neg log

Percentage Accurate: 100.0% → 100.0%
Time: 6.9s
Alternatives: 7
Speedup: 1.0×

Specification

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

\\
-\log \left(\frac{1}{x} - 1\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 7 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: 100.0% accurate, 1.0× speedup?

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

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

Alternative 1: 100.0% accurate, 1.0× speedup?

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

\\
-\log \left(\frac{1}{x} + -1\right)
\end{array}
Derivation
  1. Initial program 100.0%

    \[-\log \left(\frac{1}{x} - 1\right) \]
  2. Add Preprocessing
  3. Final simplification100.0%

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

Alternative 2: 99.3% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5, 1\right), \log x\right) \end{array} \]
(FPCore (x) :precision binary64 (fma x (fma x 0.5 1.0) (log x)))
double code(double x) {
	return fma(x, fma(x, 0.5, 1.0), log(x));
}
function code(x)
	return fma(x, fma(x, 0.5, 1.0), log(x))
end
code[x_] := N[(x * N[(x * 0.5 + 1.0), $MachinePrecision] + N[Log[x], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5, 1\right), \log x\right)
\end{array}
Derivation
  1. Initial program 100.0%

    \[-\log \left(\frac{1}{x} - 1\right) \]
  2. Add Preprocessing
  3. Taylor expanded in x around 0

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

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

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

      \[\leadsto x \cdot \left(1 + \frac{1}{2} \cdot x\right) + \color{blue}{\log x} \]
    4. lower-fma.f64N/A

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

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

      \[\leadsto \mathsf{fma}\left(x, \color{blue}{x \cdot \frac{1}{2}} + 1, \log x\right) \]
    7. lower-fma.f64N/A

      \[\leadsto \mathsf{fma}\left(x, \color{blue}{\mathsf{fma}\left(x, \frac{1}{2}, 1\right)}, \log x\right) \]
    8. lower-log.f6499.6

      \[\leadsto \mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5, 1\right), \color{blue}{\log x}\right) \]
  5. Applied rewrites99.6%

    \[\leadsto \color{blue}{\mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5, 1\right), \log x\right)} \]
  6. Add Preprocessing

Alternative 3: 99.0% accurate, 1.1× speedup?

\[\begin{array}{l} \\ x + \log x \end{array} \]
(FPCore (x) :precision binary64 (+ x (log x)))
double code(double x) {
	return x + log(x);
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = x + log(x)
end function
public static double code(double x) {
	return x + Math.log(x);
}
def code(x):
	return x + math.log(x)
function code(x)
	return Float64(x + log(x))
end
function tmp = code(x)
	tmp = x + log(x);
end
code[x_] := N[(x + N[Log[x], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
x + \log x
\end{array}
Derivation
  1. Initial program 100.0%

    \[-\log \left(\frac{1}{x} - 1\right) \]
  2. Add Preprocessing
  3. Taylor expanded in x around 0

    \[\leadsto \color{blue}{x - -1 \cdot \log x} \]
  4. Step-by-step derivation
    1. sub-negN/A

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

      \[\leadsto x + \left(\mathsf{neg}\left(\color{blue}{\left(\mathsf{neg}\left(\log x\right)\right)}\right)\right) \]
    3. remove-double-negN/A

      \[\leadsto x + \color{blue}{\log x} \]
    4. lower-+.f64N/A

      \[\leadsto \color{blue}{x + \log x} \]
    5. lower-log.f6499.3

      \[\leadsto x + \color{blue}{\log x} \]
  5. Applied rewrites99.3%

    \[\leadsto \color{blue}{x + \log x} \]
  6. Add Preprocessing

Alternative 4: 98.0% accurate, 1.2× speedup?

\[\begin{array}{l} \\ \log x \end{array} \]
(FPCore (x) :precision binary64 (log x))
double code(double x) {
	return log(x);
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = log(x)
end function
public static double code(double x) {
	return Math.log(x);
}
def code(x):
	return math.log(x)
function code(x)
	return log(x)
end
function tmp = code(x)
	tmp = log(x);
end
code[x_] := N[Log[x], $MachinePrecision]
\begin{array}{l}

