Numeric.AD.Rank1.Halley:findZero from ad-4.2.4

Percentage Accurate: 82.0% → 98.4%
Time: 10.4s
Alternatives: 4
Speedup: 1.1×

Specification

?
\[\begin{array}{l} \\ x - \frac{\left(y \cdot 2\right) \cdot z}{\left(z \cdot 2\right) \cdot z - y \cdot t} \end{array} \]
(FPCore (x y z t)
 :precision binary64
 (- x (/ (* (* y 2.0) z) (- (* (* z 2.0) z) (* y t)))))
double code(double x, double y, double z, double t) {
	return x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t)));
}
real(8) function code(x, y, z, t)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    real(8), intent (in) :: t
    code = x - (((y * 2.0d0) * z) / (((z * 2.0d0) * z) - (y * t)))
end function
public static double code(double x, double y, double z, double t) {
	return x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t)));
}
def code(x, y, z, t):
	return x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t)))
function code(x, y, z, t)
	return Float64(x - Float64(Float64(Float64(y * 2.0) * z) / Float64(Float64(Float64(z * 2.0) * z) - Float64(y * t))))
end
function tmp = code(x, y, z, t)
	tmp = x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t)));
end
code[x_, y_, z_, t_] := N[(x - N[(N[(N[(y * 2.0), $MachinePrecision] * z), $MachinePrecision] / N[(N[(N[(z * 2.0), $MachinePrecision] * z), $MachinePrecision] - N[(y * t), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
x - \frac{\left(y \cdot 2\right) \cdot z}{\left(z \cdot 2\right) \cdot z - y \cdot t}
\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 4 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: 82.0% accurate, 1.0× speedup?

\[\begin{array}{l} \\ x - \frac{\left(y \cdot 2\right) \cdot z}{\left(z \cdot 2\right) \cdot z - y \cdot t} \end{array} \]
(FPCore (x y z t)
 :precision binary64
 (- x (/ (* (* y 2.0) z) (- (* (* z 2.0) z) (* y t)))))
double code(double x, double y, double z, double t) {
	return x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t)));
}
real(8) function code(x, y, z, t)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    real(8), intent (in) :: t
    code = x - (((y * 2.0d0) * z) / (((z * 2.0d0) * z) - (y * t)))
end function
public static double code(double x, double y, double z, double t) {
	return x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t)));
}
def code(x, y, z, t):
	return x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t)))
function code(x, y, z, t)
	return Float64(x - Float64(Float64(Float64(y * 2.0) * z) / Float64(Float64(Float64(z * 2.0) * z) - Float64(y * t))))
end
function tmp = code(x, y, z, t)
	tmp = x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t)));
end
code[x_, y_, z_, t_] := N[(x - N[(N[(N[(y * 2.0), $MachinePrecision] * z), $MachinePrecision] / N[(N[(N[(z * 2.0), $MachinePrecision] * z), $MachinePrecision] - N[(y * t), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
x - \frac{\left(y \cdot 2\right) \cdot z}{\left(z \cdot 2\right) \cdot z - y \cdot t}
\end{array}

Alternative 1: 98.4% accurate, 1.1× speedup?

\[\begin{array}{l} \\ x + \frac{2 \cdot y}{y \cdot \frac{t}{z} - 2 \cdot z} \end{array} \]
(FPCore (x y z t)
 :precision binary64
 (+ x (/ (* 2.0 y) (- (* y (/ t z)) (* 2.0 z)))))
double code(double x, double y, double z, double t) {
	return x + ((2.0 * y) / ((y * (t / z)) - (2.0 * z)));
}
real(8) function code(x, y, z, t)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    real(8), intent (in) :: t
    code = x + ((2.0d0 * y) / ((y * (t / z)) - (2.0d0 * z)))
end function
public static double code(double x, double y, double z, double t) {
	return x + ((2.0 * y) / ((y * (t / z)) - (2.0 * z)));
}
def code(x, y, z, t):
	return x + ((2.0 * y) / ((y * (t / z)) - (2.0 * z)))
function code(x, y, z, t)
	return Float64(x + Float64(Float64(2.0 * y) / Float64(Float64(y * Float64(t / z)) - Float64(2.0 * z))))
end
function tmp = code(x, y, z, t)
	tmp = x + ((2.0 * y) / ((y * (t / z)) - (2.0 * z)));
end
code[x_, y_, z_, t_] := N[(x + N[(N[(2.0 * y), $MachinePrecision] / N[(N[(y * N[(t / z), $MachinePrecision]), $MachinePrecision] - N[(2.0 * z), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
x + \frac{2 \cdot y}{y \cdot \frac{t}{z} - 2 \cdot z}
\end{array}
Derivation
  1. Initial program 84.2%

