3frac (problem 3.3.3)

Percentage Accurate: 69.3% → 99.5%
Time: 8.7s
Alternatives: 6
Speedup: 1.4×

Specification

?
\[\left|x\right| > 1\]
\[\begin{array}{l} \\ \left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1} \end{array} \]
(FPCore (x)
 :precision binary64
 (+ (- (/ 1.0 (+ x 1.0)) (/ 2.0 x)) (/ 1.0 (- x 1.0))))
double code(double x) {
	return ((1.0 / (x + 1.0)) - (2.0 / x)) + (1.0 / (x - 1.0));
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = ((1.0d0 / (x + 1.0d0)) - (2.0d0 / x)) + (1.0d0 / (x - 1.0d0))
end function
public static double code(double x) {
	return ((1.0 / (x + 1.0)) - (2.0 / x)) + (1.0 / (x - 1.0));
}
def code(x):
	return ((1.0 / (x + 1.0)) - (2.0 / x)) + (1.0 / (x - 1.0))
function code(x)
	return Float64(Float64(Float64(1.0 / Float64(x + 1.0)) - Float64(2.0 / x)) + Float64(1.0 / Float64(x - 1.0)))
end
function tmp = code(x)
	tmp = ((1.0 / (x + 1.0)) - (2.0 / x)) + (1.0 / (x - 1.0));
end
code[x_] := N[(N[(N[(1.0 / N[(x + 1.0), $MachinePrecision]), $MachinePrecision] - N[(2.0 / x), $MachinePrecision]), $MachinePrecision] + N[(1.0 / N[(x - 1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}
\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 6 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: 69.3% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1} \end{array} \]
(FPCore (x)
 :precision binary64
 (+ (- (/ 1.0 (+ x 1.0)) (/ 2.0 x)) (/ 1.0 (- x 1.0))))
double code(double x) {
	return ((1.0 / (x + 1.0)) - (2.0 / x)) + (1.0 / (x - 1.0));
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = ((1.0d0 / (x + 1.0d0)) - (2.0d0 / x)) + (1.0d0 / (x - 1.0d0))
end function
public static double code(double x) {
	return ((1.0 / (x + 1.0)) - (2.0 / x)) + (1.0 / (x - 1.0));
}
def code(x):
	return ((1.0 / (x + 1.0)) - (2.0 / x)) + (1.0 / (x - 1.0))
function code(x)
	return Float64(Float64(Float64(1.0 / Float64(x + 1.0)) - Float64(2.0 / x)) + Float64(1.0 / Float64(x - 1.0)))
end
function tmp = code(x)
	tmp = ((1.0 / (x + 1.0)) - (2.0 / x)) + (1.0 / (x - 1.0));
end
code[x_] := N[(N[(N[(1.0 / N[(x + 1.0), $MachinePrecision]), $MachinePrecision] - N[(2.0 / x), $MachinePrecision]), $MachinePrecision] + N[(1.0 / N[(x - 1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}
\end{array}

Alternative 1: 99.5% accurate, 0.1× speedup?

\[\begin{array}{l} \\ 2 \cdot \left({x}^{-5} + {x}^{-3}\right) \end{array} \]
(FPCore (x) :precision binary64 (* 2.0 (+ (pow x -5.0) (pow x -3.0))))
double code(double x) {
	return 2.0 * (pow(x, -5.0) + pow(x, -3.0));
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = 2.0d0 * ((x ** (-5.0d0)) + (x ** (-3.0d0)))
end function
public static double code(double x) {
	return 2.0 * (Math.pow(x, -5.0) + Math.pow(x, -3.0));
}
def code(x):
	return 2.0 * (math.pow(x, -5.0) + math.pow(x, -3.0))
function code(x)
	return Float64(2.0 * Float64((x ^ -5.0) + (x ^ -3.0)))
end
function tmp = code(x)
	tmp = 2.0 * ((x ^ -5.0) + (x ^ -3.0));
end
code[x_] := N[(2.0 * N[(N[Power[x, -5.0], $MachinePrecision] + N[Power[x, -3.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
2 \cdot \left({x}^{-5} + {x}^{-3}\right)
\end{array}
Derivation
  1. Initial program 72.7%

    \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1} \]
  2. Step-by-step derivation
    1. associate-+l-72.7%

      \[\leadsto \color{blue}{\frac{1}{x + 1} - \left(\frac{2}{x} - \frac{1}{x - 1}\right)} \]
    2. sub-neg72.7%

      \[\leadsto \color{blue}{\frac{1}{x + 1} + \left(-\left(\frac{2}{x} - \frac{1}{x - 1}\right)\right)} \]
    3. +-commutative72.7%

      \[\leadsto \frac{1}{\color{blue}{1 + x}} + \left(-\left(\frac{2}{x} - \frac{1}{x - 1}\right)\right) \]
    4. neg-sub072.7%

