Eccentricity of an ellipse

Percentage Accurate: 77.4% → 100.0%
Time: 6.3s
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: 77.4% 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, 1.0× speedup?

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

\\
e^{\mathsf{log1p}\left(\frac{\frac{b}{\frac{a}{b}}}{-a}\right) \cdot 0.5}
\end{array}
Derivation
  1. Initial program 79.3%

    \[\sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|} \]
  2. Step-by-step derivation
    1. sqr-neg79.3%

      \[\leadsto \sqrt{\left|\frac{a \cdot a - \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{a \cdot a}\right|} \]
    2. fabs-div79.3%

      \[\leadsto \sqrt{\color{blue}{\frac{\left|a \cdot a - \left(-b\right) \cdot \left(-b\right)\right|}{\left|a \cdot a\right|}}} \]
    3. sqr-neg79.3%

      \[\leadsto \sqrt{\frac{\left|a \cdot a - \color{blue}{b \cdot b}\right|}{\left|a \cdot a\right|}} \]
    4. fabs-sub79.3%

      \[\leadsto \sqrt{\frac{\color{blue}{\left|b \cdot b - a \cdot a\right|}}{\left|a \cdot a\right|}} \]
    5. sqr-neg79.3%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{\left(-a\right) \cdot \left(-a\right)}\right|}} \]
    6. distribute-rgt-neg-out79.3%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{-\left(-a\right) \cdot a}\right|}} \]
    7. fabs-neg79.3%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\color{blue}{\left|\left(-a\right) \cdot a\right|}}} \]
    8. fabs-div79.3%

      \[\leadsto \sqrt{\color{blue}{\left|\frac{b \cdot b - a \cdot a}{\left(-a\right) \cdot a}\right|}} \]
    9. cancel-sign-sub-inv79.3%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{b \cdot b + \left(-a\right) \cdot a}}{\left(-a\right) \cdot a}\right|} \]
    10. +-commutative79.3%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a + b \cdot b}}{\left(-a\right) \cdot a}\right|} \]
    11. sqr-neg79.3%

      \[\leadsto \sqrt{\left|\frac{\left(-a\right) \cdot a + \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
    12. cancel-sign-sub-inv79.3%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a - b \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
  3. Simplified79.9%

    \[\leadsto \color{blue}{\sqrt{\left|1 - b \cdot \frac{b}{a \cdot a}\right|}} \]
  4. Add Preprocessing
  5. Step-by-step derivation
    1. pow1/279.9%

      \[\leadsto \color{blue}{{\left(\left|1 - b \cdot \frac{b}{a \cdot a}\right|\right)}^{0.5}} \]
    2. pow-to-exp79.9%

      \[\leadsto \color{blue}{e^{\log \left(\left|1 - b \cdot \frac{b}{a \cdot a}\right|\right) \cdot 0.5}} \]
    3. add-sqr-sqrt79.3%

      \[\leadsto e^{\log \left(\left|\color{blue}{\sqrt{1 - b \cdot \frac{b}{a \cdot a}} \cdot \sqrt{1 - b \cdot \frac{b}{a \cdot a}}}\right|\right) \cdot 0.5} \]
    4. fabs-sqr79.3%

      \[\leadsto e^{\log \color{blue}{\left(\sqrt{1 - b \cdot \frac{b}{a \cdot a}} \cdot \sqrt{1 - b \cdot \frac{b}{a \cdot a}}\right)} \cdot 0.5} \]
    5. add-sqr-sqrt79.3%

      \[\leadsto e^{\log \color{blue}{\left(1 - b \cdot \frac{b}{a \cdot a}\right)} \cdot 0.5} \]
    6. sub-neg79.3%

      \[\leadsto e^{\log \color{blue}{\left(1 + \left(-b \cdot \frac{b}{a \cdot a}\right)\right)} \cdot 0.5} \]
    7. log1p-define79.3%

      \[\leadsto e^{\color{blue}{\mathsf{log1p}\left(-b \cdot \frac{b}{a \cdot a}\right)} \cdot 0.5} \]
    8. associate-*r/79.3%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b \cdot b}{a \cdot a}}\right) \cdot 0.5} \]
    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. Step-by-step derivation
    1. unpow2100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b}{a} \cdot \frac{b}{a}}\right) \cdot 0.5} \]
    2. clear-num100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\frac{b}{a} \cdot \color{blue}{\frac{1}{\frac{a}{b}}}\right) \cdot 0.5} \]
    3. div-inv100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{\frac{b}{a}}{\frac{a}{b}}}\right) \cdot 0.5} \]
    4. associate-/l/100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b}{\frac{a}{b} \cdot a}}\right) \cdot 0.5} \]
    5. associate-/r*100.0%

