expm1 (example 3.7)

Percentage Accurate: 8.7% → 100.0%
Time: 4.1s
Alternatives: 9
Speedup: 17.3×

Specification

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

\\
e^{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 9 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: 8.7% accurate, 1.0× speedup?

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

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

Alternative 1: 100.0% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \mathsf{expm1}\left(x\right) \end{array} \]
(FPCore (x) :precision binary64 (expm1 x))
double code(double x) {
	return expm1(x);
}
public static double code(double x) {
	return Math.expm1(x);
}
def code(x):
	return math.expm1(x)
function code(x)
	return expm1(x)
end
code[x_] := N[(Exp[x] - 1), $MachinePrecision]
\begin{array}{l}

\\
\mathsf{expm1}\left(x\right)
\end{array}
Derivation
  1. Initial program 9.6%

    \[e^{x} - 1 \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift--.f64N/A

      \[\leadsto \color{blue}{e^{x} - 1} \]
    2. lift-exp.f64N/A

      \[\leadsto \color{blue}{e^{x}} - 1 \]
    3. lower-expm1.f64100.0

      \[\leadsto \color{blue}{\mathsf{expm1}\left(x\right)} \]
  4. Applied rewrites100.0%

    \[\leadsto \color{blue}{\mathsf{expm1}\left(x\right)} \]
  5. Add Preprocessing

Alternative 2: 99.5% accurate, 4.3× speedup?

\[\begin{array}{l} \\ \frac{x}{\mathsf{fma}\left(\mathsf{fma}\left(0.08333333333333333, x, -0.5\right), x, 1\right)} \end{array} \]
(FPCore (x)
 :precision binary64
 (/ x (fma (fma 0.08333333333333333 x -0.5) x 1.0)))
double code(double x) {
	return x / fma(fma(0.08333333333333333, x, -0.5), x, 1.0);
}
function code(x)
	return Float64(x / fma(fma(0.08333333333333333, x, -0.5), x, 1.0))
end
code[x_] := N[(x / N[(N[(0.08333333333333333 * x + -0.5), $MachinePrecision] * x + 1.0), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{x}{\mathsf{fma}\left(\mathsf{fma}\left(0.08333333333333333, x, -0.5\right), x, 1\right)}
\end{array}
Derivation
  1. Initial program 9.6%

    \[e^{x} - 1 \]
  2. Add Preprocessing
  3. Taylor expanded in x around 0

    \[\leadsto \color{blue}{x \cdot \left(1 + x \cdot \left(\frac{1}{2} + x \cdot \left(\frac{1}{6} + \frac{1}{24} \cdot x\right)\right)\right)} \]
  4. Step-by-step derivation
    1. *-commutativeN/A

      \[\leadsto \color{blue}{\left(1 + x \cdot \left(\frac{1}{2} + x \cdot \left(\frac{1}{6} + \frac{1}{24} \cdot x\right)\right)\right) \cdot x} \]
    2. lower-*.f64N/A

      \[\leadsto \color{blue}{\left(1 + x \cdot \left(\frac{1}{2} + x \cdot \left(\frac{1}{6} + \frac{1}{24} \cdot x\right)\right)\right) \cdot x} \]
    3. +-commutativeN/A

      \[\leadsto \color{blue}{\left(x \cdot \left(\frac{1}{2} + x \cdot \left(\frac{1}{6} + \frac{1}{24} \cdot x\right)\right) + 1\right)} \cdot x \]
    4. *-commutativeN/A

      \[\leadsto \left(\color{blue}{\left(\frac{1}{2} + x \cdot \left(\frac{1}{6} + \frac{1}{24} \cdot x\right)\right) \cdot x} + 1\right) \cdot x \]
    5. lower-fma.f64N/A

      \[\leadsto \color{blue}{\mathsf{fma}\left(\frac{1}{2} + x \cdot \left(\frac{1}{6} + \frac{1}{24} \cdot x\right), x, 1\right)} \cdot x \]
    6. +-commutativeN/A

      \[\leadsto \mathsf{fma}\left(\color{blue}{x \cdot \left(\frac{1}{6} + \frac{1}{24} \cdot x\right) + \frac{1}{2}}, x, 1\right) \cdot x \]
    7. *-commutativeN/A

      \[\leadsto \mathsf{fma}\left(\color{blue}{\left(\frac{1}{6} + \frac{1}{24} \cdot x\right) \cdot x} + \frac{1}{2}, x, 1\right) \cdot x \]
    8. lower-fma.f64N/A

