Eccentricity of an ellipse

Percentage Accurate: 77.8% → 100.0%
Time: 9.0s
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, 1.0× speedup?

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

\\
\frac{\sqrt{a - b \cdot \frac{b}{a}}}{\sqrt{a}}
\end{array}
Derivation
  1. Initial program 75.4%

    \[\sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|} \]
  2. Step-by-step derivation
    1. sqr-neg75.4%

      \[\leadsto \sqrt{\left|\frac{a \cdot a - \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{a \cdot a}\right|} \]
    2. associate-/r*75.2%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{\frac{a \cdot a - \left(-b\right) \cdot \left(-b\right)}{a}}{a}}\right|} \]
    3. sqr-neg75.2%

      \[\leadsto \sqrt{\left|\frac{\frac{a \cdot a - \color{blue}{b \cdot b}}{a}}{a}\right|} \]
    4. associate-/r*75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a - b \cdot b}{a \cdot a}}\right|} \]
    5. div-sub75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a}{a \cdot a} - \frac{b \cdot b}{a \cdot a}}\right|} \]
    6. fabs-sub75.4%

      \[\leadsto \sqrt{\color{blue}{\left|\frac{b \cdot b}{a \cdot a} - \frac{a \cdot a}{a \cdot a}\right|}} \]
    7. times-frac75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{b}{a} \cdot \frac{b}{a}} - \frac{a \cdot a}{a \cdot a}\right|} \]
    8. *-inverses100.0%

      \[\leadsto \sqrt{\left|\frac{b}{a} \cdot \frac{b}{a} - \color{blue}{1}\right|} \]
  3. Simplified100.0%

    \[\leadsto \color{blue}{\sqrt{\left|\frac{b}{a} \cdot \frac{b}{a} - 1\right|}} \]
  4. Step-by-step derivation
    1. fabs-sub100.0%

      \[\leadsto \sqrt{\color{blue}{\left|1 - \frac{b}{a} \cdot \frac{b}{a}\right|}} \]
    2. *-inverses75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a}{a \cdot a}} - \frac{b}{a} \cdot \frac{b}{a}\right|} \]
    3. frac-times75.4%

      \[\leadsto \sqrt{\left|\frac{a \cdot a}{a \cdot a} - \color{blue}{\frac{b \cdot b}{a \cdot a}}\right|} \]
    4. div-sub75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a - b \cdot b}{a \cdot a}}\right|} \]
    5. add-sqr-sqrt75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}} \cdot \sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}}}\right|} \]
    6. fabs-sqr75.4%

      \[\leadsto \sqrt{\color{blue}{\sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}} \cdot \sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}}}} \]
    7. add-sqr-sqrt75.4%

      \[\leadsto \sqrt{\color{blue}{\frac{a \cdot a - b \cdot b}{a \cdot a}}} \]
    8. associate-/r*75.2%

      \[\leadsto \sqrt{\color{blue}{\frac{\frac{a \cdot a - b \cdot b}{a}}{a}}} \]
    9. sqrt-div75.2%

      \[\leadsto \color{blue}{\frac{\sqrt{\frac{a \cdot a - b \cdot b}{a}}}{\sqrt{a}}} \]
  5. Applied egg-rr75.2%

    \[\leadsto \color{blue}{\frac{\sqrt{\frac{a \cdot a - b \cdot b}{a}}}{\sqrt{a}}} \]
  6. Step-by-step derivation
    1. div-sub75.2%

      \[\leadsto \frac{\sqrt{\color{blue}{\frac{a \cdot a}{a} - \frac{b \cdot b}{a}}}}{\sqrt{a}} \]
    2. associate-/l*99.0%

      \[\leadsto \frac{\sqrt{\color{blue}{\frac{a}{\frac{a}{a}}} - \frac{b \cdot b}{a}}}{\sqrt{a}} \]
    3. *-inverses99.0%

      \[\leadsto \frac{\sqrt{\frac{a}{\color{blue}{1}} - \frac{b \cdot b}{a}}}{\sqrt{a}} \]
    4. /-rgt-identity99.0%

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

      \[\leadsto \frac{\sqrt{a - \color{blue}{b \cdot \frac{b}{a}}}}{\sqrt{a}} \]
  7. Simplified100.0%

    \[\leadsto \color{blue}{\frac{\sqrt{a - b \cdot \frac{b}{a}}}{\sqrt{a}}} \]
  8. Final simplification100.0%

    \[\leadsto \frac{\sqrt{a - b \cdot \frac{b}{a}}}{\sqrt{a}} \]

Alternative 2: 100.0% accurate, 1.9× speedup?