    \[x - \frac{\left(y \cdot 2\right) \cdot z}{\left(z \cdot 2\right) \cdot z - y \cdot t} \]
  2. Simplified90.9%

    \[\leadsto \color{blue}{x - \left(y \cdot 2\right) \cdot \frac{z}{z \cdot \left(2 \cdot z\right) - y \cdot t}} \]
  3. Add Preprocessing
  4. Step-by-step derivation
    1. clear-num91.0%

      \[\leadsto x - \left(y \cdot 2\right) \cdot \color{blue}{\frac{1}{\frac{z \cdot \left(2 \cdot z\right) - y \cdot t}{z}}} \]
    2. un-div-inv91.0%

      \[\leadsto x - \color{blue}{\frac{y \cdot 2}{\frac{z \cdot \left(2 \cdot z\right) - y \cdot t}{z}}} \]
    3. *-commutative91.0%

      \[\leadsto x - \frac{\color{blue}{2 \cdot y}}{\frac{z \cdot \left(2 \cdot z\right) - y \cdot t}{z}} \]
    4. *-commutative91.0%

      \[\leadsto x - \frac{2 \cdot y}{\frac{\color{blue}{\left(2 \cdot z\right) \cdot z} - y \cdot t}{z}} \]
    5. associate-*l*91.0%

      \[\leadsto x - \frac{2 \cdot y}{\frac{\color{blue}{2 \cdot \left(z \cdot z\right)} - y \cdot t}{z}} \]
    6. pow291.0%

      \[\leadsto x - \frac{2 \cdot y}{\frac{2 \cdot \color{blue}{{z}^{2}} - y \cdot t}{z}} \]
  5. Applied egg-rr91.0%

    \[\leadsto x - \color{blue}{\frac{2 \cdot y}{\frac{2 \cdot {z}^{2} - y \cdot t}{z}}} \]
  6. Taylor expanded in z around 0 96.4%

    \[\leadsto x - \frac{2 \cdot y}{\color{blue}{-1 \cdot \frac{t \cdot y}{z} + 2 \cdot z}} \]
  7. Step-by-step derivation
    1. +-commutative96.4%

      \[\leadsto x - \frac{2 \cdot y}{\color{blue}{2 \cdot z + -1 \cdot \frac{t \cdot y}{z}}} \]
    2. mul-1-neg96.4%

      \[\leadsto x - \frac{2 \cdot y}{2 \cdot z + \color{blue}{\left(-\frac{t \cdot y}{z}\right)}} \]
    3. *-commutative96.4%

      \[\leadsto x - \frac{2 \cdot y}{2 \cdot z + \left(-\frac{\color{blue}{y \cdot t}}{z}\right)} \]
    4. associate-*r/98.1%

      \[\leadsto x - \frac{2 \cdot y}{2 \cdot z + \left(-\color{blue}{y \cdot \frac{t}{z}}\right)} \]
    5. unsub-neg98.1%

      \[\leadsto x - \frac{2 \cdot y}{\color{blue}{2 \cdot z - y \cdot \frac{t}{z}}} \]
    6. *-commutative98.1%

      \[\leadsto x - \frac{2 \cdot y}{\color{blue}{z \cdot 2} - y \cdot \frac{t}{z}} \]
  8. Simplified98.1%

    \[\leadsto x - \frac{2 \cdot y}{\color{blue}{z \cdot 2 - y \cdot \frac{t}{z}}} \]
  9. Final simplification98.1%

    \[\leadsto x + \frac{2 \cdot y}{y \cdot \frac{t}{z} - 2 \cdot z} \]
  10. Add Preprocessing