\\
\log x
\end{array}
Derivation
  1. Initial program 100.0%

    \[-\log \left(\frac{1}{x} - 1\right) \]
  2. Add Preprocessing
  3. Taylor expanded in x around 0

    \[\leadsto \color{blue}{\log x} \]
  4. Step-by-step derivation
    1. lower-log.f6498.1

      \[\leadsto \color{blue}{\log x} \]
  5. Applied rewrites98.1%

    \[\leadsto \color{blue}{\log x} \]
  6. Add Preprocessing

Alternative 5: 7.1% accurate, 1.4× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;\frac{1}{x} \leq 5 \cdot 10^{+106}:\\ \;\;\;\;\frac{\mathsf{fma}\left(x, \left(x \cdot x\right) \cdot 0.125, 1\right) \cdot \left(x \cdot \left(x \cdot x\right)\right)}{\left(x \cdot x\right) \cdot \left(x \cdot \mathsf{fma}\left(x, 0.25, -0.5\right)\right)}\\ \mathbf{else}:\\ \;\;\;\;\frac{0.5}{\frac{1}{x \cdot x}}\\ \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (if (<= (/ 1.0 x) 5e+106)
   (/
    (* (fma x (* (* x x) 0.125) 1.0) (* x (* x x)))
    (* (* x x) (* x (fma x 0.25 -0.5))))
   (/ 0.5 (/ 1.0 (* x x)))))
double code(double x) {
	double tmp;
	if ((1.0 / x) <= 5e+106) {
		tmp = (fma(x, ((x * x) * 0.125), 1.0) * (x * (x * x))) / ((x * x) * (x * fma(x, 0.25, -0.5)));
	} else {
		tmp = 0.5 / (1.0 / (x * x));
	}
	return tmp;
}
function code(x)
	tmp = 0.0
	if (Float64(1.0 / x) <= 5e+106)
		tmp = Float64(Float64(fma(x, Float64(Float64(x * x) * 0.125), 1.0) * Float64(x * Float64(x * x))) / Float64(Float64(x * x) * Float64(x * fma(x, 0.25, -0.5))));
	else
		tmp = Float64(0.5 / Float64(1.0 / Float64(x * x)));
	end
	return tmp
end
code[x_] := If[LessEqual[N[(1.0 / x), $MachinePrecision], 5e+106], N[(N[(N[(x * N[(N[(x * x), $MachinePrecision] * 0.125), $MachinePrecision] + 1.0), $MachinePrecision] * N[(x * N[(x * x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(N[(x * x), $MachinePrecision] * N[(x * N[(x * 0.25 + -0.5), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(0.5 / N[(1.0 / N[(x * x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;\frac{1}{x} \leq 5 \cdot 10^{+106}:\\
\;\;\;\;\frac{\mathsf{fma}\left(x, \left(x \cdot x\right) \cdot 0.125, 1\right) \cdot \left(x \cdot \left(x \cdot x\right)\right)}{\left(x \cdot x\right) \cdot \left(x \cdot \mathsf{fma}\left(x, 0.25, -0.5\right)\right)}\\

\mathbf{else}:\\
\;\;\;\;\frac{0.5}{\frac{1}{x \cdot x}}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (/.f64 #s(literal 1 binary64) x) < 4.9999999999999998e106

    1. Initial program 100.0%

      \[-\log \left(\frac{1}{x} - 1\right) \]
    2. Add Preprocessing
    3. Taylor expanded in x around 0

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

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

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

        \[\leadsto x \cdot \left(1 + \frac{1}{2} \cdot x\right) + \color{blue}{\log x} \]
      4. lower-fma.f64N/A

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

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

        \[\leadsto \mathsf{fma}\left(x, \color{blue}{x \cdot \frac{1}{2}} + 1, \log x\right) \]
      7. lower-fma.f64N/A

        \[\leadsto \mathsf{fma}\left(x, \color{blue}{\mathsf{fma}\left(x, \frac{1}{2}, 1\right)}, \log x\right) \]
      8. lower-log.f6498.9

        \[\leadsto \mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5, 1\right), \color{blue}{\log x}\right) \]
    5. Applied rewrites98.9%

      \[\leadsto \color{blue}{\mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5, 1\right), \log x\right)} \]
    6. Taylor expanded in x around inf

      \[\leadsto {x}^{2} \cdot \color{blue}{\left(\frac{1}{2} + \frac{1}{x}\right)} \]
    7. Step-by-step derivation
      1. Applied rewrites1.9%

