Rust f32::acosh

Percentage Accurate: 52.8% → 99.5%
Time: 7.5s
Alternatives: 6
Speedup: 1.2×

Specification

?
\[x \geq 1\]
\[\begin{array}{l} \\ \cosh^{-1} x \end{array} \]
(FPCore (x) :precision binary32 (acosh x))
float code(float x) {
	return acoshf(x);
}
function code(x)
	return acosh(x)
end
function tmp = code(x)
	tmp = acosh(x);
end
\begin{array}{l}

\\
\cosh^{-1} x
\end{array}

Sampling outcomes in binary32 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: 52.8% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \log \left(x + \sqrt{x \cdot x - 1}\right) \end{array} \]
(FPCore (x) :precision binary32 (log (+ x (sqrt (- (* x x) 1.0)))))
float code(float x) {
	return logf((x + sqrtf(((x * x) - 1.0f))));
}
real(4) function code(x)
    real(4), intent (in) :: x
    code = log((x + sqrt(((x * x) - 1.0e0))))
end function
function code(x)
	return log(Float32(x + sqrt(Float32(Float32(x * x) - Float32(1.0)))))
end
function tmp = code(x)
	tmp = log((x + sqrt(((x * x) - single(1.0)))));
end
\begin{array}{l}

\\
\log \left(x + \sqrt{x \cdot x - 1}\right)
\end{array}

Alternative 1: 99.5% accurate, 0.8× speedup?

\[\begin{array}{l} \\ \log \left(\frac{1}{\sqrt{\frac{1}{1 + x}}} \cdot \sqrt{x - 1} + x\right) \end{array} \]
(FPCore (x)
 :precision binary32
 (log (+ (* (/ 1.0 (sqrt (/ 1.0 (+ 1.0 x)))) (sqrt (- x 1.0))) x)))
float code(float x) {
	return logf((((1.0f / sqrtf((1.0f / (1.0f + x)))) * sqrtf((x - 1.0f))) + x));
}
real(4) function code(x)
    real(4), intent (in) :: x
    code = log((((1.0e0 / sqrt((1.0e0 / (1.0e0 + x)))) * sqrt((x - 1.0e0))) + x))
end function
function code(x)
	return log(Float32(Float32(Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) / Float32(Float32(1.0) + x)))) * sqrt(Float32(x - Float32(1.0)))) + x))
end
function tmp = code(x)
	tmp = log((((single(1.0) / sqrt((single(1.0) / (single(1.0) + x)))) * sqrt((x - single(1.0)))) + x));
end
\begin{array}{l}

\\
\log \left(\frac{1}{\sqrt{\frac{1}{1 + x}}} \cdot \sqrt{x - 1} + x\right)
\end{array}
Derivation
  1. Initial program 54.2%

    \[\log \left(x + \sqrt{x \cdot x - 1}\right) \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-sqrt.f32N/A

      \[\leadsto \log \left(x + \color{blue}{\sqrt{x \cdot x - 1}}\right) \]
    2. pow1/2N/A

      \[\leadsto \log \left(x + \color{blue}{{\left(x \cdot x - 1\right)}^{\frac{1}{2}}}\right) \]
    3. lift--.f32N/A

      \[\leadsto \log \left(x + {\color{blue}{\left(x \cdot x - 1\right)}}^{\frac{1}{2}}\right) \]
    4. lift-*.f32N/A

      \[\leadsto \log \left(x + {\left(\color{blue}{x \cdot x} - 1\right)}^{\frac{1}{2}}\right) \]
    5. difference-of-sqr-1N/A

      \[\leadsto \log \left(x + {\color{blue}{\left(\left(x + 1\right) \cdot \left(x - 1\right)\right)}}^{\frac{1}{2}}\right) \]
    6. *-commutativeN/A

      \[\leadsto \log \left(x + {\color{blue}{\left(\left(x - 1\right) \cdot \left(x + 1\right)\right)}}^{\frac{1}{2}}\right) \]
    7. unpow-prod-downN/A

      \[\leadsto \log \left(x + \color{blue}{{\left(x - 1\right)}^{\frac{1}{2}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}}\right) \]
    8. lower-*.f32N/A

      \[\leadsto \log \left(x + \color{blue}{{\left(x - 1\right)}^{\frac{1}{2}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}}\right) \]
    9. pow1/2N/A

      \[\leadsto \log \left(x + \color{blue}{\sqrt{x - 1}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}\right) \]
    10. lower-sqrt.f32N/A

      \[\leadsto \log \left(x + \color{blue}{\sqrt{x - 1}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}\right) \]
    11. lower--.f32N/A

      \[\leadsto \log \left(x + \sqrt{\color{blue}{x - 1}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}\right) \]
    12. pow1/2N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \color{blue}{\sqrt{x + 1}}\right) \]
    13. lower-sqrt.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \color{blue}{\sqrt{x + 1}}\right) \]
    14. +-commutativeN/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \sqrt{\color{blue}{1 + x}}\right) \]
    15. lower-+.f3299.2

