Numeric.Log:$cexpm1 from log-domain-0.10.2.1, B

Percentage Accurate: 100.0% → 100.0%
Time: 6.0s
Alternatives: 5
Speedup: 1.2×

Specification

?
\[\begin{array}{l} \\ \left(x \cdot y + x\right) + y \end{array} \]
(FPCore (x y) :precision binary64 (+ (+ (* x y) x) y))
double code(double x, double y) {
	return ((x * y) + x) + y;
}
real(8) function code(x, y)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    code = ((x * y) + x) + y
end function
public static double code(double x, double y) {
	return ((x * y) + x) + y;
}
def code(x, y):
	return ((x * y) + x) + y
function code(x, y)
	return Float64(Float64(Float64(x * y) + x) + y)
end
function tmp = code(x, y)
	tmp = ((x * y) + x) + y;
end
code[x_, y_] := N[(N[(N[(x * y), $MachinePrecision] + x), $MachinePrecision] + y), $MachinePrecision]
\begin{array}{l}

\\
\left(x \cdot y + x\right) + y
\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 5 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?

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

\\
\left(x \cdot y + x\right) + y
\end{array}

Alternative 1: 100.0% accurate, 1.2× speedup?

\[\begin{array}{l} [x, y] = \mathsf{sort}([x, y])\\ \\ \mathsf{fma}\left(y + 1, x, y\right) \end{array} \]
NOTE: x and y should be sorted in increasing order before calling this function.
(FPCore (x y) :precision binary64 (fma (+ y 1.0) x y))
assert(x < y);
double code(double x, double y) {
	return fma((y + 1.0), x, y);
}
x, y = sort([x, y])
function code(x, y)
	return fma(Float64(y + 1.0), x, y)
end
NOTE: x and y should be sorted in increasing order before calling this function.
code[x_, y_] := N[(N[(y + 1.0), $MachinePrecision] * x + y), $MachinePrecision]
\begin{array}{l}
[x, y] = \mathsf{sort}([x, y])\\
\\
\mathsf{fma}\left(y + 1, x, y\right)
\end{array}
Derivation
  1. Initial program 100.0%

    \[\left(x \cdot y + x\right) + y \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-+.f64N/A

      \[\leadsto \color{blue}{\left(x \cdot y + x\right) + y} \]
    2. lift-+.f64N/A

      \[\leadsto \color{blue}{\left(x \cdot y + x\right)} + y \]
    3. lift-*.f64N/A

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

      \[\leadsto \left(\color{blue}{y \cdot x} + x\right) + y \]
    5. distribute-lft1-inN/A

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

      \[\leadsto \color{blue}{\mathsf{fma}\left(y + 1, x, y\right)} \]
    7. lower-+.f64100.0

      \[\leadsto \mathsf{fma}\left(\color{blue}{y + 1}, x, y\right) \]
  4. Applied rewrites100.0%

    \[\leadsto \color{blue}{\mathsf{fma}\left(y + 1, x, y\right)} \]
  5. Add Preprocessing

Alternative 2: 64.9% accurate, 0.3× speedup?

