fabs fraction 1

Percentage Accurate: 91.2% → 99.8%
Time: 9.0s
Alternatives: 8
Speedup: 1.6×

Specification

?
\[\begin{array}{l} \\ \left|\frac{x + 4}{y} - \frac{x}{y} \cdot z\right| \end{array} \]
(FPCore (x y z) :precision binary64 (fabs (- (/ (+ x 4.0) y) (* (/ x y) z))))
double code(double x, double y, double z) {
	return fabs((((x + 4.0) / y) - ((x / y) * z)));
}
real(8) function code(x, y, z)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    code = abs((((x + 4.0d0) / y) - ((x / y) * z)))
end function
public static double code(double x, double y, double z) {
	return Math.abs((((x + 4.0) / y) - ((x / y) * z)));
}
def code(x, y, z):
	return math.fabs((((x + 4.0) / y) - ((x / y) * z)))
function code(x, y, z)
	return abs(Float64(Float64(Float64(x + 4.0) / y) - Float64(Float64(x / y) * z)))
end
function tmp = code(x, y, z)
	tmp = abs((((x + 4.0) / y) - ((x / y) * z)));
end
code[x_, y_, z_] := N[Abs[N[(N[(N[(x + 4.0), $MachinePrecision] / y), $MachinePrecision] - N[(N[(x / y), $MachinePrecision] * z), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\left|\frac{x + 4}{y} - \frac{x}{y} \cdot z\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 8 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: 91.2% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \left|\frac{x + 4}{y} - \frac{x}{y} \cdot z\right| \end{array} \]
(FPCore (x y z) :precision binary64 (fabs (- (/ (+ x 4.0) y) (* (/ x y) z))))
double code(double x, double y, double z) {
	return fabs((((x + 4.0) / y) - ((x / y) * z)));
}
real(8) function code(x, y, z)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    code = abs((((x + 4.0d0) / y) - ((x / y) * z)))
end function
public static double code(double x, double y, double z) {
	return Math.abs((((x + 4.0) / y) - ((x / y) * z)));
}
def code(x, y, z):
	return math.fabs((((x + 4.0) / y) - ((x / y) * z)))
function code(x, y, z)
	return abs(Float64(Float64(Float64(x + 4.0) / y) - Float64(Float64(x / y) * z)))
end
function tmp = code(x, y, z)
	tmp = abs((((x + 4.0) / y) - ((x / y) * z)));
end
code[x_, y_, z_] := N[Abs[N[(N[(N[(x + 4.0), $MachinePrecision] / y), $MachinePrecision] - N[(N[(x / y), $MachinePrecision] * z), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\left|\frac{x + 4}{y} - \frac{x}{y} \cdot z\right|
\end{array}

Alternative 1: 99.8% accurate, 0.9× speedup?

\[\begin{array}{l} y_m = \left|y\right| \\ \begin{array}{l} \mathbf{if}\;y\_m \leq 2 \cdot 10^{-29}:\\ \;\;\;\;\left|\frac{\mathsf{fma}\left(x, z, -4 - x\right)}{y\_m}\right|\\ \mathbf{else}:\\ \;\;\;\;\left|\mathsf{fma}\left(-x, \frac{z}{y\_m}, \frac{x + 4}{y\_m}\right)\right|\\ \end{array} \end{array} \]
y_m = (fabs.f64 y)
(FPCore (x y_m z)
 :precision binary64
 (if (<= y_m 2e-29)
   (fabs (/ (fma x z (- -4.0 x)) y_m))
   (fabs (fma (- x) (/ z y_m) (/ (+ x 4.0) y_m)))))
y_m = fabs(y);
double code(double x, double y_m, double z) {
	double tmp;
	if (y_m <= 2e-29) {
		tmp = fabs((fma(x, z, (-4.0 - x)) / y_m));
	} else {
		tmp = fabs(fma(-x, (z / y_m), ((x + 4.0) / y_m)));
	}
	return tmp;
}
y_m = abs(y)
function code(x, y_m, z)
	tmp = 0.0
	if (y_m <= 2e-29)
		tmp = abs(Float64(fma(x, z, Float64(-4.0 - x)) / y_m));
	else
		tmp = abs(fma(Float64(-x), Float64(z / y_m), Float64(Float64(x + 4.0) / y_m)));
	end
	return tmp
end
y_m = N[Abs[y], $MachinePrecision]
code[x_, y$95$m_, z_] := If[LessEqual[y$95$m, 2e-29], N[Abs[N[(N[(x * z + N[(-4.0 - x), $MachinePrecision]), $MachinePrecision] / y$95$m), $MachinePrecision]], $MachinePrecision], N[Abs[N[((-x) * N[(z / y$95$m), $MachinePrecision] + N[(N[(x + 4.0), $MachinePrecision] / y$95$m), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]]
\begin{array}{l}
y_m = \left|y\right|