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

\\
\sqrt{1 - \frac{\frac{b}{a}}{\frac{a}{b}}}
\end{array}
Derivation
  1. Initial program 75.4%

    \[\sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|} \]
  2. Step-by-step derivation
    1. sqr-neg75.4%

      \[\leadsto \sqrt{\left|\frac{a \cdot a - \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{a \cdot a}\right|} \]
    2. associate-/r*75.2%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{\frac{a \cdot a - \left(-b\right) \cdot \left(-b\right)}{a}}{a}}\right|} \]
    3. sqr-neg75.2%

      \[\leadsto \sqrt{\left|\frac{\frac{a \cdot a - \color{blue}{b \cdot b}}{a}}{a}\right|} \]
    4. associate-/r*75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a - b \cdot b}{a \cdot a}}\right|} \]
    5. div-sub75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a}{a \cdot a} - \frac{b \cdot b}{a \cdot a}}\right|} \]
    6. fabs-sub75.4%

      \[\leadsto \sqrt{\color{blue}{\left|\frac{b \cdot b}{a \cdot a} - \frac{a \cdot a}{a \cdot a}\right|}} \]
    7. times-frac75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{b}{a} \cdot \frac{b}{a}} - \frac{a \cdot a}{a \cdot a}\right|} \]
    8. *-inverses100.0%

      \[\leadsto \sqrt{\left|\frac{b}{a} \cdot \frac{b}{a} - \color{blue}{1}\right|} \]
  3. Simplified100.0%

    \[\leadsto \color{blue}{\sqrt{\left|\frac{b}{a} \cdot \frac{b}{a} - 1\right|}} \]
  4. Step-by-step derivation
    1. fabs-sub100.0%

      \[\leadsto \sqrt{\color{blue}{\left|1 - \frac{b}{a} \cdot \frac{b}{a}\right|}} \]
    2. *-inverses75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a}{a \cdot a}} - \frac{b}{a} \cdot \frac{b}{a}\right|} \]
    3. frac-times75.4%

      \[\leadsto \sqrt{\left|\frac{a \cdot a}{a \cdot a} - \color{blue}{\frac{b \cdot b}{a \cdot a}}\right|} \]
    4. div-sub75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a - b \cdot b}{a \cdot a}}\right|} \]
    5. add-sqr-sqrt75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}} \cdot \sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}}}\right|} \]
    6. fabs-sqr75.4%

      \[\leadsto \sqrt{\color{blue}{\sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}} \cdot \sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}}}} \]
    7. add-sqr-sqrt75.4%

      \[\leadsto \sqrt{\color{blue}{\frac{a \cdot a - b \cdot b}{a \cdot a}}} \]
    8. associate-/r*75.2%

      \[\leadsto \sqrt{\color{blue}{\frac{\frac{a \cdot a - b \cdot b}{a}}{a}}} \]
    9. sqrt-div75.2%

      \[\leadsto \color{blue}{\frac{\sqrt{\frac{a \cdot a - b \cdot b}{a}}}{\sqrt{a}}} \]
  5. Applied egg-rr75.2%

    \[\leadsto \color{blue}{\frac{\sqrt{\frac{a \cdot a - b \cdot b}{a}}}{\sqrt{a}}} \]
  6. Step-by-step derivation
    1. div-sub75.2%

      \[\leadsto \frac{\sqrt{\color{blue}{\frac{a \cdot a}{a} - \frac{b \cdot b}{a}}}}{\sqrt{a}} \]
    2. associate-/l*99.0%

      \[\leadsto \frac{\sqrt{\color{blue}{\frac{a}{\frac{a}{a}}} - \frac{b \cdot b}{a}}}{\sqrt{a}} \]
    3. *-inverses99.0%

      \[\leadsto \frac{\sqrt{\frac{a}{\color{blue}{1}} - \frac{b \cdot b}{a}}}{\sqrt{a}} \]
    4. /-rgt-identity99.0%