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \sqrt{\color{blue}{1 + x}}\right) \]
  4. Applied rewrites99.2%

    \[\leadsto \log \left(x + \color{blue}{\sqrt{x - 1} \cdot \sqrt{1 + x}}\right) \]
  5. Step-by-step derivation
    1. lift-sqrt.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \color{blue}{\sqrt{1 + x}}\right) \]
    2. lift-+.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \sqrt{\color{blue}{1 + x}}\right) \]
    3. flip-+N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \sqrt{\color{blue}{\frac{1 \cdot 1 - x \cdot x}{1 - x}}}\right) \]
    4. clear-numN/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \sqrt{\color{blue}{\frac{1}{\frac{1 - x}{1 \cdot 1 - x \cdot x}}}}\right) \]
    5. sqrt-divN/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \color{blue}{\frac{\sqrt{1}}{\sqrt{\frac{1 - x}{1 \cdot 1 - x \cdot x}}}}\right) \]
    6. metadata-evalN/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{\color{blue}{1}}{\sqrt{\frac{1 - x}{1 \cdot 1 - x \cdot x}}}\right) \]
    7. lower-/.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \color{blue}{\frac{1}{\sqrt{\frac{1 - x}{1 \cdot 1 - x \cdot x}}}}\right) \]
    8. lower-sqrt.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\color{blue}{\sqrt{\frac{1 - x}{1 \cdot 1 - x \cdot x}}}}\right) \]
    9. lower-/.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\sqrt{\color{blue}{\frac{1 - x}{1 \cdot 1 - x \cdot x}}}}\right) \]
    10. lower--.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\sqrt{\frac{\color{blue}{1 - x}}{1 \cdot 1 - x \cdot x}}}\right) \]
    11. metadata-evalN/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\sqrt{\frac{1 - x}{\color{blue}{1} - x \cdot x}}}\right) \]
    12. lift-*.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\sqrt{\frac{1 - x}{1 - \color{blue}{x \cdot x}}}}\right) \]
    13. lower--.f3254.3

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\sqrt{\frac{1 - x}{\color{blue}{1 - x \cdot x}}}}\right) \]
  6. Applied rewrites54.3%

    \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \color{blue}{\frac{1}{\sqrt{\frac{1 - x}{1 - x \cdot x}}}}\right) \]
  7. Step-by-step derivation
    1. lift-/.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\sqrt{\color{blue}{\frac{1 - x}{1 - x \cdot x}}}}\right) \]
    2. clear-numN/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\sqrt{\color{blue}{\frac{1}{\frac{1 - x \cdot x}{1 - x}}}}}\right) \]
    3. lift--.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\sqrt{\frac{1}{\frac{\color{blue}{1 - x \cdot x}}{1 - x}}}}\right) \]
    4. metadata-evalN/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\sqrt{\frac{1}{\frac{\color{blue}{1 \cdot 1} - x \cdot x}{1 - x}}}}\right) \]
    5. lift-*.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\sqrt{\frac{1}{\frac{1 \cdot 1 - \color{blue}{x \cdot x}}{1 - x}}}}\right) \]
    6. lift--.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\sqrt{\frac{1}{\frac{1 \cdot 1 - x \cdot x}{\color{blue}{1 - x}}}}}\right) \]
    7. flip-+N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\sqrt{\frac{1}{\color{blue}{1 + x}}}}\right) \]
    8. lift-+.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\sqrt{\frac{1}{\color{blue}{1 + x}}}}\right) \]
    9. lower-/.f3299.2

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \frac{1}{\sqrt{\color{blue}{\frac{1}{1 + x}}}}\right) \]
  8. Applied rewrites99.2%

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

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

Alternative 2: 99.5% accurate, 0.9× speedup?