\\
\begin{array}{l}
\mathbf{if}\;y\_m \leq 2 \cdot 10^{-29}:\\
\;\;\;\;\left|\frac{\mathsf{fma}\left(x, z, -4 - x\right)}{y\_m}\right|\\

\mathbf{else}:\\
\;\;\;\;\left|\mathsf{fma}\left(-x, \frac{z}{y\_m}, \frac{x + 4}{y\_m}\right)\right|\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if y < 1.99999999999999989e-29

    1. Initial program 80.6%

      \[\left|\frac{x + 4}{y} - \frac{x}{y} \cdot z\right| \]
    2. Add Preprocessing
    3. Step-by-step derivation
      1. lift-fabs.f64N/A

        \[\leadsto \color{blue}{\left|\frac{x + 4}{y} - \frac{x}{y} \cdot z\right|} \]
      2. neg-fabsN/A

        \[\leadsto \color{blue}{\left|\mathsf{neg}\left(\left(\frac{x + 4}{y} - \frac{x}{y} \cdot z\right)\right)\right|} \]
      3. lower-fabs.f64N/A

        \[\leadsto \color{blue}{\left|\mathsf{neg}\left(\left(\frac{x + 4}{y} - \frac{x}{y} \cdot z\right)\right)\right|} \]
      4. lift--.f64N/A

        \[\leadsto \left|\mathsf{neg}\left(\color{blue}{\left(\frac{x + 4}{y} - \frac{x}{y} \cdot z\right)}\right)\right| \]
      5. sub-negN/A

        \[\leadsto \left|\mathsf{neg}\left(\color{blue}{\left(\frac{x + 4}{y} + \left(\mathsf{neg}\left(\frac{x}{y} \cdot z\right)\right)\right)}\right)\right| \]
      6. +-commutativeN/A

        \[\leadsto \left|\mathsf{neg}\left(\color{blue}{\left(\left(\mathsf{neg}\left(\frac{x}{y} \cdot z\right)\right) + \frac{x + 4}{y}\right)}\right)\right| \]
      7. distribute-neg-inN/A

        \[\leadsto \left|\color{blue}{\left(\mathsf{neg}\left(\left(\mathsf{neg}\left(\frac{x}{y} \cdot z\right)\right)\right)\right) + \left(\mathsf{neg}\left(\frac{x + 4}{y}\right)\right)}\right| \]
      8. remove-double-negN/A

        \[\leadsto \left|\color{blue}{\frac{x}{y} \cdot z} + \left(\mathsf{neg}\left(\frac{x + 4}{y}\right)\right)\right| \]
      9. sub-negN/A

        \[\leadsto \left|\color{blue}{\frac{x}{y} \cdot z - \frac{x + 4}{y}}\right| \]
      10. lift-*.f64N/A

        \[\leadsto \left|\color{blue}{\frac{x}{y} \cdot z} - \frac{x + 4}{y}\right| \]
      11. lift-/.f64N/A

        \[\leadsto \left|\color{blue}{\frac{x}{y}} \cdot z - \frac{x + 4}{y}\right| \]
      12. associate-*l/N/A

        \[\leadsto \left|\color{blue}{\frac{x \cdot z}{y}} - \frac{x + 4}{y}\right| \]
      13. lift-/.f64N/A

        \[\leadsto \left|\frac{x \cdot z}{y} - \color{blue}{\frac{x + 4}{y}}\right| \]
      14. sub-divN/A

        \[\leadsto \left|\color{blue}{\frac{x \cdot z - \left(x + 4\right)}{y}}\right| \]
      15. lower-/.f64N/A

        \[\leadsto \left|\color{blue}{\frac{x \cdot z - \left(x + 4\right)}{y}}\right| \]
      16. sub-negN/A