      \[\leadsto \mathsf{fma}\left(\color{blue}{\mathsf{fma}\left(\frac{1}{6} + \frac{1}{24} \cdot x, x, \frac{1}{2}\right)}, x, 1\right) \cdot x \]
    9. +-commutativeN/A

      \[\leadsto \mathsf{fma}\left(\mathsf{fma}\left(\color{blue}{\frac{1}{24} \cdot x + \frac{1}{6}}, x, \frac{1}{2}\right), x, 1\right) \cdot x \]
    10. lower-fma.f6499.3

      \[\leadsto \mathsf{fma}\left(\mathsf{fma}\left(\color{blue}{\mathsf{fma}\left(0.041666666666666664, x, 0.16666666666666666\right)}, x, 0.5\right), x, 1\right) \cdot x \]
  5. Applied rewrites99.3%

    \[\leadsto \color{blue}{\mathsf{fma}\left(\mathsf{fma}\left(\mathsf{fma}\left(0.041666666666666664, x, 0.16666666666666666\right), x, 0.5\right), x, 1\right) \cdot x} \]
  6. Step-by-step derivation
    1. Applied rewrites99.3%

      \[\leadsto \frac{x}{\color{blue}{\frac{1}{\mathsf{fma}\left(\mathsf{fma}\left(\mathsf{fma}\left(0.041666666666666664, x, 0.16666666666666666\right), x, 0.5\right), x, 1\right)}}} \]
    2. Taylor expanded in x around 0

      \[\leadsto \frac{x}{1 + \color{blue}{x \cdot \left(\frac{1}{12} \cdot x - \frac{1}{2}\right)}} \]
    3. Step-by-step derivation
      1. Applied rewrites99.4%

        \[\leadsto \frac{x}{\mathsf{fma}\left(\mathsf{fma}\left(0.08333333333333333, x, -0.5\right), \color{blue}{x}, 1\right)} \]
      2. Add Preprocessing

      Alternative 3: 99.5% accurate, 4.3× speedup?

      \[\begin{array}{l} \\ \mathsf{fma}\left(\mathsf{fma}\left(\mathsf{fma}\left(0.041666666666666664, x, 0.16666666666666666\right), x, 0.5\right), x, 1\right) \cdot x \end{array} \]
      (FPCore (x)
       :precision binary64
       (*
        (fma (fma (fma 0.041666666666666664 x 0.16666666666666666) x 0.5) x 1.0)
        x))
      double code(double x) {
      	return fma(fma(fma(0.041666666666666664, x, 0.16666666666666666), x, 0.5), x, 1.0) * x;
      }
      
      function code(x)
      	return Float64(fma(fma(fma(0.041666666666666664, x, 0.16666666666666666), x, 0.5), x, 1.0) * x)
      end
      
      code[x_] := N[(N[(N[(N[(0.041666666666666664 * x + 0.16666666666666666), $MachinePrecision] * x + 0.5), $MachinePrecision] * x + 1.0), $MachinePrecision] * x), $MachinePrecision]
      
      \begin{array}{l}
      
      \\
      \mathsf{fma}\left(\mathsf{fma}\left(\mathsf{fma}\left(0.041666666666666664, x, 0.16666666666666666\right), x, 0.5\right), x, 1\right) \cdot x
      \end{array}
      
      Derivation
      1. Initial program 9.6%

        \[e^{x} - 1 \]
      2. Add Preprocessing
      3. Taylor expanded in x around 0

        \[\leadsto \color{blue}{x \cdot \left(1 + x \cdot \left(\frac{1}{2} + x \cdot \left(\frac{1}{6} + \frac{1}{24} \cdot x\right)\right)\right)} \]
      4. Step-by-step derivation
        1. *-commutativeN/A

          \[\leadsto \color{blue}{\left(1 + x \cdot \left(\frac{1}{2} + x \cdot \left(\frac{1}{6} + \frac{1}{24} \cdot x\right)\right)\right) \cdot x} \]
        2. lower-*.f64N/A

          \[\leadsto \color{blue}{\left(1 + x \cdot \left(\frac{1}{2} + x \cdot \left(\frac{1}{6} + \frac{1}{24} \cdot x\right)\right)\right) \cdot x} \]
        3. +-commutativeN/A

          \[\leadsto \color{blue}{\left(x \cdot \left(\frac{1}{2} + x \cdot \left(\frac{1}{6} + \frac{1}{24} \cdot x\right)\right) + 1\right)} \cdot x \]
        4. *-commutativeN/A