\[\begin{array}{l} \\ \log \left(\sqrt{1 + x} \cdot \sqrt{x - 1} + x\right) \end{array} \]
(FPCore (x)
 :precision binary32
 (log (+ (* (sqrt (+ 1.0 x)) (sqrt (- x 1.0))) x)))
float code(float x) {
	return logf(((sqrtf((1.0f + x)) * sqrtf((x - 1.0f))) + x));
}
real(4) function code(x)
    real(4), intent (in) :: x
    code = log(((sqrt((1.0e0 + x)) * sqrt((x - 1.0e0))) + x))
end function
function code(x)
	return log(Float32(Float32(sqrt(Float32(Float32(1.0) + x)) * sqrt(Float32(x - Float32(1.0)))) + x))
end
function tmp = code(x)
	tmp = log(((sqrt((single(1.0) + x)) * sqrt((x - single(1.0)))) + x));
end
\begin{array}{l}

\\
\log \left(\sqrt{1 + x} \cdot \sqrt{x - 1} + x\right)
\end{array}
Derivation
  1. Initial program 54.2%

    \[\log \left(x + \sqrt{x \cdot x - 1}\right) \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-sqrt.f32N/A

      \[\leadsto \log \left(x + \color{blue}{\sqrt{x \cdot x - 1}}\right) \]
    2. pow1/2N/A

      \[\leadsto \log \left(x + \color{blue}{{\left(x \cdot x - 1\right)}^{\frac{1}{2}}}\right) \]
    3. lift--.f32N/A

      \[\leadsto \log \left(x + {\color{blue}{\left(x \cdot x - 1\right)}}^{\frac{1}{2}}\right) \]
    4. lift-*.f32N/A

      \[\leadsto \log \left(x + {\left(\color{blue}{x \cdot x} - 1\right)}^{\frac{1}{2}}\right) \]
    5. difference-of-sqr-1N/A

      \[\leadsto \log \left(x + {\color{blue}{\left(\left(x + 1\right) \cdot \left(x - 1\right)\right)}}^{\frac{1}{2}}\right) \]
    6. *-commutativeN/A

      \[\leadsto \log \left(x + {\color{blue}{\left(\left(x - 1\right) \cdot \left(x + 1\right)\right)}}^{\frac{1}{2}}\right) \]
    7. unpow-prod-downN/A

      \[\leadsto \log \left(x + \color{blue}{{\left(x - 1\right)}^{\frac{1}{2}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}}\right) \]
    8. lower-*.f32N/A

      \[\leadsto \log \left(x + \color{blue}{{\left(x - 1\right)}^{\frac{1}{2}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}}\right) \]
    9. pow1/2N/A

      \[\leadsto \log \left(x + \color{blue}{\sqrt{x - 1}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}\right) \]
    10. lower-sqrt.f32N/A

      \[\leadsto \log \left(x + \color{blue}{\sqrt{x - 1}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}\right) \]
    11. lower--.f32N/A

      \[\leadsto \log \left(x + \sqrt{\color{blue}{x - 1}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}\right) \]
    12. pow1/2N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \color{blue}{\sqrt{x + 1}}\right) \]
    13. lower-sqrt.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \color{blue}{\sqrt{x + 1}}\right) \]
    14. +-commutativeN/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \sqrt{\color{blue}{1 + x}}\right) \]
    15. lower-+.f3299.2

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \sqrt{\color{blue}{1 + x}}\right) \]
  4. Applied rewrites99.2%

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

    \[\leadsto \log \left(\sqrt{1 + x} \cdot \sqrt{x - 1} + x\right) \]
  6. Add Preprocessing

Alternative 3: 98.5% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \log \left(\left(2 - \frac{0.5}{x \cdot x}\right) \cdot x\right) \end{array} \]
(FPCore (x) :precision binary32 (log (* (- 2.0 (/ 0.5 (* x x))) x)))
float code(float x) {
	return logf(((2.0f - (0.5f / (x * x))) * x));
}
real(4) function code(x)
    real(4), intent (in) :: x
    code = log(((2.0e0 - (0.5e0 / (x * x))) * x))
end function
function code(x)
	return log(Float32(Float32(Float32(2.0) - Float32(Float32(0.5) / Float32(x * x))) * x))
end
function tmp = code(x)
	tmp = log(((single(2.0) - (single(0.5) / (x * x))) * x));
end
\begin{array}{l}