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

        \[\leadsto \left|\frac{\color{blue}{\mathsf{fma}\left(x, z, \mathsf{neg}\left(\left(x + 4\right)\right)\right)}}{y}\right| \]
      18. lift-+.f64N/A

        \[\leadsto \left|\frac{\mathsf{fma}\left(x, z, \mathsf{neg}\left(\color{blue}{\left(x + 4\right)}\right)\right)}{y}\right| \]
      19. +-commutativeN/A

        \[\leadsto \left|\frac{\mathsf{fma}\left(x, z, \mathsf{neg}\left(\color{blue}{\left(4 + x\right)}\right)\right)}{y}\right| \]
      20. distribute-neg-inN/A

        \[\leadsto \left|\frac{\mathsf{fma}\left(x, z, \color{blue}{\left(\mathsf{neg}\left(4\right)\right) + \left(\mathsf{neg}\left(x\right)\right)}\right)}{y}\right| \]
      21. unsub-negN/A

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

        \[\leadsto \left|\frac{\mathsf{fma}\left(x, z, \color{blue}{\left(\mathsf{neg}\left(4\right)\right) - x}\right)}{y}\right| \]
      23. metadata-eval99.9

        \[\leadsto \left|\frac{\mathsf{fma}\left(x, z, \color{blue}{-4} - x\right)}{y}\right| \]
    4. Applied rewrites99.9%

      \[\leadsto \color{blue}{\left|\frac{\mathsf{fma}\left(x, z, -4 - x\right)}{y}\right|} \]

    if 1.99999999999999989e-29 < y

    1. Initial program 96.0%

      \[\left|\frac{x + 4}{y} - \frac{x}{y} \cdot z\right| \]
    2. Add Preprocessing
    3. Step-by-step derivation
      1. lift--.f64N/A

        \[\leadsto \left|\color{blue}{\frac{x + 4}{y} - \frac{x}{y} \cdot z}\right| \]
      2. sub-negN/A

        \[\leadsto \left|\color{blue}{\frac{x + 4}{y} + \left(\mathsf{neg}\left(\frac{x}{y} \cdot z\right)\right)}\right| \]
      3. +-commutativeN/A

        \[\leadsto \left|\color{blue}{\left(\mathsf{neg}\left(\frac{x}{y} \cdot z\right)\right) + \frac{x + 4}{y}}\right| \]
      4. lift-*.f64N/A

        \[\leadsto \left|\left(\mathsf{neg}\left(\color{blue}{\frac{x}{y} \cdot z}\right)\right) + \frac{x + 4}{y}\right| \]
      5. lift-/.f64N/A

        \[\leadsto \left|\left(\mathsf{neg}\left(\color{blue}{\frac{x}{y}} \cdot z\right)\right) + \frac{x + 4}{y}\right| \]
      6. associate-*l/N/A

        \[\leadsto \left|\left(\mathsf{neg}\left(\color{blue}{\frac{x \cdot z}{y}}\right)\right) + \frac{x + 4}{y}\right| \]
      7. associate-/l*N/A

        \[\leadsto \left|\left(\mathsf{neg}\left(\color{blue}{x \cdot \frac{z}{y}}\right)\right) + \frac{x + 4}{y}\right| \]
      8. distribute-lft-neg-inN/A