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

      \[\leadsto \frac{\sqrt{a - \color{blue}{b \cdot \frac{b}{a}}}}{\sqrt{a}} \]
  7. Simplified100.0%

    \[\leadsto \color{blue}{\frac{\sqrt{a - b \cdot \frac{b}{a}}}{\sqrt{a}}} \]
  8. Step-by-step derivation
    1. add-log-exp100.0%

      \[\leadsto \color{blue}{\log \left(e^{\frac{\sqrt{a - b \cdot \frac{b}{a}}}{\sqrt{a}}}\right)} \]
    2. *-un-lft-identity100.0%

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

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

      \[\leadsto \color{blue}{0} + \log \left(e^{\frac{\sqrt{a - b \cdot \frac{b}{a}}}{\sqrt{a}}}\right) \]
    5. add-log-exp100.0%

      \[\leadsto 0 + \color{blue}{\frac{\sqrt{a - b \cdot \frac{b}{a}}}{\sqrt{a}}} \]
    6. sqrt-undiv100.0%

      \[\leadsto 0 + \color{blue}{\sqrt{\frac{a - b \cdot \frac{b}{a}}{a}}} \]
    7. div-sub100.0%

      \[\leadsto 0 + \sqrt{\color{blue}{\frac{a}{a} - \frac{b \cdot \frac{b}{a}}{a}}} \]
    8. associate-*l/100.0%

      \[\leadsto 0 + \sqrt{\frac{a}{a} - \color{blue}{\frac{b}{a} \cdot \frac{b}{a}}} \]
    9. pow2100.0%

      \[\leadsto 0 + \sqrt{\frac{a}{a} - \color{blue}{{\left(\frac{b}{a}\right)}^{2}}} \]
  9. Applied egg-rr100.0%

    \[\leadsto \color{blue}{0 + \sqrt{\frac{a}{a} - {\left(\frac{b}{a}\right)}^{2}}} \]
  10. Step-by-step derivation
    1. +-lft-identity100.0%

      \[\leadsto \color{blue}{\sqrt{\frac{a}{a} - {\left(\frac{b}{a}\right)}^{2}}} \]
    2. *-inverses100.0%

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

    \[\leadsto \color{blue}{\sqrt{1 - {\left(\frac{b}{a}\right)}^{2}}} \]
  12. Step-by-step derivation
    1. unpow299.3%

      \[\leadsto 1 + -0.5 \cdot \color{blue}{\left(\frac{b}{a} \cdot \frac{b}{a}\right)} \]
    2. clear-num99.3%

      \[\leadsto 1 + -0.5 \cdot \left(\frac{b}{a} \cdot \color{blue}{\frac{1}{\frac{a}{b}}}\right) \]
    3. un-div-inv99.3%

      \[\leadsto 1 + -0.5 \cdot \color{blue}{\frac{\frac{b}{a}}{\frac{a}{b}}} \]
  13. Applied egg-rr100.0%

    \[\leadsto \sqrt{1 - \color{blue}{\frac{\frac{b}{a}}{\frac{a}{b}}}} \]
  14. Final simplification100.0%

    \[\leadsto \sqrt{1 - \frac{\frac{b}{a}}{\frac{a}{b}}} \]

Alternative 3: 99.1% accurate, 19.2× speedup?