\\
\log \left(\left(2 - \frac{0.5}{x \cdot x}\right) \cdot x\right)
\end{array}
Derivation
  1. Initial program 54.2%

    \[\log \left(x + \sqrt{x \cdot x - 1}\right) \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-sqrt.f32N/A

      \[\leadsto \log \left(x + \color{blue}{\sqrt{x \cdot x - 1}}\right) \]
    2. pow1/2N/A

      \[\leadsto \log \left(x + \color{blue}{{\left(x \cdot x - 1\right)}^{\frac{1}{2}}}\right) \]
    3. lift--.f32N/A

      \[\leadsto \log \left(x + {\color{blue}{\left(x \cdot x - 1\right)}}^{\frac{1}{2}}\right) \]
    4. lift-*.f32N/A

      \[\leadsto \log \left(x + {\left(\color{blue}{x \cdot x} - 1\right)}^{\frac{1}{2}}\right) \]
    5. difference-of-sqr-1N/A

      \[\leadsto \log \left(x + {\color{blue}{\left(\left(x + 1\right) \cdot \left(x - 1\right)\right)}}^{\frac{1}{2}}\right) \]
    6. *-commutativeN/A

      \[\leadsto \log \left(x + {\color{blue}{\left(\left(x - 1\right) \cdot \left(x + 1\right)\right)}}^{\frac{1}{2}}\right) \]
    7. unpow-prod-downN/A

      \[\leadsto \log \left(x + \color{blue}{{\left(x - 1\right)}^{\frac{1}{2}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}}\right) \]
    8. lower-*.f32N/A

      \[\leadsto \log \left(x + \color{blue}{{\left(x - 1\right)}^{\frac{1}{2}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}}\right) \]
    9. pow1/2N/A

      \[\leadsto \log \left(x + \color{blue}{\sqrt{x - 1}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}\right) \]
    10. lower-sqrt.f32N/A

      \[\leadsto \log \left(x + \color{blue}{\sqrt{x - 1}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}\right) \]
    11. lower--.f32N/A

      \[\leadsto \log \left(x + \sqrt{\color{blue}{x - 1}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}\right) \]
    12. pow1/2N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \color{blue}{\sqrt{x + 1}}\right) \]
    13. lower-sqrt.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \color{blue}{\sqrt{x + 1}}\right) \]
    14. +-commutativeN/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \sqrt{\color{blue}{1 + x}}\right) \]
    15. lower-+.f3299.2

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \sqrt{\color{blue}{1 + x}}\right) \]
  4. Applied rewrites99.2%

    \[\leadsto \log \left(x + \color{blue}{\sqrt{x - 1} \cdot \sqrt{1 + x}}\right) \]
  5. Taylor expanded in x around inf

    \[\leadsto \log \color{blue}{\left(x \cdot \left(2 - \frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right)} \]
  6. Step-by-step derivation
    1. *-commutativeN/A

      \[\leadsto \log \color{blue}{\left(\left(2 - \frac{1}{2} \cdot \frac{1}{{x}^{2}}\right) \cdot x\right)} \]
    2. sub-negN/A

      \[\leadsto \log \left(\color{blue}{\left(2 + \left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right)\right)} \cdot x\right) \]
    3. +-commutativeN/A

      \[\leadsto \log \left(\color{blue}{\left(\left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right) + 2\right)} \cdot x\right) \]
    4. metadata-evalN/A

      \[\leadsto \log \left(\left(\left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right) + \color{blue}{\left(\mathsf{neg}\left(-2\right)\right)}\right) \cdot x\right) \]
    5. metadata-evalN/A

      \[\leadsto \log \left(\left(\left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right) + \left(\mathsf{neg}\left(\color{blue}{\left(-1 - 1\right)}\right)\right)\right) \cdot x\right) \]
    6. rem-square-sqrtN/A

      \[\leadsto \log \left(\left(\left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right) + \left(\mathsf{neg}\left(\left(\color{blue}{\sqrt{-1} \cdot \sqrt{-1}} - 1\right)\right)\right)\right) \cdot x\right) \]
    7. unpow2N/A

      \[\leadsto \log \left(\left(\left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right) + \left(\mathsf{neg}\left(\left(\color{blue}{{\left(\sqrt{-1}\right)}^{2}} - 1\right)\right)\right)\right) \cdot x\right) \]
    8. distribute-neg-inN/A

      \[\leadsto \log \left(\color{blue}{\left(\mathsf{neg}\left(\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}} + \left({\left(\sqrt{-1}\right)}^{2} - 1\right)\right)\right)\right)} \cdot x\right) \]
    9. associate--l+N/A

      \[\leadsto \log \left(\left(\mathsf{neg}\left(\color{blue}{\left(\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}} + {\left(\sqrt{-1}\right)}^{2}\right) - 1\right)}\right)\right) \cdot x\right) \]
    10. lower-*.f32N/A

      \[\leadsto \log \color{blue}{\left(\left(\mathsf{neg}\left(\left(\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}} + {\left(\sqrt{-1}\right)}^{2}\right) - 1\right)\right)\right) \cdot x\right)} \]
  7. Applied rewrites98.0%

    \[\leadsto \log \color{blue}{\left(\left(2 - \frac{0.5}{x \cdot x}\right) \cdot x\right)} \]
  8. Add Preprocessing