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

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

        \[\leadsto \left|\mathsf{fma}\left(\color{blue}{\mathsf{neg}\left(x\right)}, \frac{z}{y}, \frac{x + 4}{y}\right)\right| \]
      11. lower-/.f6499.9

        \[\leadsto \left|\mathsf{fma}\left(-x, \color{blue}{\frac{z}{y}}, \frac{x + 4}{y}\right)\right| \]
    4. Applied rewrites99.9%

      \[\leadsto \left|\color{blue}{\mathsf{fma}\left(-x, \frac{z}{y}, \frac{x + 4}{y}\right)}\right| \]
  3. Recombined 2 regimes into one program.
  4. Add Preprocessing

Alternative 2: 99.2% accurate, 0.3× speedup?

\[\begin{array}{l} y_m = \left|y\right| \\ \begin{array}{l} t_0 := \left|\frac{x + 4}{y\_m} - z \cdot \frac{x}{y\_m}\right|\\ \mathbf{if}\;t\_0 \leq 5 \cdot 10^{-203}:\\ \;\;\;\;\left|\frac{1}{y\_m} \cdot \left(x + \left(4 - x \cdot z\right)\right)\right|\\ \mathbf{elif}\;t\_0 \leq \infty:\\ \;\;\;\;t\_0\\ \mathbf{else}:\\ \;\;\;\;\left|\frac{-x}{y\_m}\right|\\ \end{array} \end{array} \]
y_m = (fabs.f64 y)
(FPCore (x y_m z)
 :precision binary64
 (let* ((t_0 (fabs (- (/ (+ x 4.0) y_m) (* z (/ x y_m))))))
   (if (<= t_0 5e-203)
     (fabs (* (/ 1.0 y_m) (+ x (- 4.0 (* x z)))))
     (if (<= t_0 INFINITY) t_0 (fabs (/ (- x) y_m))))))
y_m = fabs(y);
double code(double x, double y_m, double z) {
	double t_0 = fabs((((x + 4.0) / y_m) - (z * (x / y_m))));
	double tmp;
	if (t_0 <= 5e-203) {
		tmp = fabs(((1.0 / y_m) * (x + (4.0 - (x * z)))));
	} else if (t_0 <= ((double) INFINITY)) {
		tmp = t_0;
	} else {
		tmp = fabs((-x / y_m));
	}
	return tmp;
}
y_m = Math.abs(y);
public static double code(double x, double y_m, double z) {
	double t_0 = Math.abs((((x + 4.0) / y_m) - (z * (x / y_m))));
	double tmp;
	if (t_0 <= 5e-203) {
		tmp = Math.abs(((1.0 / y_m) * (x + (4.0 - (x * z)))));
	} else if (t_0 <= Double.POSITIVE_INFINITY) {
		tmp = t_0;
	} else {
		tmp = Math.abs((-x / y_m));
	}
	return tmp;
}
y_m = math.fabs(y)
def code(x, y_m, z):
	t_0 = math.fabs((((x + 4.0) / y_m) - (z * (x / y_m))))
	tmp = 0
	if t_0 <= 5e-203:
		tmp = math.fabs(((1.0 / y_m) * (x + (4.0 - (x * z)))))
	elif t_0 <= math.inf:
		tmp = t_0
	else:
		tmp = math.fabs((-x / y_m))
	return tmp
y_m = abs(y)
function code(x, y_m, z)
	t_0 = abs(Float64(Float64(Float64(x + 4.0) / y_m) - Float64(z * Float64(x / y_m))))
	tmp = 0.0
	if (t_0 <= 5e-203)
		tmp = abs(Float64(Float64(1.0 / y_m) * Float64(x + Float64(4.0 - Float64(x * z)))));
	elseif (t_0 <= Inf)
		tmp = t_0;
	else
		tmp = abs(Float64(Float64(-x) / y_m));
	end
	return tmp
end
y_m = abs(y);
function tmp_2 = code(x, y_m, z)
	t_0 = abs((((x + 4.0) / y_m) - (z * (x / y_m))));
	tmp = 0.0;
	if (t_0 <= 5e-203)
		tmp = abs(((1.0 / y_m) * (x + (4.0 - (x * z)))));
	elseif (t_0 <= Inf)
		tmp = t_0;
	else
		tmp = abs((-x / y_m));
	end
	tmp_2 = tmp;
end
y_m = N[Abs[y], $MachinePrecision]
code[x_, y$95$m_, z_] := Block[{t$95$0 = N[Abs[N[(N[(N[(x + 4.0), $MachinePrecision] / y$95$m), $MachinePrecision] - N[(z * N[(x / y$95$m), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]}, If[LessEqual[t$95$0, 5e-203], N[Abs[N[(N[(1.0 / y$95$m), $MachinePrecision] * N[(x + N[(4.0 - N[(x * z), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision], If[LessEqual[t$95$0, Infinity], t$95$0, N[Abs[N[((-x) / y$95$m), $MachinePrecision]], $MachinePrecision]]]]
\begin{array}{l}
y_m = \left|y\right|