          \[\leadsto \left(\color{blue}{\left(\frac{1}{2} + x \cdot \left(\frac{1}{6} + \frac{1}{24} \cdot x\right)\right) \cdot x} + 1\right) \cdot x \]
        5. lower-fma.f64N/A

          \[\leadsto \color{blue}{\mathsf{fma}\left(\frac{1}{2} + x \cdot \left(\frac{1}{6} + \frac{1}{24} \cdot x\right), x, 1\right)} \cdot x \]
        6. +-commutativeN/A

          \[\leadsto \mathsf{fma}\left(\color{blue}{x \cdot \left(\frac{1}{6} + \frac{1}{24} \cdot x\right) + \frac{1}{2}}, x, 1\right) \cdot x \]
        7. *-commutativeN/A

          \[\leadsto \mathsf{fma}\left(\color{blue}{\left(\frac{1}{6} + \frac{1}{24} \cdot x\right) \cdot x} + \frac{1}{2}, x, 1\right) \cdot x \]
        8. lower-fma.f64N/A

          \[\leadsto \mathsf{fma}\left(\color{blue}{\mathsf{fma}\left(\frac{1}{6} + \frac{1}{24} \cdot x, x, \frac{1}{2}\right)}, x, 1\right) \cdot x \]
        9. +-commutativeN/A

          \[\leadsto \mathsf{fma}\left(\mathsf{fma}\left(\color{blue}{\frac{1}{24} \cdot x + \frac{1}{6}}, x, \frac{1}{2}\right), x, 1\right) \cdot x \]
        10. lower-fma.f6499.3

          \[\leadsto \mathsf{fma}\left(\mathsf{fma}\left(\color{blue}{\mathsf{fma}\left(0.041666666666666664, x, 0.16666666666666666\right)}, x, 0.5\right), x, 1\right) \cdot x \]
      5. Applied rewrites99.3%

        \[\leadsto \color{blue}{\mathsf{fma}\left(\mathsf{fma}\left(\mathsf{fma}\left(0.041666666666666664, x, 0.16666666666666666\right), x, 0.5\right), x, 1\right) \cdot x} \]
      6. Add Preprocessing

      Alternative 4: 99.3% accurate, 5.8× speedup?

      \[\begin{array}{l} \\ \mathsf{fma}\left(\mathsf{fma}\left(0.16666666666666666, x, 0.5\right) \cdot x, x, x\right) \end{array} \]
      (FPCore (x)
       :precision binary64
       (fma (* (fma 0.16666666666666666 x 0.5) x) x x))
      double code(double x) {
      	return fma((fma(0.16666666666666666, x, 0.5) * x), x, x);
      }
      
      function code(x)
      	return fma(Float64(fma(0.16666666666666666, x, 0.5) * x), x, x)
      end
      
      code[x_] := N[(N[(N[(0.16666666666666666 * x + 0.5), $MachinePrecision] * x), $MachinePrecision] * x + x), $MachinePrecision]
      
      \begin{array}{l}
      
      \\
      \mathsf{fma}\left(\mathsf{fma}\left(0.16666666666666666, x, 0.5\right) \cdot x, x, x\right)
      \end{array}
      
      Derivation
      1. Initial program 9.6%

        \[e^{x} - 1 \]
      2. Add Preprocessing
      3. Step-by-step derivation
        1. lift--.f64N/A

          \[\leadsto \color{blue}{e^{x} - 1} \]
        2. lift-exp.f64N/A

          \[\leadsto \color{blue}{e^{x}} - 1 \]
        3. lower-expm1.f64100.0

          \[\leadsto \color{blue}{\mathsf{expm1}\left(x\right)} \]
      4. Applied rewrites100.0%

        \[\leadsto \color{blue}{\mathsf{expm1}\left(x\right)} \]
      5. Taylor expanded in x around 0

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

          \[\leadsto x \cdot \color{blue}{\left(x \cdot \left(\frac{1}{2} + \frac{1}{6} \cdot x\right) + 1\right)} \]
        2. distribute-rgt-inN/A

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

          \[\leadsto \left(x \cdot \left(\frac{1}{2} + \frac{1}{6} \cdot x\right)\right) \cdot x + \color{blue}{x} \]
        4. lower-fma.f64N/A

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

          \[\leadsto \mathsf{fma}\left(\color{blue}{\left(\frac{1}{2} + \frac{1}{6} \cdot x\right) \cdot x}, x, x\right) \]
        6. lower-*.f64N/A