Alternative 4: 98.5% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \log \left(\left(x - \frac{0.5}{x}\right) + x\right) \end{array} \]
(FPCore (x) :precision binary32 (log (+ (- x (/ 0.5 x)) x)))
float code(float x) {
	return logf(((x - (0.5f / x)) + x));
}
real(4) function code(x)
    real(4), intent (in) :: x
    code = log(((x - (0.5e0 / x)) + x))
end function
function code(x)
	return log(Float32(Float32(x - Float32(Float32(0.5) / x)) + x))
end
function tmp = code(x)
	tmp = log(((x - (single(0.5) / x)) + x));
end
\begin{array}{l}

\\
\log \left(\left(x - \frac{0.5}{x}\right) + x\right)
\end{array}
Derivation
  1. Initial program 54.2%

    \[\log \left(x + \sqrt{x \cdot x - 1}\right) \]
  2. Add Preprocessing
  3. Taylor expanded in x around inf

    \[\leadsto \log \left(x + \color{blue}{x \cdot \left(1 - \frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)}\right) \]
  4. Step-by-step derivation
    1. sub-negN/A

      \[\leadsto \log \left(x + x \cdot \color{blue}{\left(1 + \left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right)\right)}\right) \]
    2. distribute-lft-inN/A

      \[\leadsto \log \left(x + \color{blue}{\left(x \cdot 1 + x \cdot \left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right)\right)}\right) \]
    3. *-rgt-identityN/A

      \[\leadsto \log \left(x + \left(\color{blue}{x} + x \cdot \left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right)\right)\right) \]
    4. distribute-rgt-neg-outN/A

      \[\leadsto \log \left(x + \left(x + \color{blue}{\left(\mathsf{neg}\left(x \cdot \left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right)\right)}\right)\right) \]
    5. unsub-negN/A

      \[\leadsto \log \left(x + \color{blue}{\left(x - x \cdot \left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right)}\right) \]
    6. remove-double-negN/A

      \[\leadsto \log \left(x + \left(x - \color{blue}{\left(\mathsf{neg}\left(\left(\mathsf{neg}\left(x \cdot \left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right)\right)\right)\right)}\right)\right) \]
    7. distribute-rgt-neg-outN/A

      \[\leadsto \log \left(x + \left(x - \left(\mathsf{neg}\left(\color{blue}{x \cdot \left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right)}\right)\right)\right)\right) \]
    8. distribute-lft-neg-outN/A

      \[\leadsto \log \left(x + \left(x - \color{blue}{\left(\mathsf{neg}\left(x\right)\right) \cdot \left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right)}\right)\right) \]
    9. mul-1-negN/A

      \[\leadsto \log \left(x + \left(x - \color{blue}{\left(-1 \cdot x\right)} \cdot \left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right)\right)\right) \]
    10. *-commutativeN/A

      \[\leadsto \log \left(x + \left(x - \color{blue}{\left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right) \cdot \left(-1 \cdot x\right)}\right)\right) \]
    11. lower--.f32N/A

      \[\leadsto \log \left(x + \color{blue}{\left(x - \left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right) \cdot \left(-1 \cdot x\right)\right)}\right) \]
    12. *-commutativeN/A

      \[\leadsto \log \left(x + \left(x - \color{blue}{\left(-1 \cdot x\right) \cdot \left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right)}\right)\right) \]
    13. mul-1-negN/A

      \[\leadsto \log \left(x + \left(x - \color{blue}{\left(\mathsf{neg}\left(x\right)\right)} \cdot \left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right)\right)\right) \]
    14. distribute-lft-neg-outN/A

      \[\leadsto \log \left(x + \left(x - \color{blue}{\left(\mathsf{neg}\left(x \cdot \left(\mathsf{neg}\left(\frac{1}{2} \cdot \frac{1}{{x}^{2}}\right)\right)\right)\right)}\right)\right) \]
    15. *-commutativeN/A

      \[\leadsto \log \left(x + \left(x - \left(\mathsf{neg}\left(x \cdot \left(\mathsf{neg}\left(\color{blue}{\frac{1}{{x}^{2}} \cdot \frac{1}{2}}\right)\right)\right)\right)\right)\right) \]
    16. distribute-rgt-neg-inN/A