\\
\begin{array}{l}
t_0 := \left|\frac{x + 4}{y\_m} - z \cdot \frac{x}{y\_m}\right|\\
\mathbf{if}\;t\_0 \leq 5 \cdot 10^{-203}:\\
\;\;\;\;\left|\frac{1}{y\_m} \cdot \left(x + \left(4 - x \cdot z\right)\right)\right|\\

\mathbf{elif}\;t\_0 \leq \infty:\\
\;\;\;\;t\_0\\

\mathbf{else}:\\
\;\;\;\;\left|\frac{-x}{y\_m}\right|\\


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if (fabs.f64 (-.f64 (/.f64 (+.f64 x #s(literal 4 binary64)) y) (*.f64 (/.f64 x y) z))) < 5.0000000000000002e-203

    1. Initial program 83.3%

      \[\left|\frac{x + 4}{y} - \frac{x}{y} \cdot z\right| \]
    2. Add Preprocessing
    3. Step-by-step derivation
      1. lift--.f64N/A

        \[\leadsto \left|\color{blue}{\frac{x + 4}{y} - \frac{x}{y} \cdot z}\right| \]
      2. lift-/.f64N/A

        \[\leadsto \left|\color{blue}{\frac{x + 4}{y}} - \frac{x}{y} \cdot z\right| \]
      3. div-invN/A

        \[\leadsto \left|\color{blue}{\left(x + 4\right) \cdot \frac{1}{y}} - \frac{x}{y} \cdot z\right| \]
      4. lift-*.f64N/A

        \[\leadsto \left|\left(x + 4\right) \cdot \frac{1}{y} - \color{blue}{\frac{x}{y} \cdot z}\right| \]
      5. lift-/.f64N/A

        \[\leadsto \left|\left(x + 4\right) \cdot \frac{1}{y} - \color{blue}{\frac{x}{y}} \cdot z\right| \]
      6. associate-*l/N/A

        \[\leadsto \left|\left(x + 4\right) \cdot \frac{1}{y} - \color{blue}{\frac{x \cdot z}{y}}\right| \]
      7. div-invN/A

        \[\leadsto \left|\left(x + 4\right) \cdot \frac{1}{y} - \color{blue}{\left(x \cdot z\right) \cdot \frac{1}{y}}\right| \]
      8. distribute-rgt-out--N/A

        \[\leadsto \left|\color{blue}{\frac{1}{y} \cdot \left(\left(x + 4\right) - x \cdot z\right)}\right| \]
      9. lower-*.f64N/A

        \[\leadsto \left|\color{blue}{\frac{1}{y} \cdot \left(\left(x + 4\right) - x \cdot z\right)}\right| \]
      10. lower-/.f64N/A

        \[\leadsto \left|\color{blue}{\frac{1}{y}} \cdot \left(\left(x + 4\right) - x \cdot z\right)\right| \]
      11. lift-+.f64N/A

        \[\leadsto \left|\frac{1}{y} \cdot \left(\color{blue}{\left(x + 4\right)} - x \cdot z\right)\right| \]
      12. associate--l+N/A

        \[\leadsto \left|\frac{1}{y} \cdot \color{blue}{\left(x + \left(4 - x \cdot z\right)\right)}\right| \]
      13. lower-+.f64N/A

        \[\leadsto \left|\frac{1}{y} \cdot \color{blue}{\left(x + \left(4 - x \cdot z\right)\right)}\right| \]
      14. lower--.f64N/A