        \[\leadsto \mathsf{fma}\left(x, \color{blue}{x \cdot 0.5}, x\right) \]
      2. Applied rewrites1.9%

        \[\leadsto \frac{\mathsf{fma}\left(x, \left(x \cdot x\right) \cdot 0.125, 1\right) \cdot \left(x \cdot \left(x \cdot x\right)\right)}{\mathsf{fma}\left(x, \color{blue}{x}, \left(x \cdot x\right) \cdot \left(x \cdot \left(x \cdot 0.25 - 0.5\right)\right)\right)} \]
      3. Taylor expanded in x around inf

        \[\leadsto \frac{\mathsf{fma}\left(x, \left(x \cdot x\right) \cdot \frac{1}{8}, 1\right) \cdot \left(x \cdot \left(x \cdot x\right)\right)}{{x}^{4} \cdot \left(\frac{1}{4} - \color{blue}{\frac{1}{2} \cdot \frac{1}{x}}\right)} \]
      4. Step-by-step derivation
        1. Applied rewrites14.8%

          \[\leadsto \frac{\mathsf{fma}\left(x, \left(x \cdot x\right) \cdot 0.125, 1\right) \cdot \left(x \cdot \left(x \cdot x\right)\right)}{\left(x \cdot x\right) \cdot \left(x \cdot \color{blue}{\mathsf{fma}\left(x, 0.25, -0.5\right)}\right)} \]

        if 4.9999999999999998e106 < (/.f64 #s(literal 1 binary64) x)

        1. Initial program 100.0%

          \[-\log \left(\frac{1}{x} - 1\right) \]
        2. Add Preprocessing
        3. Taylor expanded in x around 0

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

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

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

            \[\leadsto x \cdot \left(1 + \frac{1}{2} \cdot x\right) + \color{blue}{\log x} \]
          4. lower-fma.f64N/A

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

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

            \[\leadsto \mathsf{fma}\left(x, \color{blue}{x \cdot \frac{1}{2}} + 1, \log x\right) \]
          7. lower-fma.f64N/A

            \[\leadsto \mathsf{fma}\left(x, \color{blue}{\mathsf{fma}\left(x, \frac{1}{2}, 1\right)}, \log x\right) \]
          8. lower-log.f64100.0

            \[\leadsto \mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5, 1\right), \color{blue}{\log x}\right) \]
        5. Applied rewrites100.0%

          \[\leadsto \color{blue}{\mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5, 1\right), \log x\right)} \]
        6. Step-by-step derivation
          1. Applied rewrites100.0%

            \[\leadsto \mathsf{fma}\left(x \cdot x, \color{blue}{0.5}, x + \log x\right) \]
          2. Taylor expanded in x around inf

            \[\leadsto \frac{1}{2} \cdot \color{blue}{{x}^{2}} \]
          3. Step-by-step derivation
            1. Applied rewrites3.0%

              \[\leadsto 0.5 \cdot \color{blue}{\left(x \cdot x\right)} \]
            2. Step-by-step derivation
              1. Applied rewrites3.0%

                \[\leadsto \frac{0.5}{\frac{1}{\color{blue}{x \cdot x}}} \]
            3. Recombined 2 regimes into one program.
            4. Add Preprocessing

            Alternative 6: 2.7% accurate, 4.2× speedup?

            \[\begin{array}{l} \\ \frac{0.5}{\frac{1}{x \cdot x}} \end{array} \]
            (FPCore (x) :precision binary64 (/ 0.5 (/ 1.0 (* x x))))
            double code(double x) {
            	return 0.5 / (1.0 / (x * x));
            }
            
            real(8) function code(x)
                real(8), intent (in) :: x
                code = 0.5d0 / (1.0d0 / (x * x))
            end function
            
            public static double code(double x) {
            	return 0.5 / (1.0 / (x * x));
            }
            
            def code(x):
            	return 0.5 / (1.0 / (x * x))
            
            function code(x)
            	return Float64(0.5 / Float64(1.0 / Float64(x * x)))
            end
            
            function tmp = code(x)
            	tmp = 0.5 / (1.0 / (x * x));
            end
            
            code[x_] := N[(0.5 / N[(1.0 / N[(x * x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
            
            \begin{array}{l}
            
            \\
            \frac{0.5}{\frac{1}{x \cdot x}}
            \end{array}
            
            Derivation
            1. Initial program 100.0%

              \[-\log \left(\frac{1}{x} - 1\right) \]
            2. Add Preprocessing
            3. Taylor expanded in x around 0