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

\\
1 + \frac{\frac{b}{a}}{\frac{a}{b}} \cdot -0.5
\end{array}
Derivation
  1. Initial program 75.4%

    \[\sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|} \]
  2. Step-by-step derivation
    1. sqr-neg75.4%

      \[\leadsto \sqrt{\left|\frac{a \cdot a - \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{a \cdot a}\right|} \]
    2. associate-/r*75.2%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{\frac{a \cdot a - \left(-b\right) \cdot \left(-b\right)}{a}}{a}}\right|} \]
    3. sqr-neg75.2%

      \[\leadsto \sqrt{\left|\frac{\frac{a \cdot a - \color{blue}{b \cdot b}}{a}}{a}\right|} \]
    4. associate-/r*75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a - b \cdot b}{a \cdot a}}\right|} \]
    5. div-sub75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a}{a \cdot a} - \frac{b \cdot b}{a \cdot a}}\right|} \]
    6. fabs-sub75.4%

      \[\leadsto \sqrt{\color{blue}{\left|\frac{b \cdot b}{a \cdot a} - \frac{a \cdot a}{a \cdot a}\right|}} \]
    7. times-frac75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{b}{a} \cdot \frac{b}{a}} - \frac{a \cdot a}{a \cdot a}\right|} \]
    8. *-inverses100.0%

      \[\leadsto \sqrt{\left|\frac{b}{a} \cdot \frac{b}{a} - \color{blue}{1}\right|} \]
  3. Simplified100.0%

    \[\leadsto \color{blue}{\sqrt{\left|\frac{b}{a} \cdot \frac{b}{a} - 1\right|}} \]
  4. Step-by-step derivation
    1. fabs-sub100.0%

      \[\leadsto \sqrt{\color{blue}{\left|1 - \frac{b}{a} \cdot \frac{b}{a}\right|}} \]
    2. *-inverses75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a}{a \cdot a}} - \frac{b}{a} \cdot \frac{b}{a}\right|} \]
    3. frac-times75.4%

      \[\leadsto \sqrt{\left|\frac{a \cdot a}{a \cdot a} - \color{blue}{\frac{b \cdot b}{a \cdot a}}\right|} \]
    4. div-sub75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a - b \cdot b}{a \cdot a}}\right|} \]
    5. add-sqr-sqrt75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}} \cdot \sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}}}\right|} \]
    6. fabs-sqr75.4%

      \[\leadsto \sqrt{\color{blue}{\sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}} \cdot \sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}}}} \]
    7. add-sqr-sqrt75.4%

      \[\leadsto \sqrt{\color{blue}{\frac{a \cdot a - b \cdot b}{a \cdot a}}} \]
    8. associate-/r*75.2%

      \[\leadsto \sqrt{\color{blue}{\frac{\frac{a \cdot a - b \cdot b}{a}}{a}}} \]
    9. sqrt-div75.2%

      \[\leadsto \color{blue}{\frac{\sqrt{\frac{a \cdot a - b \cdot b}{a}}}{\sqrt{a}}} \]
  5. Applied egg-rr75.2%

    \[\leadsto \color{blue}{\frac{\sqrt{\frac{a \cdot a - b \cdot b}{a}}}{\sqrt{a}}} \]
  6. Step-by-step derivation
    1. div-sub75.2%

      \[\leadsto \frac{\sqrt{\color{blue}{\frac{a \cdot a}{a} - \frac{b \cdot b}{a}}}}{\sqrt{a}} \]
    2. associate-/l*99.0%

      \[\leadsto \frac{\sqrt{\color{blue}{\frac{a}{\frac{a}{a}}} - \frac{b \cdot b}{a}}}{\sqrt{a}} \]
    3. *-inverses99.0%

      \[\leadsto \frac{\sqrt{\frac{a}{\color{blue}{1}} - \frac{b \cdot b}{a}}}{\sqrt{a}} \]
    4. /-rgt-identity99.0%

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

      \[\leadsto \frac{\sqrt{a - \color{blue}{b \cdot \frac{b}{a}}}}{\sqrt{a}} \]
  7. Simplified100.0%

    \[\leadsto \color{blue}{\frac{\sqrt{a - b \cdot \frac{b}{a}}}{\sqrt{a}}} \]
  8. Step-by-step derivation
    1. add-log-exp100.0%

      \[\leadsto \color{blue}{\log \left(e^{\frac{\sqrt{a - b \cdot \frac{b}{a}}}{\sqrt{a}}}\right)} \]
    2. *-un-lft-identity100.0%