        \[\leadsto \left|\frac{1}{y} \cdot \left(x + \color{blue}{\left(4 - x \cdot z\right)}\right)\right| \]
      15. lower-*.f6499.8

        \[\leadsto \left|\frac{1}{y} \cdot \left(x + \left(4 - \color{blue}{x \cdot z}\right)\right)\right| \]
    4. Applied rewrites99.8%

      \[\leadsto \left|\color{blue}{\frac{1}{y} \cdot \left(x + \left(4 - x \cdot z\right)\right)}\right| \]

    if 5.0000000000000002e-203 < (fabs.f64 (-.f64 (/.f64 (+.f64 x #s(literal 4 binary64)) y) (*.f64 (/.f64 x y) z))) < +inf.0

    1. Initial program 99.0%

      \[\left|\frac{x + 4}{y} - \frac{x}{y} \cdot z\right| \]
    2. Add Preprocessing

    if +inf.0 < (fabs.f64 (-.f64 (/.f64 (+.f64 x #s(literal 4 binary64)) y) (*.f64 (/.f64 x y) z)))

    1. Initial program 0.0%

      \[\left|\frac{x + 4}{y} - \frac{x}{y} \cdot z\right| \]
    2. Add Preprocessing
    3. Step-by-step derivation
      1. lift-fabs.f64N/A

        \[\leadsto \color{blue}{\left|\frac{x + 4}{y} - \frac{x}{y} \cdot z\right|} \]
      2. neg-fabsN/A

        \[\leadsto \color{blue}{\left|\mathsf{neg}\left(\left(\frac{x + 4}{y} - \frac{x}{y} \cdot z\right)\right)\right|} \]
      3. lower-fabs.f64N/A

        \[\leadsto \color{blue}{\left|\mathsf{neg}\left(\left(\frac{x + 4}{y} - \frac{x}{y} \cdot z\right)\right)\right|} \]
      4. lift--.f64N/A

        \[\leadsto \left|\mathsf{neg}\left(\color{blue}{\left(\frac{x + 4}{y} - \frac{x}{y} \cdot z\right)}\right)\right| \]
      5. sub-negN/A

        \[\leadsto \left|\mathsf{neg}\left(\color{blue}{\left(\frac{x + 4}{y} + \left(\mathsf{neg}\left(\frac{x}{y} \cdot z\right)\right)\right)}\right)\right| \]
      6. +-commutativeN/A

        \[\leadsto \left|\mathsf{neg}\left(\color{blue}{\left(\left(\mathsf{neg}\left(\frac{x}{y} \cdot z\right)\right) + \frac{x + 4}{y}\right)}\right)\right| \]
      7. distribute-neg-inN/A

        \[\leadsto \left|\color{blue}{\left(\mathsf{neg}\left(\left(\mathsf{neg}\left(\frac{x}{y} \cdot z\right)\right)\right)\right) + \left(\mathsf{neg}\left(\frac{x + 4}{y}\right)\right)}\right| \]
      8. remove-double-negN/A

        \[\leadsto \left|\color{blue}{\frac{x}{y} \cdot z} + \left(\mathsf{neg}\left(\frac{x + 4}{y}\right)\right)\right| \]
      9. sub-negN/A

        \[\leadsto \left|\color{blue}{\frac{x}{y} \cdot z - \frac{x + 4}{y}}\right| \]
      10. lift-*.f64N/A

        \[\leadsto \left|\color{blue}{\frac{x}{y} \cdot z} - \frac{x + 4}{y}\right| \]
      11. lift-/.f64N/A

        \[\leadsto \left|\color{blue}{\frac{x}{y}} \cdot z - \frac{x + 4}{y}\right| \]
      12. associate-*l/N/A

        \[\leadsto \left|\color{blue}{\frac{x \cdot z}{y}} - \frac{x + 4}{y}\right| \]
      13. lift-/.f64N/A

        \[\leadsto \left|\frac{x \cdot z}{y} - \color{blue}{\frac{x + 4}{y}}\right| \]
      14. sub-divN/A

        \[\leadsto \left|\color{blue}{\frac{x \cdot z - \left(x + 4\right)}{y}}\right| \]
      15. lower-/.f64N/A

        \[\leadsto \left|\color{blue}{\frac{x \cdot z - \left(x + 4\right)}{y}}\right| \]
      16. sub-negN/A