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

    \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{\frac{b}{\frac{a}{b}}}{a}}\right) \cdot 0.5} \]
  9. Final simplification100.0%

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

Alternative 2: 100.0% accurate, 1.9× speedup?

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

\\
\sqrt{1 - \frac{\frac{b}{\frac{a}{b}}}{a}}
\end{array}
Derivation
  1. Initial program 79.3%

    \[\sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|} \]
  2. Step-by-step derivation
    1. sqr-neg79.3%

      \[\leadsto \sqrt{\left|\frac{a \cdot a - \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{a \cdot a}\right|} \]
    2. fabs-div79.3%

      \[\leadsto \sqrt{\color{blue}{\frac{\left|a \cdot a - \left(-b\right) \cdot \left(-b\right)\right|}{\left|a \cdot a\right|}}} \]
    3. sqr-neg79.3%

      \[\leadsto \sqrt{\frac{\left|a \cdot a - \color{blue}{b \cdot b}\right|}{\left|a \cdot a\right|}} \]
    4. fabs-sub79.3%

      \[\leadsto \sqrt{\frac{\color{blue}{\left|b \cdot b - a \cdot a\right|}}{\left|a \cdot a\right|}} \]
    5. sqr-neg79.3%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{\left(-a\right) \cdot \left(-a\right)}\right|}} \]
    6. distribute-rgt-neg-out79.3%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{-\left(-a\right) \cdot a}\right|}} \]
    7. fabs-neg79.3%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\color{blue}{\left|\left(-a\right) \cdot a\right|}}} \]
    8. fabs-div79.3%

      \[\leadsto \sqrt{\color{blue}{\left|\frac{b \cdot b - a \cdot a}{\left(-a\right) \cdot a}\right|}} \]
    9. cancel-sign-sub-inv79.3%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{b \cdot b + \left(-a\right) \cdot a}}{\left(-a\right) \cdot a}\right|} \]
    10. +-commutative79.3%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a + b \cdot b}}{\left(-a\right) \cdot a}\right|} \]
    11. sqr-neg79.3%

      \[\leadsto \sqrt{\left|\frac{\left(-a\right) \cdot a + \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
    12. cancel-sign-sub-inv79.3%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a - b \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
  3. Simplified79.9%

    \[\leadsto \color{blue}{\sqrt{\left|1 - b \cdot \frac{b}{a \cdot a}\right|}} \]
  4. Add Preprocessing
  5. Step-by-step derivation
    1. *-inverses79.3%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a}{a \cdot a}} - b \cdot \frac{b}{a \cdot a}\right|} \]
    2. associate-*r/79.3%

      \[\leadsto \sqrt{\left|\frac{a \cdot a}{a \cdot a} - \color{blue}{\frac{b \cdot b}{a \cdot a}}\right|} \]
    3. div-sub79.3%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a - b \cdot b}{a \cdot a}}\right|} \]
    4. difference-of-squares79.3%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(a + b\right) \cdot \left(a - b\right)}}{a \cdot a}\right|} \]
    5. times-frac100.0%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a + b}{a} \cdot \frac{a - b}{a}}\right|} \]
    6. +-commutative100.0%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{b + a}}{a} \cdot \frac{a - b}{a}\right|} \]
  6. Applied egg-rr100.0%

    \[\leadsto \sqrt{\left|\color{blue}{\frac{b + a}{a} \cdot \frac{a - b}{a}}\right|} \]
  7. Step-by-step derivation
    1. pow1/2100.0%

