Numeric.SpecFunctions:log1p from math-functions-0.1.5.2, A

Percentage Accurate: 99.9% → 99.9%
Time: 8.6s
Alternatives: 3
Speedup: 1.0×

Specification

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

\\
x \cdot \left(1 - x \cdot y\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 3 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: 99.9% accurate, 1.0× speedup?

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

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

Alternative 1: 99.9% accurate, 1.0× speedup?

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

\\
x \cdot \left(1 - x \cdot y\right)
\end{array}
Derivation
  1. Initial program 99.9%

    \[x \cdot \left(1 - x \cdot y\right) \]
  2. Add Preprocessing
  3. Add Preprocessing

Alternative 2: 82.6% accurate, 0.3× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := x \cdot \left(1 - x \cdot y\right)\\ t_1 := x \cdot \left(y \cdot \left(-x\right)\right)\\ \mathbf{if}\;t\_0 \leq -5 \cdot 10^{+69}:\\ \;\;\;\;t\_1\\ \mathbf{elif}\;t\_0 \leq 10^{+84}:\\ \;\;\;\;-\left(-x\right)\\ \mathbf{else}:\\ \;\;\;\;t\_1\\ \end{array} \end{array} \]
(FPCore (x y)
 :precision binary64
 (let* ((t_0 (* x (- 1.0 (* x y)))) (t_1 (* x (* y (- x)))))
   (if (<= t_0 -5e+69) t_1 (if (<= t_0 1e+84) (- (- x)) t_1))))
double code(double x, double y) {
	double t_0 = x * (1.0 - (x * y));
	double t_1 = x * (y * -x);
	double tmp;
	if (t_0 <= -5e+69) {
		tmp = t_1;
	} else if (t_0 <= 1e+84) {
		tmp = -(-x);
	} else {
		tmp = t_1;
	}
	return tmp;
}
real(8) function code(x, y)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8) :: t_0
    real(8) :: t_1
    real(8) :: tmp
    t_0 = x * (1.0d0 - (x * y))
    t_1 = x * (y * -x)
    if (t_0 <= (-5d+69)) then
        tmp = t_1
    else if (t_0 <= 1d+84) then
        tmp = -(-x)
    else
        tmp = t_1
    end if
    code = tmp
end function
public static double code(double x, double y) {
	double t_0 = x * (1.0 - (x * y));
	double t_1 = x * (y * -x);
	double tmp;
	if (t_0 <= -5e+69) {
		tmp = t_1;
	} else if (t_0 <= 1e+84) {
		tmp = -(-x);
	} else {
		tmp = t_1;
	}
	return tmp;
}
def code(x, y):
	t_0 = x * (1.0 - (x * y))
	t_1 = x * (y * -x)
	tmp = 0
	if t_0 <= -5e+69:
		tmp = t_1
	elif t_0 <= 1e+84:
		tmp = -(-x)
	else:
		tmp = t_1
	return tmp
function code(x, y)
	t_0 = Float64(x * Float64(1.0 - Float64(x * y)))
	t_1 = Float64(x * Float64(y * Float64(-x)))
	tmp = 0.0
	if (t_0 <= -5e+69)
		tmp = t_1;
	elseif (t_0 <= 1e+84)
		tmp = Float64(-Float64(-x));
	else
		tmp = t_1;
	end
	return tmp
end
function tmp_2 = code(x, y)
	t_0 = x * (1.0 - (x * y));
	t_1 = x * (y * -x);
	tmp = 0.0;
	if (t_0 <= -5e+69)
		tmp = t_1;
	elseif (t_0 <= 1e+84)
		tmp = -(-x);
	else
		tmp = t_1;
	end
	tmp_2 = tmp;
end
code[x_, y_] := Block[{t$95$0 = N[(x * N[(1.0 - N[(x * y), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]}, Block[{t$95$1 = N[(x * N[(y * (-x)), $MachinePrecision]), $MachinePrecision]}, If[LessEqual[t$95$0, -5e+69], t$95$1, If[LessEqual[t$95$0, 1e+84], (-(-x)), t$95$1]]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := x \cdot \left(1 - x \cdot y\right)\\
t_1 := x \cdot \left(y \cdot \left(-x\right)\right)\\
\mathbf{if}\;t\_0 \leq -5 \cdot 10^{+69}:\\
\;\;\;\;t\_1\\

\mathbf{elif}\;t\_0 \leq 10^{+84}:\\
\;\;\;\;-\left(-x\right)\\

\mathbf{else}:\\
\;\;\;\;t\_1\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (*.f64 x (-.f64 #s(literal 1 binary64) (*.f64 x y))) < -5.00000000000000036e69 or 1.00000000000000006e84 < (*.f64 x (-.f64 #s(literal 1 binary64) (*.f64 x y)))

