-{\left(\frac{b}{a}\right)}^{2}\right) \cdot 0.5}} \]
    2. log1p-undefine100.0%

      \[\leadsto e^{\color{blue}{\log \left(1 + \left(-{\left(\frac{b}{a}\right)}^{2}\right)\right)} \cdot 0.5} \]
    3. +-commutative100.0%

      \[\leadsto e^{\log \color{blue}{\left(\left(-{\left(\frac{b}{a}\right)}^{2}\right) + 1\right)} \cdot 0.5} \]
    4. metadata-eval100.0%

      \[\leadsto e^{\log \left(\left(-{\left(\frac{b}{a}\right)}^{2}\right) + \color{blue}{\left(--1\right)}\right) \cdot 0.5} \]
    5. distribute-neg-in100.0%

      \[\leadsto e^{\log \color{blue}{\left(-\left({\left(\frac{b}{a}\right)}^{2} + -1\right)\right)} \cdot 0.5} \]
    6. exp-to-pow100.0%

      \[\leadsto \color{blue}{{\left(-\left({\left(\frac{b}{a}\right)}^{2} + -1\right)\right)}^{0.5}} \]
    7. unpow1/2100.0%

      \[\leadsto \color{blue}{\sqrt{-\left({\left(\frac{b}{a}\right)}^{2} + -1\right)}} \]
    8. distribute-neg-in100.0%

      \[\leadsto \sqrt{\color{blue}{\left(-{\left(\frac{b}{a}\right)}^{2}\right) + \left(--1\right)}} \]
    9. metadata-eval100.0%

      \[\leadsto \sqrt{\left(-{\left(\frac{b}{a}\right)}^{2}\right) + \color{blue}{1}} \]
    10. +-commutative100.0%

      \[\leadsto \sqrt{\color{blue}{1 + \left(-{\left(\frac{b}{a}\right)}^{2}\right)}} \]
    11. sub-neg100.0%

      \[\leadsto \sqrt{\color{blue}{1 - {\left(\frac{b}{a}\right)}^{2}}} \]
  8. Simplified100.0%

    \[\leadsto \color{blue}{\sqrt{1 - {\left(\frac{b}{a}\right)}^{2}}} \]
  9. Add Preprocessing

Alternative 3: 99.1% accurate, 2.0× speedup?

\[\begin{array}{l} \\ 1 + {\left(\frac{b}{a}\right)}^{2} \cdot -0.5 \end{array} \]
(FPCore (a b) :precision binary64 (+ 1.0 (* (pow (/ b a) 2.0) -0.5)))
double code(double a, double b) {
	return 1.0 + (pow((b / a), 2.0) * -0.5);
}
real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = 1.0d0 + (((b / a) ** 2.0d0) * (-0.5d0))
end function
public static double code(double a, double b) {
	return 1.0 + (Math.pow((b / a), 2.0) * -0.5);
}
def code(a, b):
	return 1.0 + (math.pow((b / a), 2.0) * -0.5)
function code(a, b)
	return Float64(1.0 + Float64((Float64(b / a) ^ 2.0) * -0.5))
end
function tmp = code(a, b)
	tmp = 1.0 + (((b / a) ^ 2.0) * -0.5);
end
code[a_, b_] := N[(1.0 + N[(N[Power[N[(b / a), $MachinePrecision], 2.0], $MachinePrecision] * -0.5), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
1 + {\left(\frac{b}{a}\right)}^{2} \cdot -0.5
\end{array}
Derivation
  1. Initial program 74.2%

    \[\sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|} \]
  2. Step-by-step derivation
    1. sqr-neg74.2%

      \[\leadsto \sqrt{\left|\frac{a \cdot a - \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{a \cdot a}\right|} \]
    2. fabs-div74.2%

      \[\leadsto \sqrt{\color{blue}{\frac{\left|a \cdot a - \left(-b\right) \cdot \left(-b\right)\right|}{\left|a \cdot a\right|}}} \]
    3. sqr-neg74.2%

      \[\leadsto \sqrt{\frac{\left|a \cdot a - \color{blue}{b \cdot b}\right|}{\left|a \cdot a\right|}} \]
    4. fabs-sub74.2%

      \[\leadsto \sqrt{\frac{\color{blue}{\left|b \cdot b - a \cdot a\right|}}{\left|a \cdot a\right|}} \]
    5. sqr-neg74.2%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{\left(-a\right) \cdot \left(-a\right)}\right|}} \]
    6. distribute-rgt-neg-out74.2%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{-\left(-a\right) \cdot a}\right|}} \]
    7. fabs-neg74.2%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\color{blue}{\left|\left(-a\right) \cdot a\right|}}} \]
    8. fabs-div74.2%

      \[\leadsto \sqrt{\color{blue}{\left|\frac{b \cdot b - a \cdot a}{\left(-a\right) \cdot a}\right|}} \]
    9. cancel-sign-sub-inv74.2%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{b \cdot b + \left(-a\right) \cdot a}}{\left(-a\right) \cdot a}\right|} \]
    10. +-commutative74.2%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a + b \cdot b}}{\left(-a\right) \cdot a}\right|} \]
    11. sqr-neg74.2%