      \[\leadsto \frac{1}{1 + x} + \color{blue}{\left(0 - \left(\frac{2}{x} - \frac{1}{x - 1}\right)\right)} \]
    5. associate-+l-72.7%

      \[\leadsto \frac{1}{1 + x} + \color{blue}{\left(\left(0 - \frac{2}{x}\right) + \frac{1}{x - 1}\right)} \]
    6. neg-sub072.7%

      \[\leadsto \frac{1}{1 + x} + \left(\color{blue}{\left(-\frac{2}{x}\right)} + \frac{1}{x - 1}\right) \]
    7. distribute-neg-frac72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\color{blue}{\frac{-2}{x}} + \frac{1}{x - 1}\right) \]
    8. metadata-eval72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{\color{blue}{-2}}{x} + \frac{1}{x - 1}\right) \]
    9. sub-neg72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{\color{blue}{x + \left(-1\right)}}\right) \]
    10. metadata-eval72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{x + \color{blue}{-1}}\right) \]
  3. Simplified72.7%

    \[\leadsto \color{blue}{\frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right)} \]
  4. Add Preprocessing
  5. Taylor expanded in x around inf 99.2%

    \[\leadsto \color{blue}{2 \cdot \frac{1}{{x}^{3}} + 2 \cdot \frac{1}{{x}^{5}}} \]
  6. Step-by-step derivation
    1. associate-*r/99.2%

      \[\leadsto \color{blue}{\frac{2 \cdot 1}{{x}^{3}}} + 2 \cdot \frac{1}{{x}^{5}} \]
    2. metadata-eval99.2%

      \[\leadsto \frac{\color{blue}{2}}{{x}^{3}} + 2 \cdot \frac{1}{{x}^{5}} \]
    3. associate-*r/99.2%

      \[\leadsto \frac{2}{{x}^{3}} + \color{blue}{\frac{2 \cdot 1}{{x}^{5}}} \]
    4. metadata-eval99.2%

      \[\leadsto \frac{2}{{x}^{3}} + \frac{\color{blue}{2}}{{x}^{5}} \]
  7. Simplified99.2%

    \[\leadsto \color{blue}{\frac{2}{{x}^{3}} + \frac{2}{{x}^{5}}} \]
  8. Step-by-step derivation
    1. expm1-log1p-u99.2%

      \[\leadsto \color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\frac{2}{{x}^{3}} + \frac{2}{{x}^{5}}\right)\right)} \]
    2. expm1-udef71.5%

      \[\leadsto \color{blue}{e^{\mathsf{log1p}\left(\frac{2}{{x}^{3}} + \frac{2}{{x}^{5}}\right)} - 1} \]
    3. div-inv71.5%

      \[\leadsto e^{\mathsf{log1p}\left(\color{blue}{2 \cdot \frac{1}{{x}^{3}}} + \frac{2}{{x}^{5}}\right)} - 1 \]
    4. fma-def71.5%

      \[\leadsto e^{\mathsf{log1p}\left(\color{blue}{\mathsf{fma}\left(2, \frac{1}{{x}^{3}}, \frac{2}{{x}^{5}}\right)}\right)} - 1 \]
    5. pow-flip71.5%

      \[\leadsto e^{\mathsf{log1p}\left(\mathsf{fma}\left(2, \color{blue}{{x}^{\left(-3\right)}}, \frac{2}{{x}^{5}}\right)\right)} - 1 \]
    6. metadata-eval71.5%

      \[\leadsto e^{\mathsf{log1p}\left(\mathsf{fma}\left(2, {x}^{\color{blue}{-3}}, \frac{2}{{x}^{5}}\right)\right)} - 1 \]
    7. div-inv71.5%

      \[\leadsto e^{\mathsf{log1p}\left(\mathsf{fma}\left(2, {x}^{-3}, \color{blue}{2 \cdot \frac{1}{{x}^{5}}}\right)\right)} - 1 \]
    8. pow-flip71.5%

      \[\leadsto e^{\mathsf{log1p}\left(\mathsf{fma}\left(2, {x}^{-3}, 2 \cdot \color{blue}{{x}^{\left(-5\right)}}\right)\right)} - 1 \]
    9. metadata-eval71.5%

      \[\leadsto e^{\mathsf{log1p}\left(\mathsf{fma}\left(2, {x}^{-3}, 2 \cdot {x}^{\color{blue}{-5}}\right)\right)} - 1 \]
  9. Applied egg-rr71.5%

    \[\leadsto \color{blue}{e^{\mathsf{log1p}\left(\mathsf{fma}\left(2, {x}^{-3}, 2 \cdot {x}^{-5}\right)\right)} - 1} \]
  10. Step-by-step derivation
    1. expm1-def99.7%

      \[\leadsto \color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\mathsf{fma}\left(2, {x}^{-3}, 2 \cdot {x}^{-5}\right)\right)\right)} \]
    2. expm1-log1p99.7%

      \[\leadsto \color{blue}{\mathsf{fma}\left(2, {x}^{-3}, 2 \cdot {x}^{-5}\right)} \]
    3. fma-udef99.7%