      \[\leadsto \log \left(x + \left(x - \left(\mathsf{neg}\left(x \cdot \color{blue}{\left(\frac{1}{{x}^{2}} \cdot \left(\mathsf{neg}\left(\frac{1}{2}\right)\right)\right)}\right)\right)\right)\right) \]
    17. metadata-evalN/A

      \[\leadsto \log \left(x + \left(x - \left(\mathsf{neg}\left(x \cdot \left(\frac{1}{{x}^{2}} \cdot \color{blue}{\frac{-1}{2}}\right)\right)\right)\right)\right) \]
    18. associate-*r*N/A

      \[\leadsto \log \left(x + \left(x - \left(\mathsf{neg}\left(\color{blue}{\left(x \cdot \frac{1}{{x}^{2}}\right) \cdot \frac{-1}{2}}\right)\right)\right)\right) \]
  5. Applied rewrites98.0%

    \[\leadsto \log \left(x + \color{blue}{\left(x - \frac{0.5}{x}\right)}\right) \]
  6. Final simplification98.0%

    \[\leadsto \log \left(\left(x - \frac{0.5}{x}\right) + x\right) \]
  7. Add Preprocessing

Alternative 5: 97.1% accurate, 1.2× speedup?

\[\begin{array}{l} \\ \log \left(x + x\right) \end{array} \]
(FPCore (x) :precision binary32 (log (+ x x)))
float code(float x) {
	return logf((x + x));
}
real(4) function code(x)
    real(4), intent (in) :: x
    code = log((x + x))
end function
function code(x)
	return log(Float32(x + x))
end
function tmp = code(x)
	tmp = log((x + x));
end
\begin{array}{l}

\\
\log \left(x + x\right)
\end{array}
Derivation
  1. Initial program 54.2%

    \[\log \left(x + \sqrt{x \cdot x - 1}\right) \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-sqrt.f32N/A

      \[\leadsto \log \left(x + \color{blue}{\sqrt{x \cdot x - 1}}\right) \]
    2. pow1/2N/A

      \[\leadsto \log \left(x + \color{blue}{{\left(x \cdot x - 1\right)}^{\frac{1}{2}}}\right) \]
    3. lift--.f32N/A

      \[\leadsto \log \left(x + {\color{blue}{\left(x \cdot x - 1\right)}}^{\frac{1}{2}}\right) \]
    4. lift-*.f32N/A

      \[\leadsto \log \left(x + {\left(\color{blue}{x \cdot x} - 1\right)}^{\frac{1}{2}}\right) \]
    5. difference-of-sqr-1N/A

      \[\leadsto \log \left(x + {\color{blue}{\left(\left(x + 1\right) \cdot \left(x - 1\right)\right)}}^{\frac{1}{2}}\right) \]
    6. *-commutativeN/A

      \[\leadsto \log \left(x + {\color{blue}{\left(\left(x - 1\right) \cdot \left(x + 1\right)\right)}}^{\frac{1}{2}}\right) \]
    7. unpow-prod-downN/A

      \[\leadsto \log \left(x + \color{blue}{{\left(x - 1\right)}^{\frac{1}{2}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}}\right) \]
    8. lower-*.f32N/A

      \[\leadsto \log \left(x + \color{blue}{{\left(x - 1\right)}^{\frac{1}{2}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}}\right) \]
    9. pow1/2N/A

      \[\leadsto \log \left(x + \color{blue}{\sqrt{x - 1}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}\right) \]
    10. lower-sqrt.f32N/A

      \[\leadsto \log \left(x + \color{blue}{\sqrt{x - 1}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}\right) \]
    11. lower--.f32N/A

      \[\leadsto \log \left(x + \sqrt{\color{blue}{x - 1}} \cdot {\left(x + 1\right)}^{\frac{1}{2}}\right) \]
    12. pow1/2N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \color{blue}{\sqrt{x + 1}}\right) \]
    13. lower-sqrt.f32N/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \color{blue}{\sqrt{x + 1}}\right) \]
    14. +-commutativeN/A