      \[\leadsto \sqrt{\left|\frac{\left(-a\right) \cdot a + \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
    12. cancel-sign-sub-inv74.2%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a - b \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
    13. div-sub74.2%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{\left(-a\right) \cdot a}{\left(-a\right) \cdot a} - \frac{b \cdot \left(-b\right)}{\left(-a\right) \cdot a}}\right|} \]
  3. Simplified75.0%

    \[\leadsto \color{blue}{\sqrt{\left|1 - b \cdot \frac{b}{a \cdot a}\right|}} \]
  4. Add Preprocessing
  5. Step-by-step derivation
    1. pow1/275.0%

      \[\leadsto \color{blue}{{\left(\left|1 - b \cdot \frac{b}{a \cdot a}\right|\right)}^{0.5}} \]
    2. pow-to-exp75.0%

      \[\leadsto \color{blue}{e^{\log \left(\left|1 - b \cdot \frac{b}{a \cdot a}\right|\right) \cdot 0.5}} \]
    3. add-sqr-sqrt74.2%

      \[\leadsto e^{\log \left(\left|\color{blue}{\sqrt{1 - b \cdot \frac{b}{a \cdot a}} \cdot \sqrt{1 - b \cdot \frac{b}{a \cdot a}}}\right|\right) \cdot 0.5} \]
    4. fabs-sqr74.2%

      \[\leadsto e^{\log \color{blue}{\left(\sqrt{1 - b \cdot \frac{b}{a \cdot a}} \cdot \sqrt{1 - b \cdot \frac{b}{a \cdot a}}\right)} \cdot 0.5} \]
    5. add-sqr-sqrt74.2%

      \[\leadsto e^{\log \color{blue}{\left(1 - b \cdot \frac{b}{a \cdot a}\right)} \cdot 0.5} \]
    6. sub-neg74.2%

      \[\leadsto e^{\log \color{blue}{\left(1 + \left(-b \cdot \frac{b}{a \cdot a}\right)\right)} \cdot 0.5} \]
    7. log1p-define74.2%

      \[\leadsto e^{\color{blue}{\mathsf{log1p}\left(-b \cdot \frac{b}{a \cdot a}\right)} \cdot 0.5} \]
    8. associate-*r/74.2%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b \cdot b}{a \cdot a}}\right) \cdot 0.5} \]
    9. frac-times100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b}{a} \cdot \frac{b}{a}}\right) \cdot 0.5} \]
    10. pow2100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{{\left(\frac{b}{a}\right)}^{2}}\right) \cdot 0.5} \]
  6. Applied egg-rr100.0%

    \[\leadsto \color{blue}{e^{\mathsf{log1p}\left(-{\left(\frac{b}{a}\right)}^{2}\right) \cdot 0.5}} \]
  7. Taylor expanded in b around 0 73.7%

    \[\leadsto \color{blue}{1 + -0.5 \cdot \frac{{b}^{2}}{{a}^{2}}} \]
  8. Step-by-step derivation
    1. +-commutative73.7%

      \[\leadsto \color{blue}{-0.5 \cdot \frac{{b}^{2}}{{a}^{2}} + 1} \]
    2. fma-define73.7%

      \[\leadsto \color{blue}{\mathsf{fma}\left(-0.5, \frac{{b}^{2}}{{a}^{2}}, 1\right)} \]
    3. unpow273.7%

      \[\leadsto \mathsf{fma}\left(-0.5, \frac{\color{blue}{b \cdot b}}{{a}^{2}}, 1\right) \]
    4. unpow273.7%

      \[\leadsto \mathsf{fma}\left(-0.5, \frac{b \cdot b}{\color{blue}{a \cdot a}}, 1\right) \]
    5. times-frac99.3%

      \[\leadsto \mathsf{fma}\left(-0.5, \color{blue}{\frac{b}{a} \cdot \frac{b}{a}}, 1\right) \]
    6. unpow299.3%

      \[\leadsto \mathsf{fma}\left(-0.5, \color{blue}{{\left(\frac{b}{a}\right)}^{2}}, 1\right) \]
  9. Simplified99.3%

    \[\leadsto \color{blue}{\mathsf{fma}\left(-0.5, {\left(\frac{b}{a}\right)}^{2}, 1\right)} \]
  10. Step-by-step derivation
    1. fma-undefine99.3%

      \[\leadsto \color{blue}{-0.5 \cdot {\left(\frac{b}{a}\right)}^{2} + 1} \]
  11. Applied egg-rr99.3%

    \[\leadsto \color{blue}{-0.5 \cdot {\left(\frac{b}{a}\right)}^{2} + 1} \]
  12. Final simplification99.3%

    \[\leadsto 1 + {\left(\frac{b}{a}\right)}^{2} \cdot -0.5 \]
  13. Add Preprocessing

Alternative 4: 98.0% accurate, 211.0× speedup?

\[\begin{array}{l} \\ 1 \end{array} \]
(FPCore (a b) :precision binary64 1.0)
double code(double a, double b) {
	return 1.0;
}
real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = 1.0d0
end function
public static double code(double a, double b) {
	return 1.0;
}
def code(a, b):
	return 1.0
function code(a, b)
	return 1.0
end
function tmp = code(a, b)
	tmp = 1.0;
end
code[a_, b_] := 1.0
\begin{array}{l}