      \[\leadsto \color{blue}{2 \cdot {x}^{-3} + 2 \cdot {x}^{-5}} \]
    4. +-commutative99.7%

      \[\leadsto \color{blue}{2 \cdot {x}^{-5} + 2 \cdot {x}^{-3}} \]
    5. distribute-lft-out99.7%

      \[\leadsto \color{blue}{2 \cdot \left({x}^{-5} + {x}^{-3}\right)} \]
  11. Simplified99.7%

    \[\leadsto \color{blue}{2 \cdot \left({x}^{-5} + {x}^{-3}\right)} \]
  12. Final simplification99.7%

    \[\leadsto 2 \cdot \left({x}^{-5} + {x}^{-3}\right) \]
  13. Add Preprocessing

Alternative 2: 99.1% accurate, 1.4× speedup?

\[\begin{array}{l} \\ \frac{2}{\left(x \cdot \left(x + -1\right)\right) \cdot \left(x + 1\right)} \end{array} \]
(FPCore (x) :precision binary64 (/ 2.0 (* (* x (+ x -1.0)) (+ x 1.0))))
double code(double x) {
	return 2.0 / ((x * (x + -1.0)) * (x + 1.0));
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = 2.0d0 / ((x * (x + (-1.0d0))) * (x + 1.0d0))
end function
public static double code(double x) {
	return 2.0 / ((x * (x + -1.0)) * (x + 1.0));
}
def code(x):
	return 2.0 / ((x * (x + -1.0)) * (x + 1.0))
function code(x)
	return Float64(2.0 / Float64(Float64(x * Float64(x + -1.0)) * Float64(x + 1.0)))
end
function tmp = code(x)
	tmp = 2.0 / ((x * (x + -1.0)) * (x + 1.0));
end
code[x_] := N[(2.0 / N[(N[(x * N[(x + -1.0), $MachinePrecision]), $MachinePrecision] * N[(x + 1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{2}{\left(x \cdot \left(x + -1\right)\right) \cdot \left(x + 1\right)}
\end{array}
Derivation
  1. Initial program 72.7%

    \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1} \]
  2. Step-by-step derivation
    1. associate-+l-72.7%

      \[\leadsto \color{blue}{\frac{1}{x + 1} - \left(\frac{2}{x} - \frac{1}{x - 1}\right)} \]
    2. sub-neg72.7%

      \[\leadsto \color{blue}{\frac{1}{x + 1} + \left(-\left(\frac{2}{x} - \frac{1}{x - 1}\right)\right)} \]
    3. +-commutative72.7%

      \[\leadsto \frac{1}{\color{blue}{1 + x}} + \left(-\left(\frac{2}{x} - \frac{1}{x - 1}\right)\right) \]
    4. neg-sub072.7%

      \[\leadsto \frac{1}{1 + x} + \color{blue}{\left(0 - \left(\frac{2}{x} - \frac{1}{x - 1}\right)\right)} \]
    5. associate-+l-72.7%

      \[\leadsto \frac{1}{1 + x} + \color{blue}{\left(\left(0 - \frac{2}{x}\right) + \frac{1}{x - 1}\right)} \]
    6. neg-sub072.7%

      \[\leadsto \frac{1}{1 + x} + \left(\color{blue}{\left(-\frac{2}{x}\right)} + \frac{1}{x - 1}\right) \]
    7. distribute-neg-frac72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\color{blue}{\frac{-2}{x}} + \frac{1}{x - 1}\right) \]
    8. metadata-eval72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{\color{blue}{-2}}{x} + \frac{1}{x - 1}\right) \]
    9. sub-neg72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{\color{blue}{x + \left(-1\right)}}\right) \]
    10. metadata-eval72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{x + \color{blue}{-1}}\right) \]
  3. Simplified72.7%

    \[\leadsto \color{blue}{\frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right)} \]
  4. Add Preprocessing
  5. Step-by-step derivation
    1. flip-+21.1%

      \[\leadsto \frac{1}{\color{blue}{\frac{1 \cdot 1 - x \cdot x}{1 - x}}} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right) \]
    2. sub-neg21.1%

      \[\leadsto \frac{1}{\frac{1 \cdot 1 - x \cdot x}{\color{blue}{1 + \left(-x\right)}}} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right) \]
    3. metadata-eval21.1%

      \[\leadsto \frac{1}{\frac{1 \cdot 1 - x \cdot x}{\color{blue}{\left(--1\right)} + \left(-x\right)}} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right) \]
    4. distribute-neg-in21.1%

      \[\leadsto \frac{1}{\frac{1 \cdot 1 - x \cdot x}{\color{blue}{-\left(-1 + x\right)}}} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right) \]
    5. +-commutative21.1%

      \[\leadsto \frac{1}{\frac{1 \cdot 1 - x \cdot x}{-\color{blue}{\left(x + -1\right)}}} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right) \]
    6. associate-/r/18.1%