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \sqrt{\color{blue}{1 + x}}\right) \]
    15. lower-+.f3299.2

      \[\leadsto \log \left(x + \sqrt{x - 1} \cdot \sqrt{\color{blue}{1 + x}}\right) \]
  4. Applied rewrites99.2%

    \[\leadsto \log \left(x + \color{blue}{\sqrt{x - 1} \cdot \sqrt{1 + x}}\right) \]
  5. Taylor expanded in x around -inf

    \[\leadsto \log \left(x + \color{blue}{-1 \cdot \left(x \cdot {\left(\sqrt{-1}\right)}^{2}\right)}\right) \]
  6. Step-by-step derivation
    1. *-commutativeN/A

      \[\leadsto \log \left(x + -1 \cdot \color{blue}{\left({\left(\sqrt{-1}\right)}^{2} \cdot x\right)}\right) \]
    2. unpow2N/A

      \[\leadsto \log \left(x + -1 \cdot \left(\color{blue}{\left(\sqrt{-1} \cdot \sqrt{-1}\right)} \cdot x\right)\right) \]
    3. rem-square-sqrtN/A

      \[\leadsto \log \left(x + -1 \cdot \left(\color{blue}{-1} \cdot x\right)\right) \]
    4. neg-mul-1N/A

      \[\leadsto \log \left(x + \color{blue}{\left(\mathsf{neg}\left(-1 \cdot x\right)\right)}\right) \]
    5. mul-1-negN/A

      \[\leadsto \log \left(x + \left(\mathsf{neg}\left(\color{blue}{\left(\mathsf{neg}\left(x\right)\right)}\right)\right)\right) \]
    6. remove-double-neg96.5

      \[\leadsto \log \left(x + \color{blue}{x}\right) \]
  7. Applied rewrites96.5%

    \[\leadsto \log \left(x + \color{blue}{x}\right) \]
  8. Final simplification96.5%

    \[\leadsto \log \left(x + x\right) \]
  9. Add Preprocessing

Alternative 6: 1.3% accurate, 1.2× speedup?

\[\begin{array}{l} \\ \log 0 \end{array} \]
(FPCore (x) :precision binary32 (log 0.0))
float code(float x) {
	return logf(0.0f);
}
real(4) function code(x)
    real(4), intent (in) :: x
    code = log(0.0e0)
end function
function code(x)
	return log(Float32(0.0))
end
function tmp = code(x)
	tmp = log(single(0.0));
end
\begin{array}{l}

\\
\log 0
\end{array}
Derivation
  1. Initial program 54.2%

    \[\log \left(x + \sqrt{x \cdot x - 1}\right) \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift--.f32N/A

      \[\leadsto \log \left(x + \sqrt{\color{blue}{x \cdot x - 1}}\right) \]
    2. sub-negN/A

      \[\leadsto \log \left(x + \sqrt{\color{blue}{x \cdot x + \left(\mathsf{neg}\left(1\right)\right)}}\right) \]
    3. +-commutativeN/A

      \[\leadsto \log \left(x + \sqrt{\color{blue}{\left(\mathsf{neg}\left(1\right)\right) + x \cdot x}}\right) \]
    4. flip-+N/A

      \[\leadsto \log \left(x + \sqrt{\color{blue}{\frac{\left(\mathsf{neg}\left(1\right)\right) \cdot \left(\mathsf{neg}\left(1\right)\right) - \left(x \cdot x\right) \cdot \left(x \cdot x\right)}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}}\right) \]
    5. metadata-evalN/A

      \[\leadsto \log \left(x + \sqrt{\frac{\color{blue}{-1} \cdot \left(\mathsf{neg}\left(1\right)\right) - \left(x \cdot x\right) \cdot \left(x \cdot x\right)}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}\right) \]
    6. metadata-evalN/A

      \[\leadsto \log \left(x + \sqrt{\frac{-1 \cdot \color{blue}{-1} - \left(x \cdot x\right) \cdot \left(x \cdot x\right)}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}\right) \]
    7. metadata-evalN/A

      \[\leadsto \log \left(x + \sqrt{\frac{\color{blue}{1} - \left(x \cdot x\right) \cdot \left(x \cdot x\right)}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}\right) \]
    8. metadata-evalN/A

      \[\leadsto \log \left(x + \sqrt{\frac{\color{blue}{1 \cdot 1} - \left(x \cdot x\right) \cdot \left(x \cdot x\right)}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}\right) \]
    9. lower-/.f32N/A

      \[\leadsto \log \left(x + \sqrt{\color{blue}{\frac{1 \cdot 1 - \left(x \cdot x\right) \cdot \left(x \cdot x\right)}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}}\right) \]
    10. metadata-evalN/A

      \[\leadsto \log \left(x + \sqrt{\frac{\color{blue}{1} - \left(x \cdot x\right) \cdot \left(x \cdot x\right)}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}\right) \]
    11. lower--.f32N/A