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

        \[\leadsto \left|\frac{\color{blue}{\mathsf{fma}\left(x, z, \mathsf{neg}\left(\left(x + 4\right)\right)\right)}}{y}\right| \]
      18. lift-+.f64N/A

        \[\leadsto \left|\frac{\mathsf{fma}\left(x, z, \mathsf{neg}\left(\color{blue}{\left(x + 4\right)}\right)\right)}{y}\right| \]
      19. +-commutativeN/A

        \[\leadsto \left|\frac{\mathsf{fma}\left(x, z, \mathsf{neg}\left(\color{blue}{\left(4 + x\right)}\right)\right)}{y}\right| \]
      20. distribute-neg-inN/A

        \[\leadsto \left|\frac{\mathsf{fma}\left(x, z, \color{blue}{\left(\mathsf{neg}\left(4\right)\right) + \left(\mathsf{neg}\left(x\right)\right)}\right)}{y}\right| \]
      21. unsub-negN/A

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

        \[\leadsto \left|\frac{\mathsf{fma}\left(x, z, \color{blue}{\left(\mathsf{neg}\left(4\right)\right) - x}\right)}{y}\right| \]
      23. metadata-eval100.0

        \[\leadsto \left|\frac{\mathsf{fma}\left(x, z, \color{blue}{-4} - x\right)}{y}\right| \]
    4. Applied rewrites100.0%

      \[\leadsto \color{blue}{\left|\frac{\mathsf{fma}\left(x, z, -4 - x\right)}{y}\right|} \]
    5. Taylor expanded in z around 0

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

        \[\leadsto \left|\frac{\color{blue}{-1 \cdot 4 + -1 \cdot x}}{y}\right| \]
      2. metadata-evalN/A

        \[\leadsto \left|\frac{\color{blue}{-4} + -1 \cdot x}{y}\right| \]
      3. mul-1-negN/A

        \[\leadsto \left|\frac{-4 + \color{blue}{\left(\mathsf{neg}\left(x\right)\right)}}{y}\right| \]
      4. unsub-negN/A

        \[\leadsto \left|\frac{\color{blue}{-4 - x}}{y}\right| \]
      5. lower--.f64100.0

        \[\leadsto \left|\frac{\color{blue}{-4 - x}}{y}\right| \]
    7. Applied rewrites100.0%

      \[\leadsto \left|\frac{\color{blue}{-4 - x}}{y}\right| \]
    8. Taylor expanded in x around inf

      \[\leadsto \left|\frac{-1 \cdot \color{blue}{x}}{y}\right| \]
    9. Step-by-step derivation
      1. Applied rewrites100.0%

        \[\leadsto \left|\frac{-x}{y}\right| \]
    10. Recombined 3 regimes into one program.
    11. Final simplification99.2%

      \[\leadsto \begin{array}{l} \mathbf{if}\;\left|\frac{x + 4}{y} - z \cdot \frac{x}{y}\right| \leq 5 \cdot 10^{-203}:\\ \;\;\;\;\left|\frac{1}{y} \cdot \left(x + \left(4 - x \cdot z\right)\right)\right|\\ \mathbf{elif}\;\left|\frac{x + 4}{y} - z \cdot \frac{x}{y}\right| \leq \infty:\\ \;\;\;\;\left|\frac{x + 4}{y} - z \cdot \frac{x}{y}\right|\\ \mathbf{else}:\\ \;\;\;\;\left|\frac{-x}{y}\right|\\ \end{array} \]
    12. Add Preprocessing

    Reproduce

    ?
    herbie shell --seed 2024219 
    (FPCore (x y z)
      :name "fabs fraction 1"
      :precision binary64
      (fabs (- (/ (+ x 4.0) y) (* (/ x y) z))))