      \[\leadsto \color{blue}{\frac{1}{1 \cdot 1 - x \cdot x} \cdot \left(-\left(x + -1\right)\right)} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right) \]
    7. fma-def7.5%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\frac{1}{1 \cdot 1 - x \cdot x}, -\left(x + -1\right), \frac{-2}{x} + \frac{1}{x + -1}\right)} \]
    8. metadata-eval7.5%

      \[\leadsto \mathsf{fma}\left(\frac{1}{\color{blue}{1} - x \cdot x}, -\left(x + -1\right), \frac{-2}{x} + \frac{1}{x + -1}\right) \]
    9. pow27.5%

      \[\leadsto \mathsf{fma}\left(\frac{1}{1 - \color{blue}{{x}^{2}}}, -\left(x + -1\right), \frac{-2}{x} + \frac{1}{x + -1}\right) \]
    10. +-commutative7.5%

      \[\leadsto \mathsf{fma}\left(\frac{1}{1 - {x}^{2}}, -\color{blue}{\left(-1 + x\right)}, \frac{-2}{x} + \frac{1}{x + -1}\right) \]
    11. distribute-neg-in7.5%

      \[\leadsto \mathsf{fma}\left(\frac{1}{1 - {x}^{2}}, \color{blue}{\left(--1\right) + \left(-x\right)}, \frac{-2}{x} + \frac{1}{x + -1}\right) \]
    12. metadata-eval7.5%

      \[\leadsto \mathsf{fma}\left(\frac{1}{1 - {x}^{2}}, \color{blue}{1} + \left(-x\right), \frac{-2}{x} + \frac{1}{x + -1}\right) \]
    13. sub-neg7.5%

      \[\leadsto \mathsf{fma}\left(\frac{1}{1 - {x}^{2}}, \color{blue}{1 - x}, \frac{-2}{x} + \frac{1}{x + -1}\right) \]
  6. Applied egg-rr7.5%

    \[\leadsto \color{blue}{\mathsf{fma}\left(\frac{1}{1 - {x}^{2}}, 1 - x, \frac{-2}{x} + \frac{1}{x + -1}\right)} \]
  7. Step-by-step derivation
    1. fma-udef18.1%

      \[\leadsto \color{blue}{\frac{1}{1 - {x}^{2}} \cdot \left(1 - x\right) + \left(\frac{-2}{x} + \frac{1}{x + -1}\right)} \]
    2. associate-*l/18.8%

      \[\leadsto \color{blue}{\frac{1 \cdot \left(1 - x\right)}{1 - {x}^{2}}} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right) \]
    3. *-lft-identity18.8%

      \[\leadsto \frac{\color{blue}{1 - x}}{1 - {x}^{2}} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right) \]
  8. Simplified18.8%

    \[\leadsto \color{blue}{\frac{1 - x}{1 - {x}^{2}} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right)} \]
  9. Step-by-step derivation
    1. +-commutative18.8%

      \[\leadsto \color{blue}{\left(\frac{-2}{x} + \frac{1}{x + -1}\right) + \frac{1 - x}{1 - {x}^{2}}} \]
    2. frac-add72.7%

      \[\leadsto \color{blue}{\frac{-2 \cdot \left(x + -1\right) + x \cdot 1}{x \cdot \left(x + -1\right)}} + \frac{1 - x}{1 - {x}^{2}} \]
    3. clear-num70.4%

      \[\leadsto \frac{-2 \cdot \left(x + -1\right) + x \cdot 1}{x \cdot \left(x + -1\right)} + \color{blue}{\frac{1}{\frac{1 - {x}^{2}}{1 - x}}} \]
    4. metadata-eval70.4%

      \[\leadsto \frac{-2 \cdot \left(x + -1\right) + x \cdot 1}{x \cdot \left(x + -1\right)} + \frac{1}{\frac{\color{blue}{1 \cdot 1} - {x}^{2}}{1 - x}} \]
    5. unpow270.4%

      \[\leadsto \frac{-2 \cdot \left(x + -1\right) + x \cdot 1}{x \cdot \left(x + -1\right)} + \frac{1}{\frac{1 \cdot 1 - \color{blue}{x \cdot x}}{1 - x}} \]
    6. flip-+19.0%

      \[\leadsto \frac{-2 \cdot \left(x + -1\right) + x \cdot 1}{x \cdot \left(x + -1\right)} + \frac{1}{\color{blue}{1 + x}} \]
    7. frac-add19.5%

      \[\leadsto \color{blue}{\frac{\left(-2 \cdot \left(x + -1\right) + x \cdot 1\right) \cdot \left(1 + x\right) + \left(x \cdot \left(x + -1\right)\right) \cdot 1}{\left(x \cdot \left(x + -1\right)\right) \cdot \left(1 + x\right)}} \]
    8. fma-def19.5%