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

          \[\leadsto \mathsf{fma}\left(\color{blue}{\left(\frac{1}{6} \cdot x + \frac{1}{2}\right)} \cdot x, x, x\right) \]
        8. lower-fma.f6499.0

          \[\leadsto \mathsf{fma}\left(\color{blue}{\mathsf{fma}\left(0.16666666666666666, x, 0.5\right)} \cdot x, x, x\right) \]
      7. Applied rewrites99.0%

        \[\leadsto \color{blue}{\mathsf{fma}\left(\mathsf{fma}\left(0.16666666666666666, x, 0.5\right) \cdot x, x, x\right)} \]
      8. Add Preprocessing

      Alternative 5: 99.3% accurate, 5.8× speedup?

      \[\begin{array}{l} \\ \mathsf{fma}\left(\mathsf{fma}\left(0.16666666666666666, x, 0.5\right), x, 1\right) \cdot x \end{array} \]
      (FPCore (x)
       :precision binary64
       (* (fma (fma 0.16666666666666666 x 0.5) x 1.0) x))
      double code(double x) {
      	return fma(fma(0.16666666666666666, x, 0.5), x, 1.0) * x;
      }
      
      function code(x)
      	return Float64(fma(fma(0.16666666666666666, x, 0.5), x, 1.0) * x)
      end
      
      code[x_] := N[(N[(N[(0.16666666666666666 * x + 0.5), $MachinePrecision] * x + 1.0), $MachinePrecision] * x), $MachinePrecision]
      
      \begin{array}{l}
      
      \\
      \mathsf{fma}\left(\mathsf{fma}\left(0.16666666666666666, x, 0.5\right), x, 1\right) \cdot x
      \end{array}
      
      Derivation
      1. Initial program 9.6%

        \[e^{x} - 1 \]
      2. Add Preprocessing
      3. Taylor expanded in x around 0

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

          \[\leadsto \color{blue}{\left(1 + x \cdot \left(\frac{1}{2} + \frac{1}{6} \cdot x\right)\right) \cdot x} \]
        2. lower-*.f64N/A

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

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

          \[\leadsto \left(\color{blue}{\left(\frac{1}{2} + \frac{1}{6} \cdot x\right) \cdot x} + 1\right) \cdot x \]
        5. lower-fma.f64N/A

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

          \[\leadsto \mathsf{fma}\left(\color{blue}{\frac{1}{6} \cdot x + \frac{1}{2}}, x, 1\right) \cdot x \]
        7. lower-fma.f6499.0

          \[\leadsto \mathsf{fma}\left(\color{blue}{\mathsf{fma}\left(0.16666666666666666, x, 0.5\right)}, x, 1\right) \cdot x \]
      5. Applied rewrites99.0%

        \[\leadsto \color{blue}{\mathsf{fma}\left(\mathsf{fma}\left(0.16666666666666666, x, 0.5\right), x, 1\right) \cdot x} \]
      6. Add Preprocessing

      Alternative 6: 98.9% accurate, 8.7× speedup?

      \[\begin{array}{l} \\ \mathsf{fma}\left(0.5 \cdot x, x, x\right) \end{array} \]
      (FPCore (x) :precision binary64 (fma (* 0.5 x) x x))
      double code(double x) {
      	return fma((0.5 * x), x, x);
      }
      
      function code(x)
      	return fma(Float64(0.5 * x), x, x)
      end
      
      code[x_] := N[(N[(0.5 * x), $MachinePrecision] * x + x), $MachinePrecision]
      
      \begin{array}{l}
      
      \\
      \mathsf{fma}\left(0.5 \cdot x, x, x\right)
      \end{array}
      
      Derivation
      1. Initial program 9.6%

        \[e^{x} - 1 \]
      2. Add Preprocessing
      3. Taylor expanded in x around 0

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

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

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

          \[\leadsto \color{blue}{\left(\frac{1}{2} \cdot x + 1\right)} \cdot x \]
        4. lower-fma.f6498.4

          \[\leadsto \color{blue}{\mathsf{fma}\left(0.5, x, 1\right)} \cdot x \]
      5. Applied rewrites98.4%

        \[\leadsto \color{blue}{\mathsf{fma}\left(0.5, x, 1\right) \cdot x} \]
      6. Step-by-step derivation
        1. Applied rewrites98.4%

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

        Alternative 7: 98.9% accurate, 8.7× speedup?