Alternative 2: 89.6% accurate, 0.6× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;z \leq -8.2 \cdot 10^{-11} \lor \neg \left(z \leq 1.15 \cdot 10^{-34}\right) \land \left(z \leq 1040000000000 \lor \neg \left(z \leq 7.8 \cdot 10^{+29}\right)\right):\\ \;\;\;\;x - \frac{y}{z}\\ \mathbf{else}:\\ \;\;\;\;x - \frac{z \cdot -2}{t}\\ \end{array} \end{array} \]
(FPCore (x y z t)
 :precision binary64
 (if (or (<= z -8.2e-11)
         (and (not (<= z 1.15e-34))
              (or (<= z 1040000000000.0) (not (<= z 7.8e+29)))))
   (- x (/ y z))
   (- x (/ (* z -2.0) t))))
double code(double x, double y, double z, double t) {
	double tmp;
	if ((z <= -8.2e-11) || (!(z <= 1.15e-34) && ((z <= 1040000000000.0) || !(z <= 7.8e+29)))) {
		tmp = x - (y / z);
	} else {
		tmp = x - ((z * -2.0) / t);
	}
	return tmp;
}
real(8) function code(x, y, z, t)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    real(8), intent (in) :: t
    real(8) :: tmp
    if ((z <= (-8.2d-11)) .or. (.not. (z <= 1.15d-34)) .and. (z <= 1040000000000.0d0) .or. (.not. (z <= 7.8d+29))) then
        tmp = x - (y / z)
    else
        tmp = x - ((z * (-2.0d0)) / t)
    end if
    code = tmp
end function
public static double code(double x, double y, double z, double t) {
	double tmp;
	if ((z <= -8.2e-11) || (!(z <= 1.15e-34) && ((z <= 1040000000000.0) || !(z <= 7.8e+29)))) {
		tmp = x - (y / z);
	} else {
		tmp = x - ((z * -2.0) / t);
	}
	return tmp;
}
def code(x, y, z, t):
	tmp = 0
	if (z <= -8.2e-11) or (not (z <= 1.15e-34) and ((z <= 1040000000000.0) or not (z <= 7.8e+29))):
		tmp = x - (y / z)
	else:
		tmp = x - ((z * -2.0) / t)
	return tmp
function code(x, y, z, t)
	tmp = 0.0
	if ((z <= -8.2e-11) || (!(z <= 1.15e-34) && ((z <= 1040000000000.0) || !(z <= 7.8e+29))))
		tmp = Float64(x - Float64(y / z));
	else
		tmp = Float64(x - Float64(Float64(z * -2.0) / t));
	end
	return tmp
end
function tmp_2 = code(x, y, z, t)
	tmp = 0.0;
	if ((z <= -8.2e-11) || (~((z <= 1.15e-34)) && ((z <= 1040000000000.0) || ~((z <= 7.8e+29)))))
		tmp = x - (y / z);
	else
		tmp = x - ((z * -2.0) / t);
	end
	tmp_2 = tmp;
end
code[x_, y_, z_, t_] := If[Or[LessEqual[z, -8.2e-11], And[N[Not[LessEqual[z, 1.15e-34]], $MachinePrecision], Or[LessEqual[z, 1040000000000.0], N[Not[LessEqual[z, 7.8e+29]], $MachinePrecision]]]], N[(x - N[(y / z), $MachinePrecision]), $MachinePrecision], N[(x - N[(N[(z * -2.0), $MachinePrecision] / t), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;z \leq -8.2 \cdot 10^{-11} \lor \neg \left(z \leq 1.15 \cdot 10^{-34}\right) \land \left(z \leq 1040000000000 \lor \neg \left(z \leq 7.8 \cdot 10^{+29}\right)\right):\\
\;\;\;\;x - \frac{y}{z}\\

\mathbf{else}:\\
\;\;\;\;x - \frac{z \cdot -2}{t}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if z < -8.2000000000000001e-11 or 1.15000000000000006e-34 < z < 1.04e12 or 7.79999999999999937e29 < z