      \[\leadsto \frac{\color{blue}{\mathsf{fma}\left(-2, x + -1, x \cdot 1\right)} \cdot \left(1 + x\right) + \left(x \cdot \left(x + -1\right)\right) \cdot 1}{\left(x \cdot \left(x + -1\right)\right) \cdot \left(1 + x\right)} \]
    9. +-commutative19.5%

      \[\leadsto \frac{\mathsf{fma}\left(-2, x + -1, x \cdot 1\right) \cdot \color{blue}{\left(x + 1\right)} + \left(x \cdot \left(x + -1\right)\right) \cdot 1}{\left(x \cdot \left(x + -1\right)\right) \cdot \left(1 + x\right)} \]
    10. +-commutative19.5%

      \[\leadsto \frac{\mathsf{fma}\left(-2, x + -1, x \cdot 1\right) \cdot \left(x + 1\right) + \left(x \cdot \left(x + -1\right)\right) \cdot 1}{\left(x \cdot \left(x + -1\right)\right) \cdot \color{blue}{\left(x + 1\right)}} \]
  10. Applied egg-rr19.5%

    \[\leadsto \color{blue}{\frac{\mathsf{fma}\left(-2, x + -1, x \cdot 1\right) \cdot \left(x + 1\right) + \left(x \cdot \left(x + -1\right)\right) \cdot 1}{\left(x \cdot \left(x + -1\right)\right) \cdot \left(x + 1\right)}} \]
  11. Taylor expanded in x around 0 99.5%

    \[\leadsto \frac{\color{blue}{2}}{\left(x \cdot \left(x + -1\right)\right) \cdot \left(x + 1\right)} \]
  12. Final simplification99.5%

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

Alternative 3: 68.0% accurate, 1.7× speedup?

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

\\
\frac{1}{x + -1} + \frac{-1}{x}
\end{array}
Derivation
  1. Initial program 72.7%

    \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1} \]
  2. Step-by-step derivation
    1. associate-+l-72.7%

      \[\leadsto \color{blue}{\frac{1}{x + 1} - \left(\frac{2}{x} - \frac{1}{x - 1}\right)} \]
    2. sub-neg72.7%

      \[\leadsto \color{blue}{\frac{1}{x + 1} + \left(-\left(\frac{2}{x} - \frac{1}{x - 1}\right)\right)} \]
    3. +-commutative72.7%

      \[\leadsto \frac{1}{\color{blue}{1 + x}} + \left(-\left(\frac{2}{x} - \frac{1}{x - 1}\right)\right) \]
    4. neg-sub072.7%

      \[\leadsto \frac{1}{1 + x} + \color{blue}{\left(0 - \left(\frac{2}{x} - \frac{1}{x - 1}\right)\right)} \]
    5. associate-+l-72.7%

      \[\leadsto \frac{1}{1 + x} + \color{blue}{\left(\left(0 - \frac{2}{x}\right) + \frac{1}{x - 1}\right)} \]
    6. neg-sub072.7%

      \[\leadsto \frac{1}{1 + x} + \left(\color{blue}{\left(-\frac{2}{x}\right)} + \frac{1}{x - 1}\right) \]
    7. distribute-neg-frac72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\color{blue}{\frac{-2}{x}} + \frac{1}{x - 1}\right) \]
    8. metadata-eval72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{\color{blue}{-2}}{x} + \frac{1}{x - 1}\right) \]
    9. sub-neg72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{\color{blue}{x + \left(-1\right)}}\right) \]
    10. metadata-eval72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{x + \color{blue}{-1}}\right) \]
  3. Simplified72.7%

    \[\leadsto \color{blue}{\frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right)} \]
  4. Add Preprocessing
  5. Taylor expanded in x around inf 71.4%

    \[\leadsto \color{blue}{\frac{1}{x}} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right) \]
  6. Step-by-step derivation
    1. expm1-log1p-u71.4%

      \[\leadsto \color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\frac{1}{x} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right)\right)\right)} \]
    2. expm1-udef71.3%

      \[\leadsto \color{blue}{e^{\mathsf{log1p}\left(\frac{1}{x} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right)\right)} - 1} \]
  7. Applied egg-rr71.3%

    \[\leadsto \color{blue}{e^{\mathsf{log1p}\left(\frac{1}{x} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right)\right)} - 1} \]
  8. Step-by-step derivation
    1. expm1-def71.4%

      \[\leadsto \color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\frac{1}{x} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right)\right)\right)} \]
    2. expm1-log1p71.4%

      \[\leadsto \color{blue}{\frac{1}{x} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right)} \]
    3. associate-+r+71.4%

      \[\leadsto \color{blue}{\left(\frac{1}{x} + \frac{-2}{x}\right) + \frac{1}{x + -1}} \]
    4. +-commutative71.4%

      \[\leadsto \color{blue}{\left(\frac{-2}{x} + \frac{1}{x}\right)} + \frac{1}{x + -1} \]
    5. associate-+l+71.4%