      \[\leadsto \color{blue}{{\left(\left|\frac{b + a}{a} \cdot \frac{a - b}{a}\right|\right)}^{0.5}} \]
    2. add-sqr-sqrt100.0%

      \[\leadsto {\left(\left|\color{blue}{\sqrt{\frac{b + a}{a} \cdot \frac{a - b}{a}} \cdot \sqrt{\frac{b + a}{a} \cdot \frac{a - b}{a}}}\right|\right)}^{0.5} \]
    3. fabs-sqr100.0%

      \[\leadsto {\color{blue}{\left(\sqrt{\frac{b + a}{a} \cdot \frac{a - b}{a}} \cdot \sqrt{\frac{b + a}{a} \cdot \frac{a - b}{a}}\right)}}^{0.5} \]
    4. add-sqr-sqrt100.0%

      \[\leadsto {\color{blue}{\left(\frac{b + a}{a} \cdot \frac{a - b}{a}\right)}}^{0.5} \]
    5. frac-times79.3%

      \[\leadsto {\color{blue}{\left(\frac{\left(b + a\right) \cdot \left(a - b\right)}{a \cdot a}\right)}}^{0.5} \]
    6. +-commutative79.3%

      \[\leadsto {\left(\frac{\color{blue}{\left(a + b\right)} \cdot \left(a - b\right)}{a \cdot a}\right)}^{0.5} \]
    7. difference-of-squares79.3%

      \[\leadsto {\left(\frac{\color{blue}{a \cdot a - b \cdot b}}{a \cdot a}\right)}^{0.5} \]
    8. pow279.3%

      \[\leadsto {\left(\frac{\color{blue}{{a}^{2}} - b \cdot b}{a \cdot a}\right)}^{0.5} \]
    9. pow279.3%

      \[\leadsto {\left(\frac{{a}^{2} - \color{blue}{{b}^{2}}}{a \cdot a}\right)}^{0.5} \]
    10. pow279.3%

      \[\leadsto {\left(\frac{{a}^{2} - {b}^{2}}{\color{blue}{{a}^{2}}}\right)}^{0.5} \]
  8. Applied egg-rr79.3%

    \[\leadsto \color{blue}{{\left(\frac{{a}^{2} - {b}^{2}}{{a}^{2}}\right)}^{0.5}} \]
  9. Step-by-step derivation
    1. unpow1/279.3%

      \[\leadsto \color{blue}{\sqrt{\frac{{a}^{2} - {b}^{2}}{{a}^{2}}}} \]
    2. unpow279.3%

      \[\leadsto \sqrt{\frac{{a}^{2} - {b}^{2}}{\color{blue}{a \cdot a}}} \]
    3. associate-/l/79.0%

      \[\leadsto \sqrt{\color{blue}{\frac{\frac{{a}^{2} - {b}^{2}}{a}}{a}}} \]
    4. div-sub79.0%

      \[\leadsto \sqrt{\frac{\color{blue}{\frac{{a}^{2}}{a} - \frac{{b}^{2}}{a}}}{a}} \]
    5. div-sub79.0%

      \[\leadsto \sqrt{\color{blue}{\frac{\frac{{a}^{2}}{a}}{a} - \frac{\frac{{b}^{2}}{a}}{a}}} \]
    6. associate-/r*79.3%

      \[\leadsto \sqrt{\color{blue}{\frac{{a}^{2}}{a \cdot a}} - \frac{\frac{{b}^{2}}{a}}{a}} \]
    7. unpow279.3%

      \[\leadsto \sqrt{\frac{{a}^{2}}{\color{blue}{{a}^{2}}} - \frac{\frac{{b}^{2}}{a}}{a}} \]
    8. *-inverses98.3%

      \[\leadsto \sqrt{\color{blue}{1} - \frac{\frac{{b}^{2}}{a}}{a}} \]
    9. unpow298.3%

      \[\leadsto \sqrt{1 - \frac{\frac{\color{blue}{b \cdot b}}{a}}{a}} \]
    10. associate-*r/100.0%

      \[\leadsto \sqrt{1 - \frac{\color{blue}{b \cdot \frac{b}{a}}}{a}} \]
    11. associate-*l/100.0%

      \[\leadsto \sqrt{1 - \color{blue}{\frac{b}{a} \cdot \frac{b}{a}}} \]
    12. unpow2100.0%