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

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

      \[\leadsto \color{blue}{0} + \log \left(e^{\frac{\sqrt{a - b \cdot \frac{b}{a}}}{\sqrt{a}}}\right) \]
    5. add-log-exp100.0%

      \[\leadsto 0 + \color{blue}{\frac{\sqrt{a - b \cdot \frac{b}{a}}}{\sqrt{a}}} \]
    6. sqrt-undiv100.0%

      \[\leadsto 0 + \color{blue}{\sqrt{\frac{a - b \cdot \frac{b}{a}}{a}}} \]
    7. div-sub100.0%

      \[\leadsto 0 + \sqrt{\color{blue}{\frac{a}{a} - \frac{b \cdot \frac{b}{a}}{a}}} \]
    8. associate-*l/100.0%

      \[\leadsto 0 + \sqrt{\frac{a}{a} - \color{blue}{\frac{b}{a} \cdot \frac{b}{a}}} \]
    9. pow2100.0%

      \[\leadsto 0 + \sqrt{\frac{a}{a} - \color{blue}{{\left(\frac{b}{a}\right)}^{2}}} \]
  9. Applied egg-rr100.0%

    \[\leadsto \color{blue}{0 + \sqrt{\frac{a}{a} - {\left(\frac{b}{a}\right)}^{2}}} \]
  10. Step-by-step derivation
    1. +-lft-identity100.0%

      \[\leadsto \color{blue}{\sqrt{\frac{a}{a} - {\left(\frac{b}{a}\right)}^{2}}} \]
    2. *-inverses100.0%

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

    \[\leadsto \color{blue}{\sqrt{1 - {\left(\frac{b}{a}\right)}^{2}}} \]
  12. Taylor expanded in b around 0 75.0%

    \[\leadsto \color{blue}{1 + -0.5 \cdot \frac{{b}^{2}}{{a}^{2}}} \]
  13. Step-by-step derivation
    1. unpow275.0%

      \[\leadsto 1 + -0.5 \cdot \frac{\color{blue}{b \cdot b}}{{a}^{2}} \]
    2. unpow275.0%

      \[\leadsto 1 + -0.5 \cdot \frac{b \cdot b}{\color{blue}{a \cdot a}} \]
    3. times-frac99.3%

      \[\leadsto 1 + -0.5 \cdot \color{blue}{\left(\frac{b}{a} \cdot \frac{b}{a}\right)} \]
    4. unpow299.3%

      \[\leadsto 1 + -0.5 \cdot \color{blue}{{\left(\frac{b}{a}\right)}^{2}} \]
  14. Simplified99.3%

    \[\leadsto \color{blue}{1 + -0.5 \cdot {\left(\frac{b}{a}\right)}^{2}} \]
  15. Step-by-step derivation
    1. unpow299.3%

      \[\leadsto 1 + -0.5 \cdot \color{blue}{\left(\frac{b}{a} \cdot \frac{b}{a}\right)} \]
    2. clear-num99.3%

      \[\leadsto 1 + -0.5 \cdot \left(\frac{b}{a} \cdot \color{blue}{\frac{1}{\frac{a}{b}}}\right) \]
    3. un-div-inv99.3%

      \[\leadsto 1 + -0.5 \cdot \color{blue}{\frac{\frac{b}{a}}{\frac{a}{b}}} \]
  16. Applied egg-rr99.3%

    \[\leadsto 1 + -0.5 \cdot \color{blue}{\frac{\frac{b}{a}}{\frac{a}{b}}} \]
  17. Final simplification99.3%

    \[\leadsto 1 + \frac{\frac{b}{a}}{\frac{a}{b}} \cdot -0.5 \]