      \[\leadsto \color{blue}{\frac{-2}{x} + \left(\frac{1}{x} + \frac{1}{x + -1}\right)} \]
  9. Simplified71.4%

    \[\leadsto \color{blue}{\frac{-2}{x} + \left(\frac{1}{x} + \frac{1}{x + -1}\right)} \]
  10. Step-by-step derivation
    1. expm1-log1p-u71.4%

      \[\leadsto \color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\frac{-2}{x} + \left(\frac{1}{x} + \frac{1}{x + -1}\right)\right)\right)} \]
    2. expm1-udef71.3%

      \[\leadsto \color{blue}{e^{\mathsf{log1p}\left(\frac{-2}{x} + \left(\frac{1}{x} + \frac{1}{x + -1}\right)\right)} - 1} \]
    3. associate-+r+71.3%

      \[\leadsto e^{\mathsf{log1p}\left(\color{blue}{\left(\frac{-2}{x} + \frac{1}{x}\right) + \frac{1}{x + -1}}\right)} - 1 \]
    4. +-commutative71.3%

      \[\leadsto e^{\mathsf{log1p}\left(\color{blue}{\frac{1}{x + -1} + \left(\frac{-2}{x} + \frac{1}{x}\right)}\right)} - 1 \]
    5. div-inv71.3%

      \[\leadsto e^{\mathsf{log1p}\left(\frac{1}{x + -1} + \left(\color{blue}{-2 \cdot \frac{1}{x}} + \frac{1}{x}\right)\right)} - 1 \]
    6. *-un-lft-identity71.3%

      \[\leadsto e^{\mathsf{log1p}\left(\frac{1}{x + -1} + \left(-2 \cdot \frac{1}{x} + \color{blue}{1 \cdot \frac{1}{x}}\right)\right)} - 1 \]
    7. distribute-rgt-out71.3%

      \[\leadsto e^{\mathsf{log1p}\left(\frac{1}{x + -1} + \color{blue}{\frac{1}{x} \cdot \left(-2 + 1\right)}\right)} - 1 \]
    8. metadata-eval71.3%

      \[\leadsto e^{\mathsf{log1p}\left(\frac{1}{x + -1} + \frac{1}{x} \cdot \color{blue}{-1}\right)} - 1 \]
  11. Applied egg-rr71.3%

    \[\leadsto \color{blue}{e^{\mathsf{log1p}\left(\frac{1}{x + -1} + \frac{1}{x} \cdot -1\right)} - 1} \]
  12. Step-by-step derivation
    1. expm1-def71.4%

      \[\leadsto \color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(\frac{1}{x + -1} + \frac{1}{x} \cdot -1\right)\right)} \]
    2. expm1-log1p71.4%

      \[\leadsto \color{blue}{\frac{1}{x + -1} + \frac{1}{x} \cdot -1} \]
    3. +-commutative71.4%

      \[\leadsto \frac{1}{\color{blue}{-1 + x}} + \frac{1}{x} \cdot -1 \]
    4. associate-*l/71.4%

      \[\leadsto \frac{1}{-1 + x} + \color{blue}{\frac{1 \cdot -1}{x}} \]
    5. metadata-eval71.4%

      \[\leadsto \frac{1}{-1 + x} + \frac{\color{blue}{-1}}{x} \]
  13. Simplified71.4%

    \[\leadsto \color{blue}{\frac{1}{-1 + x} + \frac{-1}{x}} \]
  14. Final simplification71.4%

    \[\leadsto \frac{1}{x + -1} + \frac{-1}{x} \]
  15. Add Preprocessing

Alternative 4: 67.7% accurate, 2.1× speedup?

\[\begin{array}{l} \\ 1 + \left(-1 + \frac{-2}{x}\right) \end{array} \]
(FPCore (x) :precision binary64 (+ 1.0 (+ -1.0 (/ -2.0 x))))
double code(double x) {
	return 1.0 + (-1.0 + (-2.0 / x));
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = 1.0d0 + ((-1.0d0) + ((-2.0d0) / x))
end function
public static double code(double x) {
	return 1.0 + (-1.0 + (-2.0 / x));
}
def code(x):
	return 1.0 + (-1.0 + (-2.0 / x))
function code(x)
	return Float64(1.0 + Float64(-1.0 + Float64(-2.0 / x)))
end
function tmp = code(x)
	tmp = 1.0 + (-1.0 + (-2.0 / x));
end
code[x_] := N[(1.0 + N[(-1.0 + N[(-2.0 / x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
1 + \left(-1 + \frac{-2}{x}\right)
\end{array}
Derivation
  1. Initial program 72.7%