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

    \[\leadsto \color{blue}{\sqrt{1 - {\left(\frac{b}{a}\right)}^{2}}} \]
  11. Step-by-step derivation
    1. unpow2100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b}{a} \cdot \frac{b}{a}}\right) \cdot 0.5} \]
    2. clear-num100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\frac{b}{a} \cdot \color{blue}{\frac{1}{\frac{a}{b}}}\right) \cdot 0.5} \]
    3. div-inv100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{\frac{b}{a}}{\frac{a}{b}}}\right) \cdot 0.5} \]
    4. associate-/l/100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b}{\frac{a}{b} \cdot a}}\right) \cdot 0.5} \]
    5. associate-/r*100.0%

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

    \[\leadsto \sqrt{1 - \color{blue}{\frac{\frac{b}{\frac{a}{b}}}{a}}} \]
  13. Add Preprocessing

Alternative 3: 99.0% accurate, 1.9× speedup?

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

\\
e^{\frac{\frac{b}{\frac{a}{b}}}{a} \cdot -0.5}
\end{array}
Derivation
  1. Initial program 79.3%

    \[\sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|} \]
  2. Step-by-step derivation
    1. sqr-neg79.3%

      \[\leadsto \sqrt{\left|\frac{a \cdot a - \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{a \cdot a}\right|} \]
    2. fabs-div79.3%

      \[\leadsto \sqrt{\color{blue}{\frac{\left|a \cdot a - \left(-b\right) \cdot \left(-b\right)\right|}{\left|a \cdot a\right|}}} \]
    3. sqr-neg79.3%

      \[\leadsto \sqrt{\frac{\left|a \cdot a - \color{blue}{b \cdot b}\right|}{\left|a \cdot a\right|}} \]
    4. fabs-sub79.3%

      \[\leadsto \sqrt{\frac{\color{blue}{\left|b \cdot b - a \cdot a\right|}}{\left|a \cdot a\right|}} \]
    5. sqr-neg79.3%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{\left(-a\right) \cdot \left(-a\right)}\right|}} \]
    6. distribute-rgt-neg-out79.3%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{-\left(-a\right) \cdot a}\right|}} \]
    7. fabs-neg79.3%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\color{blue}{\left|\left(-a\right) \cdot a\right|}}} \]
    8. fabs-div79.3%

      \[\leadsto \sqrt{\color{blue}{\left|\frac{b \cdot b - a \cdot a}{\left(-a\right) \cdot a}\right|}} \]
    9. cancel-sign-sub-inv79.3%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{b \cdot b + \left(-a\right) \cdot a}}{\left(-a\right) \cdot a}\right|} \]
    10. +-commutative79.3%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a + b \cdot b}}{\left(-a\right) \cdot a}\right|} \]
    11. sqr-neg79.3%

      \[\leadsto \sqrt{\left|\frac{\left(-a\right) \cdot a + \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
    12. cancel-sign-sub-inv79.3%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a - b \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
  3. Simplified79.9%

    \[\leadsto \color{blue}{\sqrt{\left|1 - b \cdot \frac{b}{a \cdot a}\right|}} \]
  4. Add Preprocessing
  5. Step-by-step derivation
    1. pow1/279.9%

      \[\leadsto \color{blue}{{\left(\left|1 - b \cdot \frac{b}{a \cdot a}\right|\right)}^{0.5}} \]
    2. pow-to-exp79.9%

      \[\leadsto \color{blue}{e^{\log \left(\left|1 - b \cdot \frac{b}{a \cdot a}\right|\right) \cdot 0.5}} \]
    3. add-sqr-sqrt79.3%

      \[\leadsto e^{\log \left(\left|\color{blue}{\sqrt{1 - b \cdot \frac{b}{a \cdot a}} \cdot \sqrt{1 - b \cdot \frac{b}{a \cdot a}}}\right|\right) \cdot 0.5} \]
    4. fabs-sqr79.3%