    1. Initial program 99.8%

      \[x \cdot \left(1 - x \cdot y\right) \]
    2. Add Preprocessing
    3. Taylor expanded in x around inf

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

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

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

        \[\leadsto x \cdot \color{blue}{\left(y \cdot \left(-1 \cdot x\right)\right)} \]
      4. mul-1-negN/A

        \[\leadsto x \cdot \left(y \cdot \color{blue}{\left(\mathsf{neg}\left(x\right)\right)}\right) \]
      5. lower-neg.f6490.2

        \[\leadsto x \cdot \left(y \cdot \color{blue}{\left(-x\right)}\right) \]
    5. Applied rewrites90.2%

      \[\leadsto x \cdot \color{blue}{\left(y \cdot \left(-x\right)\right)} \]

    if -5.00000000000000036e69 < (*.f64 x (-.f64 #s(literal 1 binary64) (*.f64 x y))) < 1.00000000000000006e84

    1. Initial program 99.9%

      \[x \cdot \left(1 - x \cdot y\right) \]
    2. Add Preprocessing
    3. Applied rewrites83.4%

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

      \[\leadsto \frac{\mathsf{neg}\left(x \cdot \color{blue}{\left({x}^{2} \cdot {y}^{2}\right)}\right)}{\mathsf{fma}\left(x, y, -1\right)} \]
    5. Step-by-step derivation
      1. unpow2N/A

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

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

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

        \[\leadsto \frac{\mathsf{neg}\left(x \cdot \left(x \cdot \color{blue}{\left(x \cdot {y}^{2}\right)}\right)\right)}{\mathsf{fma}\left(x, y, -1\right)} \]
      5. unpow2N/A

        \[\leadsto \frac{\mathsf{neg}\left(x \cdot \left(x \cdot \left(x \cdot \color{blue}{\left(y \cdot y\right)}\right)\right)\right)}{\mathsf{fma}\left(x, y, -1\right)} \]
      6. lower-*.f647.3

        \[\leadsto \frac{-x \cdot \left(x \cdot \left(x \cdot \color{blue}{\left(y \cdot y\right)}\right)\right)}{\mathsf{fma}\left(x, y, -1\right)} \]
    6. Applied rewrites7.3%

      \[\leadsto \frac{-x \cdot \color{blue}{\left(x \cdot \left(x \cdot \left(y \cdot y\right)\right)\right)}}{\mathsf{fma}\left(x, y, -1\right)} \]
    7. Step-by-step derivation
      1. lift-/.f64N/A

        \[\leadsto \color{blue}{\frac{\mathsf{neg}\left(x \cdot \left(x \cdot \left(x \cdot \left(y \cdot y\right)\right)\right)\right)}{\mathsf{fma}\left(x, y, -1\right)}} \]
      2. lift-neg.f64N/A

        \[\leadsto \frac{\color{blue}{\mathsf{neg}\left(x \cdot \left(x \cdot \left(x \cdot \left(y \cdot y\right)\right)\right)\right)}}{\mathsf{fma}\left(x, y, -1\right)} \]
      3. distribute-frac-negN/A

        \[\leadsto \color{blue}{\mathsf{neg}\left(\frac{x \cdot \left(x \cdot \left(x \cdot \left(y \cdot y\right)\right)\right)}{\mathsf{fma}\left(x, y, -1\right)}\right)} \]
      4. lower-neg.f64N/A

        \[\leadsto \color{blue}{\mathsf{neg}\left(\frac{x \cdot \left(x \cdot \left(x \cdot \left(y \cdot y\right)\right)\right)}{\mathsf{fma}\left(x, y, -1\right)}\right)} \]
      5. lift-*.f64N/A

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

        \[\leadsto \mathsf{neg}\left(\frac{\color{blue}{\left(x \cdot \left(x \cdot \left(y \cdot y\right)\right)\right) \cdot x}}{\mathsf{fma}\left(x, y, -1\right)}\right) \]
      7. associate-/l*N/A

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

        \[\leadsto \mathsf{neg}\left(\color{blue}{\left(x \cdot \left(x \cdot \left(y \cdot y\right)\right)\right) \cdot \frac{x}{\mathsf{fma}\left(x, y, -1\right)}}\right) \]
    8. Applied rewrites17.7%

      \[\leadsto \color{blue}{-\left(y \cdot \left(x \cdot \left(x \cdot y\right)\right)\right) \cdot \frac{x}{\mathsf{fma}\left(x, y, -1\right)}} \]
    9. Taylor expanded in x around 0

      \[\leadsto \mathsf{neg}\left(\color{blue}{-1 \cdot x}\right) \]
    10. Step-by-step derivation
      1. mul-1-negN/A

        \[\leadsto \mathsf{neg}\left(\color{blue}{\left(\mathsf{neg}\left(x\right)\right)}\right) \]
      2. lower-neg.f6483.8

        \[\leadsto -\color{blue}{\left(-x\right)} \]
    11. Applied rewrites83.8%

      \[\leadsto -\color{blue}{\left(-x\right)} \]
  3. Recombined 2 regimes into one program.
  4. Add Preprocessing

Alternative 3: 51.2% accurate, 2.8× speedup?