    \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1} \]
  2. Step-by-step derivation
    1. associate-+l-72.7%

      \[\leadsto \color{blue}{\frac{1}{x + 1} - \left(\frac{2}{x} - \frac{1}{x - 1}\right)} \]
    2. sub-neg72.7%

      \[\leadsto \color{blue}{\frac{1}{x + 1} + \left(-\left(\frac{2}{x} - \frac{1}{x - 1}\right)\right)} \]
    3. +-commutative72.7%

      \[\leadsto \frac{1}{\color{blue}{1 + x}} + \left(-\left(\frac{2}{x} - \frac{1}{x - 1}\right)\right) \]
    4. neg-sub072.7%

      \[\leadsto \frac{1}{1 + x} + \color{blue}{\left(0 - \left(\frac{2}{x} - \frac{1}{x - 1}\right)\right)} \]
    5. associate-+l-72.7%

      \[\leadsto \frac{1}{1 + x} + \color{blue}{\left(\left(0 - \frac{2}{x}\right) + \frac{1}{x - 1}\right)} \]
    6. neg-sub072.7%

      \[\leadsto \frac{1}{1 + x} + \left(\color{blue}{\left(-\frac{2}{x}\right)} + \frac{1}{x - 1}\right) \]
    7. distribute-neg-frac72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\color{blue}{\frac{-2}{x}} + \frac{1}{x - 1}\right) \]
    8. metadata-eval72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{\color{blue}{-2}}{x} + \frac{1}{x - 1}\right) \]
    9. sub-neg72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{\color{blue}{x + \left(-1\right)}}\right) \]
    10. metadata-eval72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{x + \color{blue}{-1}}\right) \]
  3. Simplified72.7%

    \[\leadsto \color{blue}{\frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right)} \]
  4. Add Preprocessing
  5. Taylor expanded in x around 0 3.3%

    \[\leadsto \color{blue}{1} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right) \]
  6. Taylor expanded in x around 0 71.1%

    \[\leadsto 1 + \color{blue}{\left(-\left(1 + 2 \cdot \frac{1}{x}\right)\right)} \]
  7. Step-by-step derivation
    1. +-commutative71.1%

      \[\leadsto 1 + \left(-\color{blue}{\left(2 \cdot \frac{1}{x} + 1\right)}\right) \]
    2. distribute-neg-in71.1%

      \[\leadsto 1 + \color{blue}{\left(\left(-2 \cdot \frac{1}{x}\right) + \left(-1\right)\right)} \]
    3. associate-*r/71.1%

      \[\leadsto 1 + \left(\left(-\color{blue}{\frac{2 \cdot 1}{x}}\right) + \left(-1\right)\right) \]
    4. metadata-eval71.1%

      \[\leadsto 1 + \left(\left(-\frac{\color{blue}{2}}{x}\right) + \left(-1\right)\right) \]
    5. distribute-neg-frac71.1%

      \[\leadsto 1 + \left(\color{blue}{\frac{-2}{x}} + \left(-1\right)\right) \]
    6. metadata-eval71.1%

      \[\leadsto 1 + \left(\frac{\color{blue}{-2}}{x} + \left(-1\right)\right) \]
    7. metadata-eval71.1%

      \[\leadsto 1 + \left(\frac{-2}{x} + \color{blue}{-1}\right) \]
  8. Simplified71.1%

    \[\leadsto 1 + \color{blue}{\left(\frac{-2}{x} + -1\right)} \]
  9. Final simplification71.1%

    \[\leadsto 1 + \left(-1 + \frac{-2}{x}\right) \]
  10. Add Preprocessing

Alternative 5: 5.1% accurate, 5.0× speedup?

\[\begin{array}{l} \\ \frac{-2}{x} \end{array} \]
(FPCore (x) :precision binary64 (/ -2.0 x))
double code(double x) {
	return -2.0 / x;
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = (-2.0d0) / x
end function
public static double code(double x) {
	return -2.0 / x;
}
def code(x):
	return -2.0 / x
function code(x)
	return Float64(-2.0 / x)
end
function tmp = code(x)
	tmp = -2.0 / x;
end
code[x_] := N[(-2.0 / x), $MachinePrecision]
\begin{array}{l}

\\
\frac{-2}{x}
\end{array}
Derivation
  1. Initial program 72.7%

    \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1} \]
  2. Step-by-step derivation
    1. associate-+l-72.7%

      \[\leadsto \color{blue}{\frac{1}{x + 1} - \left(\frac{2}{x} - \frac{1}{x - 1}\right)} \]
    2. sub-neg72.7%

      \[\leadsto \color{blue}{\frac{1}{x + 1} + \left(-\left(\frac{2}{x} - \frac{1}{x - 1}\right)\right)} \]
    3. +-commutative72.7%

      \[\leadsto \frac{1}{\color{blue}{1 + x}} + \left(-\left(\frac{2}{x} - \frac{1}{x - 1}\right)\right) \]
    4. neg-sub072.7%

      \[\leadsto \frac{1}{1 + x} + \color{blue}{\left(0 - \left(\frac{2}{x} - \frac{1}{x - 1}\right)\right)} \]
    5. associate-+l-72.7%