    1. Initial program 76.6%

      \[x - \frac{\left(y \cdot 2\right) \cdot z}{\left(z \cdot 2\right) \cdot z - y \cdot t} \]
    2. Simplified90.3%

      \[\leadsto \color{blue}{x - \left(y \cdot 2\right) \cdot \frac{z}{z \cdot \left(2 \cdot z\right) - y \cdot t}} \]
    3. Add Preprocessing
    4. Taylor expanded in y around 0 90.3%

      \[\leadsto x - \color{blue}{\frac{y}{z}} \]

    if -8.2000000000000001e-11 < z < 1.15000000000000006e-34 or 1.04e12 < z < 7.79999999999999937e29

    1. Initial program 92.1%

      \[x - \frac{\left(y \cdot 2\right) \cdot z}{\left(z \cdot 2\right) \cdot z - y \cdot t} \]
    2. Simplified91.6%

      \[\leadsto \color{blue}{x - \left(y \cdot 2\right) \cdot \frac{z}{z \cdot \left(2 \cdot z\right) - y \cdot t}} \]
    3. Add Preprocessing
    4. Taylor expanded in y around inf 94.4%

      \[\leadsto x - \color{blue}{-2 \cdot \frac{z}{t}} \]
    5. Step-by-step derivation
      1. *-commutative94.4%

        \[\leadsto x - \color{blue}{\frac{z}{t} \cdot -2} \]
      2. associate-*l/94.4%

        \[\leadsto x - \color{blue}{\frac{z \cdot -2}{t}} \]
    6. Simplified94.4%

      \[\leadsto x - \color{blue}{\frac{z \cdot -2}{t}} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification92.3%

    \[\leadsto \begin{array}{l} \mathbf{if}\;z \leq -8.2 \cdot 10^{-11} \lor \neg \left(z \leq 1.15 \cdot 10^{-34}\right) \land \left(z \leq 1040000000000 \lor \neg \left(z \leq 7.8 \cdot 10^{+29}\right)\right):\\ \;\;\;\;x - \frac{y}{z}\\ \mathbf{else}:\\ \;\;\;\;x - \frac{z \cdot -2}{t}\\ \end{array} \]
  5. Add Preprocessing

Alternative 3: 82.7% accurate, 1.1× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;z \leq -205 \lor \neg \left(z \leq 3.2 \cdot 10^{-42}\right):\\ \;\;\;\;x - \frac{y}{z}\\ \mathbf{else}:\\ \;\;\;\;x\\ \end{array} \end{array} \]
(FPCore (x y z t)
 :precision binary64
 (if (or (<= z -205.0) (not (<= z 3.2e-42))) (- x (/ y z)) x))
double code(double x, double y, double z, double t) {
	double tmp;
	if ((z <= -205.0) || !(z <= 3.2e-42)) {
		tmp = x - (y / z);
	} else {
		tmp = x;
	}
	return tmp;
}
real(8) function code(x, y, z, t)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    real(8), intent (in) :: t
    real(8) :: tmp
    if ((z <= (-205.0d0)) .or. (.not. (z <= 3.2d-42))) then
        tmp = x - (y / z)
    else
        tmp = x
    end if
    code = tmp
end function
public static double code(double x, double y, double z, double t) {
	double tmp;
	if ((z <= -205.0) || !(z <= 3.2e-42)) {
		tmp = x - (y / z);
	} else {
		tmp = x;
	}
	return tmp;
}
def code(x, y, z, t):
	tmp = 0
	if (z <= -205.0) or not (z <= 3.2e-42):
		tmp = x - (y / z)
	else:
		tmp = x
	return tmp
function code(x, y, z, t)
	tmp = 0.0
	if ((z <= -205.0) || !(z <= 3.2e-42))
		tmp = Float64(x - Float64(y / z));
	else
		tmp = x;
	end
	return tmp
end
function tmp_2 = code(x, y, z, t)
	tmp = 0.0;
	if ((z <= -205.0) || ~((z <= 3.2e-42)))
		tmp = x - (y / z);
	else
		tmp = x;
	end
	tmp_2 = tmp;
end
code[x_, y_, z_, t_] := If[Or[LessEqual[z, -205.0], N[Not[LessEqual[z, 3.2e-42]], $MachinePrecision]], N[(x - N[(y / z), $MachinePrecision]), $MachinePrecision], x]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;z \leq -205 \lor \neg \left(z \leq 3.2 \cdot 10^{-42}\right):\\
\;\;\;\;x - \frac{y}{z}\\