      \[\leadsto \log \left(x + \sqrt{\frac{\color{blue}{1 - \left(x \cdot x\right) \cdot \left(x \cdot x\right)}}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}\right) \]
    12. pow2N/A

      \[\leadsto \log \left(x + \sqrt{\frac{1 - \color{blue}{{\left(x \cdot x\right)}^{2}}}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}\right) \]
    13. lift-*.f32N/A

      \[\leadsto \log \left(x + \sqrt{\frac{1 - {\color{blue}{\left(x \cdot x\right)}}^{2}}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}\right) \]
    14. pow-prod-downN/A

      \[\leadsto \log \left(x + \sqrt{\frac{1 - \color{blue}{{x}^{2} \cdot {x}^{2}}}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}\right) \]
    15. pow-prod-upN/A

      \[\leadsto \log \left(x + \sqrt{\frac{1 - \color{blue}{{x}^{\left(2 + 2\right)}}}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}\right) \]
    16. lower-pow.f32N/A

      \[\leadsto \log \left(x + \sqrt{\frac{1 - \color{blue}{{x}^{\left(2 + 2\right)}}}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}\right) \]
    17. metadata-evalN/A

      \[\leadsto \log \left(x + \sqrt{\frac{1 - {x}^{\color{blue}{4}}}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}\right) \]
    18. lower--.f32N/A

      \[\leadsto \log \left(x + \sqrt{\frac{1 - {x}^{4}}{\color{blue}{\left(\mathsf{neg}\left(1\right)\right) - x \cdot x}}}\right) \]
    19. metadata-eval30.3

      \[\leadsto \log \left(x + \sqrt{\frac{1 - {x}^{4}}{\color{blue}{-1} - x \cdot x}}\right) \]
  4. Applied rewrites30.3%

    \[\leadsto \log \left(x + \sqrt{\color{blue}{\frac{1 - {x}^{4}}{-1 - x \cdot x}}}\right) \]
  5. Taylor expanded in x around inf

    \[\leadsto \log \color{blue}{\left(x \cdot \left(1 + {\left(\sqrt{-1}\right)}^{2}\right)\right)} \]
  6. Step-by-step derivation
    1. +-commutativeN/A

      \[\leadsto \log \left(x \cdot \color{blue}{\left({\left(\sqrt{-1}\right)}^{2} + 1\right)}\right) \]
    2. unpow2N/A

      \[\leadsto \log \left(x \cdot \left(\color{blue}{\sqrt{-1} \cdot \sqrt{-1}} + 1\right)\right) \]
    3. rem-square-sqrtN/A

      \[\leadsto \log \left(x \cdot \left(\color{blue}{-1} + 1\right)\right) \]
    4. metadata-evalN/A

      \[\leadsto \log \left(x \cdot \color{blue}{0}\right) \]
    5. mul0-rgt1.3

      \[\leadsto \log \color{blue}{0} \]
  7. Applied rewrites1.3%

    \[\leadsto \log \color{blue}{0} \]
  8. Add Preprocessing

Developer Target 1: 99.5% accurate, 0.9× speedup?

\[\begin{array}{l} \\ \log \left(x + \sqrt{x - 1} \cdot \sqrt{x + 1}\right) \end{array} \]
(FPCore (x)
 :precision binary32
 (log (+ x (* (sqrt (- x 1.0)) (sqrt (+ x 1.0))))))
float code(float x) {
	return logf((x + (sqrtf((x - 1.0f)) * sqrtf((x + 1.0f)))));
}
real(4) function code(x)
    real(4), intent (in) :: x
    code = log((x + (sqrt((x - 1.0e0)) * sqrt((x + 1.0e0)))))
end function
function code(x)
	return log(Float32(x + Float32(sqrt(Float32(x - Float32(1.0))) * sqrt(Float32(x + Float32(1.0))))))
end
function tmp = code(x)
	tmp = log((x + (sqrt((x - single(1.0))) * sqrt((x + single(1.0))))));
end
\begin{array}{l}

\\
\log \left(x + \sqrt{x - 1} \cdot \sqrt{x + 1}\right)
\end{array}

Reproduce

?
herbie shell --seed 2024277 
(FPCore (x)
  :name "Rust f32::acosh"
  :precision binary32
  :pre (>= x 1.0)

  :alt
  (! :herbie-platform default (log (+ x (* (sqrt (- x 1)) (sqrt (+ x 1))))))

  (log (+ x (sqrt (- (* x x) 1.0)))))