\\
1
\end{array}
Derivation
  1. Initial program 74.2%

    \[\sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|} \]
  2. Step-by-step derivation
    1. sqr-neg74.2%

      \[\leadsto \sqrt{\left|\frac{a \cdot a - \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{a \cdot a}\right|} \]
    2. fabs-div74.2%

      \[\leadsto \sqrt{\color{blue}{\frac{\left|a \cdot a - \left(-b\right) \cdot \left(-b\right)\right|}{\left|a \cdot a\right|}}} \]
    3. sqr-neg74.2%

      \[\leadsto \sqrt{\frac{\left|a \cdot a - \color{blue}{b \cdot b}\right|}{\left|a \cdot a\right|}} \]
    4. fabs-sub74.2%

      \[\leadsto \sqrt{\frac{\color{blue}{\left|b \cdot b - a \cdot a\right|}}{\left|a \cdot a\right|}} \]
    5. sqr-neg74.2%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{\left(-a\right) \cdot \left(-a\right)}\right|}} \]
    6. distribute-rgt-neg-out74.2%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{-\left(-a\right) \cdot a}\right|}} \]
    7. fabs-neg74.2%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\color{blue}{\left|\left(-a\right) \cdot a\right|}}} \]
    8. fabs-div74.2%

      \[\leadsto \sqrt{\color{blue}{\left|\frac{b \cdot b - a \cdot a}{\left(-a\right) \cdot a}\right|}} \]
    9. cancel-sign-sub-inv74.2%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{b \cdot b + \left(-a\right) \cdot a}}{\left(-a\right) \cdot a}\right|} \]
    10. +-commutative74.2%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a + b \cdot b}}{\left(-a\right) \cdot a}\right|} \]
    11. sqr-neg74.2%

      \[\leadsto \sqrt{\left|\frac{\left(-a\right) \cdot a + \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
    12. cancel-sign-sub-inv74.2%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a - b \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
    13. div-sub74.2%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{\left(-a\right) \cdot a}{\left(-a\right) \cdot a} - \frac{b \cdot \left(-b\right)}{\left(-a\right) \cdot a}}\right|} \]
  3. Simplified75.0%

    \[\leadsto \color{blue}{\sqrt{\left|1 - b \cdot \frac{b}{a \cdot a}\right|}} \]
  4. Add Preprocessing
  5. Step-by-step derivation
    1. pow1/275.0%

      \[\leadsto \color{blue}{{\left(\left|1 - b \cdot \frac{b}{a \cdot a}\right|\right)}^{0.5}} \]
    2. pow-to-exp75.0%

      \[\leadsto \color{blue}{e^{\log \left(\left|1 - b \cdot \frac{b}{a \cdot a}\right|\right) \cdot 0.5}} \]
    3. add-sqr-sqrt74.2%

      \[\leadsto e^{\log \left(\left|\color{blue}{\sqrt{1 - b \cdot \frac{b}{a \cdot a}} \cdot \sqrt{1 - b \cdot \frac{b}{a \cdot a}}}\right|\right) \cdot 0.5} \]
    4. fabs-sqr74.2%

      \[\leadsto e^{\log \color{blue}{\left(\sqrt{1 - b \cdot \frac{b}{a \cdot a}} \cdot \sqrt{1 - b \cdot \frac{b}{a \cdot a}}\right)} \cdot 0.5} \]
    5. add-sqr-sqrt74.2%

      \[\leadsto e^{\log \color{blue}{\left(1 - b \cdot \frac{b}{a \cdot a}\right)} \cdot 0.5} \]
    6. sub-neg74.2%

      \[\leadsto e^{\log \color{blue}{\left(1 + \left(-b \cdot \frac{b}{a \cdot a}\right)\right)} \cdot 0.5} \]
    7. log1p-define74.2%

      \[\leadsto e^{\color{blue}{\mathsf{log1p}\left(-b \cdot \frac{b}{a \cdot a}\right)} \cdot 0.5} \]
    8. associate-*r/74.2%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b \cdot b}{a \cdot a}}\right) \cdot 0.5} \]
    9. frac-times100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b}{a} \cdot \frac{b}{a}}\right) \cdot 0.5} \]
    10. pow2100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{{\left(\frac{b}{a}\right)}^{2}}\right) \cdot 0.5} \]
  6. Applied egg-rr100.0%

    \[\leadsto \color{blue}{e^{\mathsf{log1p}\left(-{\left(\frac{b}{a}\right)}^{2}\right) \cdot 0.5}} \]
  7. Taylor expanded in b around 0 98.2%

    \[\leadsto \color{blue}{1} \]
  8. Add Preprocessing

Reproduce

?
herbie shell --seed 2024181 
(FPCore (a b)
  :name "Eccentricity of an ellipse"
  :precision binary64
  :pre (and (and (<= 0.0 b) (<= b a)) (<= a 1.0))
  (sqrt (fabs (/ (- (* a a) (* b b)) (* a a)))))