\[\begin{array}{l} [x, y] = \mathsf{sort}([x, y])\\ \\ \begin{array}{l} t_0 := y + \left(x + y \cdot x\right)\\ \mathbf{if}\;t\_0 \leq -1 \cdot 10^{-268}:\\ \;\;\;\;\mathsf{fma}\left(x, y, x\right)\\ \mathbf{elif}\;t\_0 \leq 5 \cdot 10^{+176}:\\ \;\;\;\;y \cdot 2\\ \mathbf{else}:\\ \;\;\;\;\mathsf{fma}\left(x, y, x\right)\\ \end{array} \end{array} \]
NOTE: x and y should be sorted in increasing order before calling this function.
(FPCore (x y)
 :precision binary64
 (let* ((t_0 (+ y (+ x (* y x)))))
   (if (<= t_0 -1e-268)
     (fma x y x)
     (if (<= t_0 5e+176) (* y 2.0) (fma x y x)))))
assert(x < y);
double code(double x, double y) {
	double t_0 = y + (x + (y * x));
	double tmp;
	if (t_0 <= -1e-268) {
		tmp = fma(x, y, x);
	} else if (t_0 <= 5e+176) {
		tmp = y * 2.0;
	} else {
		tmp = fma(x, y, x);
	}
	return tmp;
}
x, y = sort([x, y])
function code(x, y)
	t_0 = Float64(y + Float64(x + Float64(y * x)))
	tmp = 0.0
	if (t_0 <= -1e-268)
		tmp = fma(x, y, x);
	elseif (t_0 <= 5e+176)
		tmp = Float64(y * 2.0);
	else
		tmp = fma(x, y, x);
	end
	return tmp
end
NOTE: x and y should be sorted in increasing order before calling this function.
code[x_, y_] := Block[{t$95$0 = N[(y + N[(x + N[(y * x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]}, If[LessEqual[t$95$0, -1e-268], N[(x * y + x), $MachinePrecision], If[LessEqual[t$95$0, 5e+176], N[(y * 2.0), $MachinePrecision], N[(x * y + x), $MachinePrecision]]]]
\begin{array}{l}
[x, y] = \mathsf{sort}([x, y])\\
\\
\begin{array}{l}
t_0 := y + \left(x + y \cdot x\right)\\
\mathbf{if}\;t\_0 \leq -1 \cdot 10^{-268}:\\
\;\;\;\;\mathsf{fma}\left(x, y, x\right)\\

\mathbf{elif}\;t\_0 \leq 5 \cdot 10^{+176}:\\
\;\;\;\;y \cdot 2\\

\mathbf{else}:\\
\;\;\;\;\mathsf{fma}\left(x, y, x\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (+.f64 (+.f64 (*.f64 x y) x) y) < -9.99999999999999958e-269 or 5e176 < (+.f64 (+.f64 (*.f64 x y) x) y)

    1. Initial program 100.0%

      \[\left(x \cdot y + x\right) + y \]
    2. Add Preprocessing
    3. Taylor expanded in x around inf

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

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

        \[\leadsto \color{blue}{x \cdot y + x \cdot 1} \]
      3. *-rgt-identityN/A

        \[\leadsto x \cdot y + \color{blue}{x} \]
      4. lower-fma.f6474.2

        \[\leadsto \color{blue}{\mathsf{fma}\left(x, y, x\right)} \]
    5. Applied rewrites74.2%

      \[\leadsto \color{blue}{\mathsf{fma}\left(x, y, x\right)} \]

    if -9.99999999999999958e-269 < (+.f64 (+.f64 (*.f64 x y) x) y) < 5e176

    1. Initial program 100.0%

      \[\left(x \cdot y + x\right) + y \]
    2. Add Preprocessing
    3. Step-by-step derivation
      1. lift-+.f64N/A

        \[\leadsto \color{blue}{\left(x \cdot y + x\right) + y} \]
      2. lift-+.f64N/A

        \[\leadsto \color{blue}{\left(x \cdot y + x\right)} + y \]
      3. lift-*.f64N/A

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

        \[\leadsto \left(\color{blue}{y \cdot x} + x\right) + y \]
      5. distribute-lft1-inN/A

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

        \[\leadsto \color{blue}{\mathsf{fma}\left(y + 1, x, y\right)} \]
      7. lower-+.f64100.0

        \[\leadsto \mathsf{fma}\left(\color{blue}{y + 1}, x, y\right) \]
    4. Applied rewrites100.0%

      \[\leadsto \color{blue}{\mathsf{fma}\left(y + 1, x, y\right)} \]
    5. Taylor expanded in y around -inf

      \[\leadsto \color{blue}{2 \cdot y} \]
    6. Step-by-step derivation
      1. *-commutativeN/A

        \[\leadsto \color{blue}{y \cdot 2} \]
      2. lower-*.f6411.9

        \[\leadsto \color{blue}{y \cdot 2} \]
    7. Applied rewrites11.9%

      \[\leadsto \color{blue}{y \cdot 2} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification54.2%

    \[\leadsto \begin{array}{l} \mathbf{if}\;y + \left(x + y \cdot x\right) \leq -1 \cdot 10^{-268}:\\ \;\;\;\;\mathsf{fma}\left(x, y, x\right)\\ \mathbf{elif}\;y + \left(x + y \cdot x\right) \leq 5 \cdot 10^{+176}:\\ \;\;\;\;y \cdot 2\\ \mathbf{else}:\\ \;\;\;\;\mathsf{fma}\left(x, y, x\right)\\ \end{array} \]
  5. Add Preprocessing