      \[\leadsto \frac{1}{1 + x} + \color{blue}{\left(\left(0 - \frac{2}{x}\right) + \frac{1}{x - 1}\right)} \]
    6. neg-sub072.7%

      \[\leadsto \frac{1}{1 + x} + \left(\color{blue}{\left(-\frac{2}{x}\right)} + \frac{1}{x - 1}\right) \]
    7. distribute-neg-frac72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\color{blue}{\frac{-2}{x}} + \frac{1}{x - 1}\right) \]
    8. metadata-eval72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{\color{blue}{-2}}{x} + \frac{1}{x - 1}\right) \]
    9. sub-neg72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{\color{blue}{x + \left(-1\right)}}\right) \]
    10. metadata-eval72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{x + \color{blue}{-1}}\right) \]
  3. Simplified72.7%

    \[\leadsto \color{blue}{\frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right)} \]
  4. Add Preprocessing
  5. Taylor expanded in x around 0 5.4%

    \[\leadsto \color{blue}{\frac{-2}{x}} \]
  6. Final simplification5.4%

    \[\leadsto \frac{-2}{x} \]
  7. Add Preprocessing

Alternative 6: 5.1% accurate, 5.0× speedup?

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

\\
\frac{-1}{x}
\end{array}
Derivation
  1. Initial program 72.7%

    \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1} \]
  2. Step-by-step derivation
    1. associate-+l-72.7%

      \[\leadsto \color{blue}{\frac{1}{x + 1} - \left(\frac{2}{x} - \frac{1}{x - 1}\right)} \]
    2. sub-neg72.7%

      \[\leadsto \color{blue}{\frac{1}{x + 1} + \left(-\left(\frac{2}{x} - \frac{1}{x - 1}\right)\right)} \]
    3. +-commutative72.7%

      \[\leadsto \frac{1}{\color{blue}{1 + x}} + \left(-\left(\frac{2}{x} - \frac{1}{x - 1}\right)\right) \]
    4. neg-sub072.7%

      \[\leadsto \frac{1}{1 + x} + \color{blue}{\left(0 - \left(\frac{2}{x} - \frac{1}{x - 1}\right)\right)} \]
    5. associate-+l-72.7%

      \[\leadsto \frac{1}{1 + x} + \color{blue}{\left(\left(0 - \frac{2}{x}\right) + \frac{1}{x - 1}\right)} \]
    6. neg-sub072.7%

      \[\leadsto \frac{1}{1 + x} + \left(\color{blue}{\left(-\frac{2}{x}\right)} + \frac{1}{x - 1}\right) \]
    7. distribute-neg-frac72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\color{blue}{\frac{-2}{x}} + \frac{1}{x - 1}\right) \]
    8. metadata-eval72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{\color{blue}{-2}}{x} + \frac{1}{x - 1}\right) \]
    9. sub-neg72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{\color{blue}{x + \left(-1\right)}}\right) \]
    10. metadata-eval72.7%

      \[\leadsto \frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{x + \color{blue}{-1}}\right) \]
  3. Simplified72.7%

    \[\leadsto \color{blue}{\frac{1}{1 + x} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right)} \]
  4. Add Preprocessing
  5. Taylor expanded in x around inf 71.4%

    \[\leadsto \color{blue}{\frac{1}{x}} + \left(\frac{-2}{x} + \frac{1}{x + -1}\right) \]
  6. Taylor expanded in x around 0 5.4%

    \[\leadsto \color{blue}{\frac{-1}{x}} \]
  7. Final simplification5.4%

    \[\leadsto \frac{-1}{x} \]
  8. Add Preprocessing

Developer target: 99.1% accurate, 1.7× speedup?

\[\begin{array}{l} \\ \frac{2}{x \cdot \left(x \cdot x - 1\right)} \end{array} \]
(FPCore (x) :precision binary64 (/ 2.0 (* x (- (* x x) 1.0))))
double code(double x) {
	return 2.0 / (x * ((x * x) - 1.0));
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = 2.0d0 / (x * ((x * x) - 1.0d0))
end function
public static double code(double x) {
	return 2.0 / (x * ((x * x) - 1.0));
}
def code(x):
	return 2.0 / (x * ((x * x) - 1.0))
function code(x)
	return Float64(2.0 / Float64(x * Float64(Float64(x * x) - 1.0)))
end
function tmp = code(x)
	tmp = 2.0 / (x * ((x * x) - 1.0));
end
code[x_] := N[(2.0 / N[(x * N[(N[(x * x), $MachinePrecision] - 1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{2}{x \cdot \left(x \cdot x - 1\right)}
\end{array}

Reproduce

?
herbie shell --seed 2024027 
(FPCore (x)
  :name "3frac (problem 3.3.3)"
  :precision binary64
  :pre (> (fabs x) 1.0)

  :herbie-target
  (/ 2.0 (* x (- (* x x) 1.0)))

  (+ (- (/ 1.0 (+ x 1.0)) (/ 2.0 x)) (/ 1.0 (- x 1.0))))