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

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

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

                \[\leadsto x \cdot \left(1 + \frac{1}{2} \cdot x\right) + \color{blue}{\log x} \]
              4. lower-fma.f64N/A

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

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

                \[\leadsto \mathsf{fma}\left(x, \color{blue}{x \cdot \frac{1}{2}} + 1, \log x\right) \]
              7. lower-fma.f64N/A

                \[\leadsto \mathsf{fma}\left(x, \color{blue}{\mathsf{fma}\left(x, \frac{1}{2}, 1\right)}, \log x\right) \]
              8. lower-log.f6499.6

                \[\leadsto \mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5, 1\right), \color{blue}{\log x}\right) \]
            5. Applied rewrites99.6%

              \[\leadsto \color{blue}{\mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5, 1\right), \log x\right)} \]
            6. Step-by-step derivation
              1. Applied rewrites99.6%

                \[\leadsto \mathsf{fma}\left(x \cdot x, \color{blue}{0.5}, x + \log x\right) \]
              2. Taylor expanded in x around inf

                \[\leadsto \frac{1}{2} \cdot \color{blue}{{x}^{2}} \]
              3. Step-by-step derivation
                1. Applied rewrites2.7%

                  \[\leadsto 0.5 \cdot \color{blue}{\left(x \cdot x\right)} \]
                2. Step-by-step derivation
                  1. Applied rewrites2.7%

                    \[\leadsto \frac{0.5}{\frac{1}{\color{blue}{x \cdot x}}} \]
                  2. Add Preprocessing

                  Alternative 7: 2.7% accurate, 10.6× speedup?

                  \[\begin{array}{l} \\ x \cdot \left(x \cdot 0.5\right) \end{array} \]
                  (FPCore (x) :precision binary64 (* x (* x 0.5)))
                  double code(double x) {
                  	return x * (x * 0.5);
                  }
                  
                  real(8) function code(x)
                      real(8), intent (in) :: x
                      code = x * (x * 0.5d0)
                  end function
                  
                  public static double code(double x) {
                  	return x * (x * 0.5);
                  }
                  
                  def code(x):
                  	return x * (x * 0.5)
                  
                  function code(x)
                  	return Float64(x * Float64(x * 0.5))
                  end
                  
                  function tmp = code(x)
                  	tmp = x * (x * 0.5);
                  end
                  
                  code[x_] := N[(x * N[(x * 0.5), $MachinePrecision]), $MachinePrecision]
                  
                  \begin{array}{l}
                  
                  \\
                  x \cdot \left(x \cdot 0.5\right)
                  \end{array}
                  
                  Derivation
                  1. Initial program 100.0%

                    \[-\log \left(\frac{1}{x} - 1\right) \]
                  2. Add Preprocessing
                  3. Taylor expanded in x around 0

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

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

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

                      \[\leadsto x \cdot \left(1 + \frac{1}{2} \cdot x\right) + \color{blue}{\log x} \]
                    4. lower-fma.f64N/A

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

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

                      \[\leadsto \mathsf{fma}\left(x, \color{blue}{x \cdot \frac{1}{2}} + 1, \log x\right) \]
                    7. lower-fma.f64N/A

                      \[\leadsto \mathsf{fma}\left(x, \color{blue}{\mathsf{fma}\left(x, \frac{1}{2}, 1\right)}, \log x\right) \]
                    8. lower-log.f6499.6

                      \[\leadsto \mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5, 1\right), \color{blue}{\log x}\right) \]
                  5. Applied rewrites99.6%

                    \[\leadsto \color{blue}{\mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5, 1\right), \log x\right)} \]
                  6. Taylor expanded in x around inf

                    \[\leadsto \frac{1}{2} \cdot \color{blue}{{x}^{2}} \]
                  7. Step-by-step derivation
                    1. Applied rewrites2.7%

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

                    Reproduce

                    ?
                    herbie shell --seed 2024234 
                    (FPCore (x)
                      :name "neg log"
                      :precision binary64
                      (- (log (- (/ 1.0 x) 1.0))))