Alternative 3: 98.4% accurate, 0.5× speedup?

\[\begin{array}{l} [x, y] = \mathsf{sort}([x, y])\\ \\ \begin{array}{l} \mathbf{if}\;y + \left(x + y \cdot x\right) \leq -1 \cdot 10^{-268}:\\ \;\;\;\;\mathsf{fma}\left(x, y, x\right)\\ \mathbf{else}:\\ \;\;\;\;\mathsf{fma}\left(x, y, y\right)\\ \end{array} \end{array} \]
NOTE: x and y should be sorted in increasing order before calling this function.
(FPCore (x y)
 :precision binary64
 (if (<= (+ y (+ x (* y x))) -1e-268) (fma x y x) (fma x y y)))
assert(x < y);
double code(double x, double y) {
	double tmp;
	if ((y + (x + (y * x))) <= -1e-268) {
		tmp = fma(x, y, x);
	} else {
		tmp = fma(x, y, y);
	}
	return tmp;
}
x, y = sort([x, y])
function code(x, y)
	tmp = 0.0
	if (Float64(y + Float64(x + Float64(y * x))) <= -1e-268)
		tmp = fma(x, y, x);
	else
		tmp = fma(x, y, y);
	end
	return tmp
end
NOTE: x and y should be sorted in increasing order before calling this function.
code[x_, y_] := If[LessEqual[N[(y + N[(x + N[(y * x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], -1e-268], N[(x * y + x), $MachinePrecision], N[(x * y + y), $MachinePrecision]]
\begin{array}{l}
[x, y] = \mathsf{sort}([x, y])\\
\\
\begin{array}{l}
\mathbf{if}\;y + \left(x + y \cdot x\right) \leq -1 \cdot 10^{-268}:\\
\;\;\;\;\mathsf{fma}\left(x, y, x\right)\\

\mathbf{else}:\\
\;\;\;\;\mathsf{fma}\left(x, y, y\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (+.f64 (+.f64 (*.f64 x y) x) y) < -9.99999999999999958e-269

    1. Initial program 100.0%

      \[\left(x \cdot y + x\right) + y \]
    2. Add Preprocessing
    3. Taylor expanded in x around inf

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

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

        \[\leadsto \color{blue}{x \cdot y + x \cdot 1} \]
      3. *-rgt-identityN/A

        \[\leadsto x \cdot y + \color{blue}{x} \]
      4. lower-fma.f6472.6

        \[\leadsto \color{blue}{\mathsf{fma}\left(x, y, x\right)} \]
    5. Applied rewrites72.6%

      \[\leadsto \color{blue}{\mathsf{fma}\left(x, y, x\right)} \]

    if -9.99999999999999958e-269 < (+.f64 (+.f64 (*.f64 x y) x) y)

    1. Initial program 100.0%

      \[\left(x \cdot y + x\right) + y \]
    2. Add Preprocessing
    3. Taylor expanded in y around inf

      \[\leadsto \color{blue}{y \cdot \left(1 + x\right)} \]
    4. Step-by-step derivation
      1. distribute-rgt-inN/A

        \[\leadsto \color{blue}{1 \cdot y + x \cdot y} \]
      2. *-lft-identityN/A

        \[\leadsto \color{blue}{y} + x \cdot y \]
      3. +-commutativeN/A

        \[\leadsto \color{blue}{x \cdot y + y} \]
      4. lower-fma.f6464.5

        \[\leadsto \color{blue}{\mathsf{fma}\left(x, y, y\right)} \]
    5. Applied rewrites64.5%

      \[\leadsto \color{blue}{\mathsf{fma}\left(x, y, y\right)} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification68.4%

    \[\leadsto \begin{array}{l} \mathbf{if}\;y + \left(x + y \cdot x\right) \leq -1 \cdot 10^{-268}:\\ \;\;\;\;\mathsf{fma}\left(x, y, x\right)\\ \mathbf{else}:\\ \;\;\;\;\mathsf{fma}\left(x, y, y\right)\\ \end{array} \]
  5. Add Preprocessing

Alternative 4: 32.7% accurate, 0.7× speedup?