        \[\begin{array}{l} \\ \mathsf{fma}\left(0.5, x, 1\right) \cdot x \end{array} \]
        (FPCore (x) :precision binary64 (* (fma 0.5 x 1.0) x))
        double code(double x) {
        	return fma(0.5, x, 1.0) * x;
        }
        
        function code(x)
        	return Float64(fma(0.5, x, 1.0) * x)
        end
        
        code[x_] := N[(N[(0.5 * x + 1.0), $MachinePrecision] * x), $MachinePrecision]
        
        \begin{array}{l}
        
        \\
        \mathsf{fma}\left(0.5, x, 1\right) \cdot x
        \end{array}
        
        Derivation
        1. Initial program 9.6%

          \[e^{x} - 1 \]
        2. Add Preprocessing
        3. Taylor expanded in x around 0

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

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

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

            \[\leadsto \color{blue}{\left(\frac{1}{2} \cdot x + 1\right)} \cdot x \]
          4. lower-fma.f6498.4

            \[\leadsto \color{blue}{\mathsf{fma}\left(0.5, x, 1\right)} \cdot x \]
        5. Applied rewrites98.4%

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

        Alternative 8: 97.8% accurate, 17.3× speedup?

        \[\begin{array}{l} \\ 1 \cdot x \end{array} \]
        (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}
        
        \\
        1 \cdot x
        \end{array}
        
        Derivation
        1. Initial program 9.6%

          \[e^{x} - 1 \]
        2. Add Preprocessing
        3. Taylor expanded in x around 0

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

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

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

            \[\leadsto \color{blue}{\left(\frac{1}{2} \cdot x + 1\right)} \cdot x \]
          4. lower-fma.f6498.4

            \[\leadsto \color{blue}{\mathsf{fma}\left(0.5, x, 1\right)} \cdot x \]
        5. Applied rewrites98.4%

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

          \[\leadsto \left(\frac{1}{2} \cdot x\right) \cdot x \]
        7. Step-by-step derivation
          1. Applied rewrites5.9%

            \[\leadsto \left(0.5 \cdot x\right) \cdot x \]
          2. Taylor expanded in x around 0

            \[\leadsto 1 \cdot x \]
          3. Step-by-step derivation
            1. Applied rewrites97.0%

              \[\leadsto 1 \cdot x \]
            2. Add Preprocessing

            Alternative 9: 5.4% accurate, 26.0× speedup?

            \[\begin{array}{l} \\ 1 - 1 \end{array} \]
            (FPCore (x) :precision binary64 (- 1.0 1.0))
            double code(double x) {
            	return 1.0 - 1.0;
            }
            
            real(8) function code(x)
                real(8), intent (in) :: x
                code = 1.0d0 - 1.0d0
            end function
            
            public static double code(double x) {
            	return 1.0 - 1.0;
            }
            
            def code(x):
            	return 1.0 - 1.0
            
            function code(x)
            	return Float64(1.0 - 1.0)
            end
            
            function tmp = code(x)
            	tmp = 1.0 - 1.0;
            end
            
            code[x_] := N[(1.0 - 1.0), $MachinePrecision]
            
            \begin{array}{l}
            
            \\
            1 - 1
            \end{array}
            
            Derivation
            1. Initial program 9.6%

              \[e^{x} - 1 \]
            2. Add Preprocessing
            3. Taylor expanded in x around 0

              \[\leadsto \color{blue}{1} - 1 \]
            4. Step-by-step derivation
              1. Applied rewrites5.4%

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

              Developer Target 1: 100.0% accurate, 1.0× speedup?

              \[\begin{array}{l} \\ \mathsf{expm1}\left(x\right) \end{array} \]
              (FPCore (x) :precision binary64 (expm1 x))
              double code(double x) {
              	return expm1(x);
              }
              
              public static double code(double x) {
              	return Math.expm1(x);
              }
              
              def code(x):
              	return math.expm1(x)
              
              function code(x)
              	return expm1(x)
              end
              
              code[x_] := N[(Exp[x] - 1), $MachinePrecision]
              
              \begin{array}{l}
              
              \\
              \mathsf{expm1}\left(x\right)
              \end{array}
              

              Reproduce

              ?
              herbie shell --seed 2024296 
              (FPCore (x)
                :name "expm1 (example 3.7)"
                :precision binary64
                :pre (<= (fabs x) 1.0)
              
                :alt
                (! :herbie-platform default (expm1 x))
              
                (- (exp x) 1.0))