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 75.4%

    \[\sqrt{\left|\frac{a \cdot a - b \cdot b}{a \cdot a}\right|} \]
  2. Step-by-step derivation
    1. sqr-neg75.4%

      \[\leadsto \sqrt{\left|\frac{a \cdot a - \color{blue}{\left(-b\right) \cdot \left(-b\right)}}{a \cdot a}\right|} \]
    2. associate-/r*75.2%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{\frac{a \cdot a - \left(-b\right) \cdot \left(-b\right)}{a}}{a}}\right|} \]
    3. sqr-neg75.2%

      \[\leadsto \sqrt{\left|\frac{\frac{a \cdot a - \color{blue}{b \cdot b}}{a}}{a}\right|} \]
    4. associate-/r*75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a - b \cdot b}{a \cdot a}}\right|} \]
    5. div-sub75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a}{a \cdot a} - \frac{b \cdot b}{a \cdot a}}\right|} \]
    6. fabs-sub75.4%

      \[\leadsto \sqrt{\color{blue}{\left|\frac{b \cdot b}{a \cdot a} - \frac{a \cdot a}{a \cdot a}\right|}} \]
    7. times-frac75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{b}{a} \cdot \frac{b}{a}} - \frac{a \cdot a}{a \cdot a}\right|} \]
    8. *-inverses100.0%

      \[\leadsto \sqrt{\left|\frac{b}{a} \cdot \frac{b}{a} - \color{blue}{1}\right|} \]
  3. Simplified100.0%

    \[\leadsto \color{blue}{\sqrt{\left|\frac{b}{a} \cdot \frac{b}{a} - 1\right|}} \]
  4. Step-by-step derivation
    1. fabs-sub100.0%

      \[\leadsto \sqrt{\color{blue}{\left|1 - \frac{b}{a} \cdot \frac{b}{a}\right|}} \]
    2. *-inverses75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a}{a \cdot a}} - \frac{b}{a} \cdot \frac{b}{a}\right|} \]
    3. frac-times75.4%

      \[\leadsto \sqrt{\left|\frac{a \cdot a}{a \cdot a} - \color{blue}{\frac{b \cdot b}{a \cdot a}}\right|} \]
    4. div-sub75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\frac{a \cdot a - b \cdot b}{a \cdot a}}\right|} \]
    5. add-sqr-sqrt75.4%

      \[\leadsto \sqrt{\left|\color{blue}{\sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}} \cdot \sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}}}\right|} \]
    6. fabs-sqr75.4%

      \[\leadsto \sqrt{\color{blue}{\sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}} \cdot \sqrt{\frac{a \cdot a - b \cdot b}{a \cdot a}}}} \]
    7. add-sqr-sqrt75.4%

      \[\leadsto \sqrt{\color{blue}{\frac{a \cdot a - b \cdot b}{a \cdot a}}} \]
    8. associate-/r*75.2%

      \[\leadsto \sqrt{\color{blue}{\frac{\frac{a \cdot a - b \cdot b}{a}}{a}}} \]
    9. sqrt-div75.2%

      \[\leadsto \color{blue}{\frac{\sqrt{\frac{a \cdot a - b \cdot b}{a}}}{\sqrt{a}}} \]
  5. Applied egg-rr75.2%

    \[\leadsto \color{blue}{\frac{\sqrt{\frac{a \cdot a - b \cdot b}{a}}}{\sqrt{a}}} \]
  6. Step-by-step derivation
    1. div-sub75.2%

      \[\leadsto \frac{\sqrt{\color{blue}{\frac{a \cdot a}{a} - \frac{b \cdot b}{a}}}}{\sqrt{a}} \]
    2. associate-/l*99.0%

      \[\leadsto \frac{\sqrt{\color{blue}{\frac{a}{\frac{a}{a}}} - \frac{b \cdot b}{a}}}{\sqrt{a}} \]
    3. *-inverses99.0%

      \[\leadsto \frac{\sqrt{\frac{a}{\color{blue}{1}} - \frac{b \cdot b}{a}}}{\sqrt{a}} \]
    4. /-rgt-identity99.0%

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

      \[\leadsto \frac{\sqrt{a - \color{blue}{b \cdot \frac{b}{a}}}}{\sqrt{a}} \]
  7. Simplified100.0%

    \[\leadsto \color{blue}{\frac{\sqrt{a - b \cdot \frac{b}{a}}}{\sqrt{a}}} \]
  8. Taylor expanded in a around inf 98.2%

    \[\leadsto \color{blue}{1} \]
  9. Final simplification98.2%

    \[\leadsto 1 \]

Reproduce

?
herbie shell --seed 2023283 
(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)))))