\[\begin{array}{l} [x, y] = \mathsf{sort}([x, y])\\ \\ \begin{array}{l} \mathbf{if}\;x \leq -12000:\\ \;\;\;\;y \cdot x\\ \mathbf{elif}\;x \leq 2:\\ \;\;\;\;y \cdot 2\\ \mathbf{else}:\\ \;\;\;\;y \cdot x\\ \end{array} \end{array} \]
NOTE: x and y should be sorted in increasing order before calling this function.
(FPCore (x y)
 :precision binary64
 (if (<= x -12000.0) (* y x) (if (<= x 2.0) (* y 2.0) (* y x))))
assert(x < y);
double code(double x, double y) {
	double tmp;
	if (x <= -12000.0) {
		tmp = y * x;
	} else if (x <= 2.0) {
		tmp = y * 2.0;
	} else {
		tmp = y * x;
	}
	return tmp;
}
NOTE: x and y should be sorted in increasing order before calling this function.
real(8) function code(x, y)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8) :: tmp
    if (x <= (-12000.0d0)) then
        tmp = y * x
    else if (x <= 2.0d0) then
        tmp = y * 2.0d0
    else
        tmp = y * x
    end if
    code = tmp
end function
assert x < y;
public static double code(double x, double y) {
	double tmp;
	if (x <= -12000.0) {
		tmp = y * x;
	} else if (x <= 2.0) {
		tmp = y * 2.0;
	} else {
		tmp = y * x;
	}
	return tmp;
}
[x, y] = sort([x, y])
def code(x, y):
	tmp = 0
	if x <= -12000.0:
		tmp = y * x
	elif x <= 2.0:
		tmp = y * 2.0
	else:
		tmp = y * x
	return tmp
x, y = sort([x, y])
function code(x, y)
	tmp = 0.0
	if (x <= -12000.0)
		tmp = Float64(y * x);
	elseif (x <= 2.0)
		tmp = Float64(y * 2.0);
	else
		tmp = Float64(y * x);
	end
	return tmp
end
x, y = num2cell(sort([x, y])){:}
function tmp_2 = code(x, y)
	tmp = 0.0;
	if (x <= -12000.0)
		tmp = y * x;
	elseif (x <= 2.0)
		tmp = y * 2.0;
	else
		tmp = y * x;
	end
	tmp_2 = tmp;
end
NOTE: x and y should be sorted in increasing order before calling this function.
code[x_, y_] := If[LessEqual[x, -12000.0], N[(y * x), $MachinePrecision], If[LessEqual[x, 2.0], N[(y * 2.0), $MachinePrecision], N[(y * x), $MachinePrecision]]]
\begin{array}{l}
[x, y] = \mathsf{sort}([x, y])\\
\\
\begin{array}{l}
\mathbf{if}\;x \leq -12000:\\
\;\;\;\;y \cdot x\\

\mathbf{elif}\;x \leq 2:\\
\;\;\;\;y \cdot 2\\

\mathbf{else}:\\
\;\;\;\;y \cdot x\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < -12000 or 2 < x

    1. Initial program 100.0%

      \[\left(x \cdot y + x\right) + y \]
    2. Add Preprocessing
    3. Taylor expanded in y around inf

      \[\leadsto \color{blue}{y \cdot \left(1 + x\right)} \]
    4. Step-by-step derivation
      1. distribute-rgt-inN/A

        \[\leadsto \color{blue}{1 \cdot y + x \cdot y} \]
      2. *-lft-identityN/A

        \[\leadsto \color{blue}{y} + x \cdot y \]
      3. +-commutativeN/A

        \[\leadsto \color{blue}{x \cdot y + y} \]
      4. lower-fma.f6448.9

        \[\leadsto \color{blue}{\mathsf{fma}\left(x, y, y\right)} \]
    5. Applied rewrites48.9%

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

      \[\leadsto x \cdot \color{blue}{y} \]
    7. Step-by-step derivation
      1. Applied rewrites47.7%

        \[\leadsto y \cdot \color{blue}{x} \]

      if -12000 < x < 2

      1. Initial program 100.0%

        \[\left(x \cdot y + x\right) + y \]
      2. Add Preprocessing
      3. Step-by-step derivation
        1. lift-+.f64N/A

          \[\leadsto \color{blue}{\left(x \cdot y + x\right) + y} \]
        2. lift-+.f64N/A

          \[\leadsto \color{blue}{\left(x \cdot y + x\right)} + y \]
        3. lift-*.f64N/A