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


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if z < -205 or 3.20000000000000025e-42 < z

    1. Initial program 77.9%

      \[x - \frac{\left(y \cdot 2\right) \cdot z}{\left(z \cdot 2\right) \cdot z - y \cdot t} \]
    2. Simplified90.9%

      \[\leadsto \color{blue}{x - \left(y \cdot 2\right) \cdot \frac{z}{z \cdot \left(2 \cdot z\right) - y \cdot t}} \]
    3. Add Preprocessing
    4. Taylor expanded in y around 0 86.0%

      \[\leadsto x - \color{blue}{\frac{y}{z}} \]

    if -205 < z < 3.20000000000000025e-42

    1. Initial program 91.6%

      \[x - \frac{\left(y \cdot 2\right) \cdot z}{\left(z \cdot 2\right) \cdot z - y \cdot t} \]
    2. Simplified91.0%

      \[\leadsto \color{blue}{x - \left(y \cdot 2\right) \cdot \frac{z}{z \cdot \left(2 \cdot z\right) - y \cdot t}} \]
    3. Add Preprocessing
    4. Taylor expanded in x around inf 72.1%

      \[\leadsto \color{blue}{x} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification79.6%

    \[\leadsto \begin{array}{l} \mathbf{if}\;z \leq -205 \lor \neg \left(z \leq 3.2 \cdot 10^{-42}\right):\\ \;\;\;\;x - \frac{y}{z}\\ \mathbf{else}:\\ \;\;\;\;x\\ \end{array} \]
  5. Add Preprocessing

Alternative 4: 75.5% accurate, 17.0× speedup?

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

\\
x
\end{array}
Derivation
  1. Initial program 84.2%

    \[x - \frac{\left(y \cdot 2\right) \cdot z}{\left(z \cdot 2\right) \cdot z - y \cdot t} \]
  2. Simplified90.9%

    \[\leadsto \color{blue}{x - \left(y \cdot 2\right) \cdot \frac{z}{z \cdot \left(2 \cdot z\right) - y \cdot t}} \]
  3. Add Preprocessing
  4. Taylor expanded in x around inf 72.6%

    \[\leadsto \color{blue}{x} \]
  5. Final simplification72.6%

    \[\leadsto x \]
  6. Add Preprocessing

Developer target: 99.9% accurate, 1.3× speedup?

\[\begin{array}{l} \\ x - \frac{1}{\frac{z}{y} - \frac{\frac{t}{2}}{z}} \end{array} \]
(FPCore (x y z t)
 :precision binary64
 (- x (/ 1.0 (- (/ z y) (/ (/ t 2.0) z)))))
double code(double x, double y, double z, double t) {
	return x - (1.0 / ((z / y) - ((t / 2.0) / z)));
}
real(8) function code(x, y, z, t)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    real(8), intent (in) :: t
    code = x - (1.0d0 / ((z / y) - ((t / 2.0d0) / z)))
end function
public static double code(double x, double y, double z, double t) {
	return x - (1.0 / ((z / y) - ((t / 2.0) / z)));
}
def code(x, y, z, t):
	return x - (1.0 / ((z / y) - ((t / 2.0) / z)))
function code(x, y, z, t)
	return Float64(x - Float64(1.0 / Float64(Float64(z / y) - Float64(Float64(t / 2.0) / z))))
end
function tmp = code(x, y, z, t)
	tmp = x - (1.0 / ((z / y) - ((t / 2.0) / z)));
end
code[x_, y_, z_, t_] := N[(x - N[(1.0 / N[(N[(z / y), $MachinePrecision] - N[(N[(t / 2.0), $MachinePrecision] / z), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
x - \frac{1}{\frac{z}{y} - \frac{\frac{t}{2}}{z}}
\end{array}

Reproduce

?
herbie shell --seed 2024047 
(FPCore (x y z t)
  :name "Numeric.AD.Rank1.Halley:findZero from ad-4.2.4"
  :precision binary64

  :alt
  (- x (/ 1.0 (- (/ z y) (/ (/ t 2.0) z))))

  (- x (/ (* (* y 2.0) z) (- (* (* z 2.0) z) (* y t)))))