Quotient of products

Percentage Accurate: 86.4% → 94.8%
Time: 2.4s
Alternatives: 5
Speedup: 0.2×

Specification

?
\[\begin{array}{l} \\ \frac{a1 \cdot a2}{b1 \cdot b2} \end{array} \]
(FPCore (a1 a2 b1 b2) :precision binary64 (/ (* a1 a2) (* b1 b2)))
double code(double a1, double a2, double b1, double b2) {
	return (a1 * a2) / (b1 * b2);
}
real(8) function code(a1, a2, b1, b2)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2
    real(8), intent (in) :: b1
    real(8), intent (in) :: b2
    code = (a1 * a2) / (b1 * b2)
end function
public static double code(double a1, double a2, double b1, double b2) {
	return (a1 * a2) / (b1 * b2);
}
def code(a1, a2, b1, b2):
	return (a1 * a2) / (b1 * b2)
function code(a1, a2, b1, b2)
	return Float64(Float64(a1 * a2) / Float64(b1 * b2))
end
function tmp = code(a1, a2, b1, b2)
	tmp = (a1 * a2) / (b1 * b2);
end
code[a1_, a2_, b1_, b2_] := N[(N[(a1 * a2), $MachinePrecision] / N[(b1 * b2), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{a1 \cdot a2}{b1 \cdot b2}
\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: 86.4% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{a1 \cdot a2}{b1 \cdot b2} \end{array} \]
(FPCore (a1 a2 b1 b2) :precision binary64 (/ (* a1 a2) (* b1 b2)))
double code(double a1, double a2, double b1, double b2) {
	return (a1 * a2) / (b1 * b2);
}
real(8) function code(a1, a2, b1, b2)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2
    real(8), intent (in) :: b1
    real(8), intent (in) :: b2
    code = (a1 * a2) / (b1 * b2)
end function
public static double code(double a1, double a2, double b1, double b2) {
	return (a1 * a2) / (b1 * b2);
}
def code(a1, a2, b1, b2):
	return (a1 * a2) / (b1 * b2)
function code(a1, a2, b1, b2)
	return Float64(Float64(a1 * a2) / Float64(b1 * b2))
end
function tmp = code(a1, a2, b1, b2)
	tmp = (a1 * a2) / (b1 * b2);
end
code[a1_, a2_, b1_, b2_] := N[(N[(a1 * a2), $MachinePrecision] / N[(b1 * b2), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{a1 \cdot a2}{b1 \cdot b2}
\end{array}

Alternative 1: 94.8% accurate, 0.2× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \frac{a1 \cdot a2}{b1 \cdot b2}\\ \mathbf{if}\;t_0 \leq -2 \cdot 10^{-295} \lor \neg \left(t_0 \leq 0\right) \land t_0 \leq 10^{+260}:\\ \;\;\;\;t_0\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{a1}{b2}}{\frac{b1}{a2}}\\ \end{array} \end{array} \]
(FPCore (a1 a2 b1 b2)
 :precision binary64
 (let* ((t_0 (/ (* a1 a2) (* b1 b2))))
   (if (or (<= t_0 -2e-295) (and (not (<= t_0 0.0)) (<= t_0 1e+260)))
     t_0
     (/ (/ a1 b2) (/ b1 a2)))))
double code(double a1, double a2, double b1, double b2) {
	double t_0 = (a1 * a2) / (b1 * b2);
	double tmp;
	if ((t_0 <= -2e-295) || (!(t_0 <= 0.0) && (t_0 <= 1e+260))) {
		tmp = t_0;
	} else {
		tmp = (a1 / b2) / (b1 / a2);
	}
	return tmp;
}
real(8) function code(a1, a2, b1, b2)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2
    real(8), intent (in) :: b1
    real(8), intent (in) :: b2
    real(8) :: t_0
    real(8) :: tmp
    t_0 = (a1 * a2) / (b1 * b2)
    if ((t_0 <= (-2d-295)) .or. (.not. (t_0 <= 0.0d0)) .and. (t_0 <= 1d+260)) then
        tmp = t_0
    else
        tmp = (a1 / b2) / (b1 / a2)
    end if
    code = tmp
end function
public static double code(double a1, double a2, double b1, double b2) {
	double t_0 = (a1 * a2) / (b1 * b2);
	double tmp;
	if ((t_0 <= -2e-295) || (!(t_0 <= 0.0) && (t_0 <= 1e+260))) {
		tmp = t_0;
	} else {
		tmp = (a1 / b2) / (b1 / a2);
	}
	return tmp;
}
def code(a1, a2, b1, b2):
	t_0 = (a1 * a2) / (b1 * b2)
	tmp = 0
	if (t_0 <= -2e-295) or (not (t_0 <= 0.0) and (t_0 <= 1e+260)):
		tmp = t_0
	else:
		tmp = (a1 / b2) / (b1 / a2)
	return tmp
function code(a1, a2, b1, b2)
	t_0 = Float64(Float64(a1 * a2) / Float64(b1 * b2))
	tmp = 0.0
	if ((t_0 <= -2e-295) || (!(t_0 <= 0.0) && (t_0 <= 1e+260)))
		tmp = t_0;
	else
		tmp = Float64(Float64(a1 / b2) / Float64(b1 / a2));
	end
	return tmp
end
function tmp_2 = code(a1, a2, b1, b2)
	t_0 = (a1 * a2) / (b1 * b2);
	tmp = 0.0;
	if ((t_0 <= -2e-295) || (~((t_0 <= 0.0)) && (t_0 <= 1e+260)))
		tmp = t_0;
	else
		tmp = (a1 / b2) / (b1 / a2);
	end
	tmp_2 = tmp;
end
code[a1_, a2_, b1_, b2_] := Block[{t$95$0 = N[(N[(a1 * a2), $MachinePrecision] / N[(b1 * b2), $MachinePrecision]), $MachinePrecision]}, If[Or[LessEqual[t$95$0, -2e-295], And[N[Not[LessEqual[t$95$0, 0.0]], $MachinePrecision], LessEqual[t$95$0, 1e+260]]], t$95$0, N[(N[(a1 / b2), $MachinePrecision] / N[(b1 / a2), $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \frac{a1 \cdot a2}{b1 \cdot b2}\\
\mathbf{if}\;t_0 \leq -2 \cdot 10^{-295} \lor \neg \left(t_0 \leq 0\right) \land t_0 \leq 10^{+260}:\\
\;\;\;\;t_0\\