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

          \[\leadsto \left(\color{blue}{y \cdot x} + x\right) + y \]
        5. distribute-lft1-inN/A

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

          \[\leadsto \color{blue}{\mathsf{fma}\left(y + 1, x, y\right)} \]
        7. lower-+.f64100.0

          \[\leadsto \mathsf{fma}\left(\color{blue}{y + 1}, x, y\right) \]
      4. Applied rewrites100.0%

        \[\leadsto \color{blue}{\mathsf{fma}\left(y + 1, x, y\right)} \]
      5. Taylor expanded in y around -inf

        \[\leadsto \color{blue}{2 \cdot y} \]
      6. Step-by-step derivation
        1. *-commutativeN/A

          \[\leadsto \color{blue}{y \cdot 2} \]
        2. lower-*.f6415.0

          \[\leadsto \color{blue}{y \cdot 2} \]
      7. Applied rewrites15.0%

        \[\leadsto \color{blue}{y \cdot 2} \]
    8. Recombined 2 regimes into one program.
    9. Add Preprocessing

    Alternative 5: 8.9% accurate, 2.0× speedup?

    \[\begin{array}{l} [x, y] = \mathsf{sort}([x, y])\\ \\ y \cdot 2 \end{array} \]
    NOTE: x and y should be sorted in increasing order before calling this function.
    (FPCore (x y) :precision binary64 (* y 2.0))
    assert(x < y);
    double code(double x, double y) {
    	return y * 2.0;
    }
    
    NOTE: x and y should be sorted in increasing order before calling this function.
    real(8) function code(x, y)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        code = y * 2.0d0
    end function
    
    assert x < y;
    public static double code(double x, double y) {
    	return y * 2.0;
    }
    
    [x, y] = sort([x, y])
    def code(x, y):
    	return y * 2.0
    
    x, y = sort([x, y])
    function code(x, y)
    	return Float64(y * 2.0)
    end
    
    x, y = num2cell(sort([x, y])){:}
    function tmp = code(x, y)
    	tmp = y * 2.0;
    end
    
    NOTE: x and y should be sorted in increasing order before calling this function.
    code[x_, y_] := N[(y * 2.0), $MachinePrecision]
    
    \begin{array}{l}
    [x, y] = \mathsf{sort}([x, y])\\
    \\
    y \cdot 2
    \end{array}
    
    Derivation
    1. Initial program 100.0%

      \[\left(x \cdot y + x\right) + y \]
    2. Add Preprocessing
    3. Step-by-step derivation
      1. lift-+.f64N/A

        \[\leadsto \color{blue}{\left(x \cdot y + x\right) + y} \]
      2. lift-+.f64N/A

        \[\leadsto \color{blue}{\left(x \cdot y + x\right)} + y \]
      3. lift-*.f64N/A

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

        \[\leadsto \left(\color{blue}{y \cdot x} + x\right) + y \]
      5. distribute-lft1-inN/A

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

        \[\leadsto \color{blue}{\mathsf{fma}\left(y + 1, x, y\right)} \]
      7. lower-+.f64100.0

        \[\leadsto \mathsf{fma}\left(\color{blue}{y + 1}, x, y\right) \]
    4. Applied rewrites100.0%

      \[\leadsto \color{blue}{\mathsf{fma}\left(y + 1, x, y\right)} \]
    5. Taylor expanded in y around -inf

      \[\leadsto \color{blue}{2 \cdot y} \]
    6. Step-by-step derivation
      1. *-commutativeN/A

        \[\leadsto \color{blue}{y \cdot 2} \]
      2. lower-*.f648.8

        \[\leadsto \color{blue}{y \cdot 2} \]
    7. Applied rewrites8.8%

      \[\leadsto \color{blue}{y \cdot 2} \]
    8. Add Preprocessing

    Reproduce

    ?
    herbie shell --seed 2024223 
    (FPCore (x y)
      :name "Numeric.Log:$cexpm1 from log-domain-0.10.2.1, B"
      :precision binary64
      (+ (+ (* x y) x) y))