      \[\leadsto e^{\log \color{blue}{\left(\sqrt{1 - b \cdot \frac{b}{a \cdot a}} \cdot \sqrt{1 - b \cdot \frac{b}{a \cdot a}}\right)} \cdot 0.5} \]
    5. add-sqr-sqrt79.3%

      \[\leadsto e^{\log \color{blue}{\left(1 - b \cdot \frac{b}{a \cdot a}\right)} \cdot 0.5} \]
    6. sub-neg79.3%

      \[\leadsto e^{\log \color{blue}{\left(1 + \left(-b \cdot \frac{b}{a \cdot a}\right)\right)} \cdot 0.5} \]
    7. log1p-define79.3%

      \[\leadsto e^{\color{blue}{\mathsf{log1p}\left(-b \cdot \frac{b}{a \cdot a}\right)} \cdot 0.5} \]
    8. associate-*r/79.3%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b \cdot b}{a \cdot a}}\right) \cdot 0.5} \]
    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 78.6%

    \[\leadsto e^{\color{blue}{-0.5 \cdot \frac{{b}^{2}}{{a}^{2}}}} \]
  8. Step-by-step derivation
    1. unpow278.6%

      \[\leadsto e^{-0.5 \cdot \frac{\color{blue}{b \cdot b}}{{a}^{2}}} \]
    2. unpow278.6%

      \[\leadsto e^{-0.5 \cdot \frac{b \cdot b}{\color{blue}{a \cdot a}}} \]
    3. times-frac98.2%

      \[\leadsto e^{-0.5 \cdot \color{blue}{\left(\frac{b}{a} \cdot \frac{b}{a}\right)}} \]
    4. unpow298.2%

      \[\leadsto e^{-0.5 \cdot \color{blue}{{\left(\frac{b}{a}\right)}^{2}}} \]
  9. Simplified98.2%

    \[\leadsto e^{\color{blue}{-0.5 \cdot {\left(\frac{b}{a}\right)}^{2}}} \]
  10. Step-by-step derivation
    1. unpow2100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b}{a} \cdot \frac{b}{a}}\right) \cdot 0.5} \]
    2. clear-num100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\frac{b}{a} \cdot \color{blue}{\frac{1}{\frac{a}{b}}}\right) \cdot 0.5} \]
    3. div-inv100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{\frac{b}{a}}{\frac{a}{b}}}\right) \cdot 0.5} \]
    4. associate-/l/100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b}{\frac{a}{b} \cdot a}}\right) \cdot 0.5} \]
    5. associate-/r*100.0%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{\frac{b}{\frac{a}{b}}}{a}}\right) \cdot 0.5} \]
  11. Applied egg-rr98.2%

    \[\leadsto e^{-0.5 \cdot \color{blue}{\frac{\frac{b}{\frac{a}{b}}}{a}}} \]
  12. Final simplification98.2%

    \[\leadsto e^{\frac{\frac{b}{\frac{a}{b}}}{a} \cdot -0.5} \]
  13. Add Preprocessing

Alternative 4: 97.9% 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 79.3%

    \[\sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|} \]
  2. Step-by-step derivation
    1. sqr-neg79.3%

      \[\leadsto \sqrt{\left|\frac{a \cdot a - \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{a \cdot a}\right|} \]
    2. fabs-div79.3%

      \[\leadsto \sqrt{\color{blue}{\frac{\left|a \cdot a - \left(-b\right) \cdot \left(-b\right)\right|}{\left|a \cdot a\right|}}} \]
    3. sqr-neg79.3%

      \[\leadsto \sqrt{\frac{\left|a \cdot a - \color{blue}{b \cdot b}\right|}{\left|a \cdot a\right|}} \]
    4. fabs-sub79.3%

      \[\leadsto \sqrt{\frac{\color{blue}{\left|b \cdot b - a \cdot a\right|}}{\left|a \cdot a\right|}} \]
    5. sqr-neg79.3%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{\left(-a\right) \cdot \left(-a\right)}\right|}} \]
    6. distribute-rgt-neg-out79.3%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\left|\color{blue}{-\left(-a\right) \cdot a}\right|}} \]
    7. fabs-neg79.3%