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

\\
-\left(-x\right)
\end{array}
Derivation
  1. Initial program 99.9%

    \[x \cdot \left(1 - x \cdot y\right) \]
  2. Add Preprocessing
  3. Applied rewrites67.3%

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

    \[\leadsto \frac{\mathsf{neg}\left(x \cdot \color{blue}{\left({x}^{2} \cdot {y}^{2}\right)}\right)}{\mathsf{fma}\left(x, y, -1\right)} \]
  5. Step-by-step derivation
    1. unpow2N/A

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

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

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

      \[\leadsto \frac{\mathsf{neg}\left(x \cdot \left(x \cdot \color{blue}{\left(x \cdot {y}^{2}\right)}\right)\right)}{\mathsf{fma}\left(x, y, -1\right)} \]
    5. unpow2N/A

      \[\leadsto \frac{\mathsf{neg}\left(x \cdot \left(x \cdot \left(x \cdot \color{blue}{\left(y \cdot y\right)}\right)\right)\right)}{\mathsf{fma}\left(x, y, -1\right)} \]
    6. lower-*.f6422.6

      \[\leadsto \frac{-x \cdot \left(x \cdot \left(x \cdot \color{blue}{\left(y \cdot y\right)}\right)\right)}{\mathsf{fma}\left(x, y, -1\right)} \]
  6. Applied rewrites22.6%

    \[\leadsto \frac{-x \cdot \color{blue}{\left(x \cdot \left(x \cdot \left(y \cdot y\right)\right)\right)}}{\mathsf{fma}\left(x, y, -1\right)} \]
  7. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{\mathsf{neg}\left(x \cdot \left(x \cdot \left(x \cdot \left(y \cdot y\right)\right)\right)\right)}{\mathsf{fma}\left(x, y, -1\right)}} \]
    2. lift-neg.f64N/A

      \[\leadsto \frac{\color{blue}{\mathsf{neg}\left(x \cdot \left(x \cdot \left(x \cdot \left(y \cdot y\right)\right)\right)\right)}}{\mathsf{fma}\left(x, y, -1\right)} \]
    3. distribute-frac-negN/A

      \[\leadsto \color{blue}{\mathsf{neg}\left(\frac{x \cdot \left(x \cdot \left(x \cdot \left(y \cdot y\right)\right)\right)}{\mathsf{fma}\left(x, y, -1\right)}\right)} \]
    4. lower-neg.f64N/A

      \[\leadsto \color{blue}{\mathsf{neg}\left(\frac{x \cdot \left(x \cdot \left(x \cdot \left(y \cdot y\right)\right)\right)}{\mathsf{fma}\left(x, y, -1\right)}\right)} \]
    5. lift-*.f64N/A

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

      \[\leadsto \mathsf{neg}\left(\frac{\color{blue}{\left(x \cdot \left(x \cdot \left(y \cdot y\right)\right)\right) \cdot x}}{\mathsf{fma}\left(x, y, -1\right)}\right) \]
    7. associate-/l*N/A

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

      \[\leadsto \mathsf{neg}\left(\color{blue}{\left(x \cdot \left(x \cdot \left(y \cdot y\right)\right)\right) \cdot \frac{x}{\mathsf{fma}\left(x, y, -1\right)}}\right) \]
  8. Applied rewrites33.8%

    \[\leadsto \color{blue}{-\left(y \cdot \left(x \cdot \left(x \cdot y\right)\right)\right) \cdot \frac{x}{\mathsf{fma}\left(x, y, -1\right)}} \]
  9. Taylor expanded in x around 0

    \[\leadsto \mathsf{neg}\left(\color{blue}{-1 \cdot x}\right) \]
  10. Step-by-step derivation
    1. mul-1-negN/A

      \[\leadsto \mathsf{neg}\left(\color{blue}{\left(\mathsf{neg}\left(x\right)\right)}\right) \]
    2. lower-neg.f6450.2

      \[\leadsto -\color{blue}{\left(-x\right)} \]
  11. Applied rewrites50.2%

    \[\leadsto -\color{blue}{\left(-x\right)} \]
  12. Add Preprocessing

Reproduce

?
herbie shell --seed 2024234 
(FPCore (x y)
  :name "Numeric.SpecFunctions:log1p from math-functions-0.1.5.2, A"
  :precision binary64
  (* x (- 1.0 (* x y))))