      \[\leadsto \sqrt{\frac{\left|b \cdot b - a \cdot a\right|}{\color{blue}{\left|\left(-a\right) \cdot a\right|}}} \]
    8. fabs-div79.3%

      \[\leadsto \sqrt{\color{blue}{\left|\frac{b \cdot b - a \cdot a}{\left(-a\right) \cdot a}\right|}} \]
    9. cancel-sign-sub-inv79.3%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{b \cdot b + \left(-a\right) \cdot a}}{\left(-a\right) \cdot a}\right|} \]
    10. +-commutative79.3%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a + b \cdot b}}{\left(-a\right) \cdot a}\right|} \]
    11. sqr-neg79.3%

      \[\leadsto \sqrt{\left|\frac{\left(-a\right) \cdot a + \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
    12. cancel-sign-sub-inv79.3%

      \[\leadsto \sqrt{\left|\frac{\color{blue}{\left(-a\right) \cdot a - b \cdot \left(-b\right)}}{\left(-a\right) \cdot a}\right|} \]
  3. Simplified79.9%

    \[\leadsto \color{blue}{\sqrt{\left|1 - b \cdot \frac{b}{a \cdot a}\right|}} \]
  4. Add Preprocessing
  5. Step-by-step derivation
    1. pow1/279.9%

      \[\leadsto \color{blue}{{\left(\left|1 - b \cdot \frac{b}{a \cdot a}\right|\right)}^{0.5}} \]
    2. pow-to-exp79.9%

      \[\leadsto \color{blue}{e^{\log \left(\left|1 - b \cdot \frac{b}{a \cdot a}\right|\right) \cdot 0.5}} \]
    3. add-sqr-sqrt79.3%

      \[\leadsto e^{\log \left(\left|\color{blue}{\sqrt{1 - b \cdot \frac{b}{a \cdot a}} \cdot \sqrt{1 - b \cdot \frac{b}{a \cdot a}}}\right|\right) \cdot 0.5} \]
    4. fabs-sqr79.3%

      \[\leadsto e^{\log \color{blue}{\left(\sqrt{1 - b \cdot \frac{b}{a \cdot a}} \cdot \sqrt{1 - b \cdot \frac{b}{a \cdot a}}\right)} \cdot 0.5} \]
    5. add-sqr-sqrt79.3%

      \[\leadsto e^{\log \color{blue}{\left(1 - b \cdot \frac{b}{a \cdot a}\right)} \cdot 0.5} \]
    6. sub-neg79.3%

      \[\leadsto e^{\log \color{blue}{\left(1 + \left(-b \cdot \frac{b}{a \cdot a}\right)\right)} \cdot 0.5} \]
    7. log1p-define79.3%

      \[\leadsto e^{\color{blue}{\mathsf{log1p}\left(-b \cdot \frac{b}{a \cdot a}\right)} \cdot 0.5} \]
    8. associate-*r/79.3%

      \[\leadsto e^{\mathsf{log1p}\left(-\color{blue}{\frac{b \cdot b}{a \cdot a}}\right) \cdot 0.5} \]
    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 78.6%

    \[\leadsto e^{\color{blue}{-0.5 \cdot \frac{{b}^{2}}{{a}^{2}}}} \]
  8. Step-by-step derivation
    1. unpow278.6%

      \[\leadsto e^{-0.5 \cdot \frac{\color{blue}{b \cdot b}}{{a}^{2}}} \]
    2. unpow278.6%

      \[\leadsto e^{-0.5 \cdot \frac{b \cdot b}{\color{blue}{a \cdot a}}} \]
    3. times-frac98.2%

      \[\leadsto e^{-0.5 \cdot \color{blue}{\left(\frac{b}{a} \cdot \frac{b}{a}\right)}} \]
    4. unpow298.2%

      \[\leadsto e^{-0.5 \cdot \color{blue}{{\left(\frac{b}{a}\right)}^{2}}} \]
  9. Simplified98.2%

    \[\leadsto e^{\color{blue}{-0.5 \cdot {\left(\frac{b}{a}\right)}^{2}}} \]
  10. Taylor expanded in b around 0 96.9%

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

Reproduce

?
herbie shell --seed 2024105 
(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)))))