\mathbf{else}:\\
\;\;\;\;\frac{\frac{a1}{b2}}{\frac{b1}{a2}}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (/.f64 (*.f64 a1 a2) (*.f64 b1 b2)) < -2.00000000000000012e-295 or 0.0 < (/.f64 (*.f64 a1 a2) (*.f64 b1 b2)) < 1.00000000000000007e260

    1. Initial program 95.7%

      \[\frac{a1 \cdot a2}{b1 \cdot b2} \]

    if -2.00000000000000012e-295 < (/.f64 (*.f64 a1 a2) (*.f64 b1 b2)) < 0.0 or 1.00000000000000007e260 < (/.f64 (*.f64 a1 a2) (*.f64 b1 b2))

    1. Initial program 69.9%

      \[\frac{a1 \cdot a2}{b1 \cdot b2} \]
    2. Step-by-step derivation
      1. times-frac96.1%

        \[\leadsto \color{blue}{\frac{a1}{b1} \cdot \frac{a2}{b2}} \]
    3. Simplified96.1%

      \[\leadsto \color{blue}{\frac{a1}{b1} \cdot \frac{a2}{b2}} \]
    4. Step-by-step derivation
      1. frac-times69.9%

        \[\leadsto \color{blue}{\frac{a1 \cdot a2}{b1 \cdot b2}} \]
      2. *-commutative69.9%

        \[\leadsto \frac{a1 \cdot a2}{\color{blue}{b2 \cdot b1}} \]
      3. frac-times99.8%

        \[\leadsto \color{blue}{\frac{a1}{b2} \cdot \frac{a2}{b1}} \]
      4. clear-num99.8%

        \[\leadsto \frac{a1}{b2} \cdot \color{blue}{\frac{1}{\frac{b1}{a2}}} \]
      5. un-div-inv99.8%

        \[\leadsto \color{blue}{\frac{\frac{a1}{b2}}{\frac{b1}{a2}}} \]
    5. Applied egg-rr99.8%

      \[\leadsto \color{blue}{\frac{\frac{a1}{b2}}{\frac{b1}{a2}}} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification97.7%

    \[\leadsto \begin{array}{l} \mathbf{if}\;\frac{a1 \cdot a2}{b1 \cdot b2} \leq -2 \cdot 10^{-295} \lor \neg \left(\frac{a1 \cdot a2}{b1 \cdot b2} \leq 0\right) \land \frac{a1 \cdot a2}{b1 \cdot b2} \leq 10^{+260}:\\ \;\;\;\;\frac{a1 \cdot a2}{b1 \cdot b2}\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{a1}{b2}}{\frac{b1}{a2}}\\ \end{array} \]

Alternative 2: 95.4% accurate, 0.2× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := \frac{a1 \cdot a2}{b1 \cdot b2}\\ \mathbf{if}\;t_0 \leq -1 \cdot 10^{-315} \lor \neg \left(t_0 \leq 0\right) \land t_0 \leq 5 \cdot 10^{+306}:\\ \;\;\;\;t_0\\ \mathbf{else}:\\ \;\;\;\;\frac{a1}{b1} \cdot \frac{a2}{b2}\\ \end{array} \end{array} \]
(FPCore (a1 a2 b1 b2)
 :precision binary64
 (let* ((t_0 (/ (* a1 a2) (* b1 b2))))
   (if (or (<= t_0 -1e-315) (and (not (<= t_0 0.0)) (<= t_0 5e+306)))
     t_0
     (* (/ a1 b1) (/ a2 b2)))))
double code(double a1, double a2, double b1, double b2) {
	double t_0 = (a1 * a2) / (b1 * b2);
	double tmp;
	if ((t_0 <= -1e-315) || (!(t_0 <= 0.0) && (t_0 <= 5e+306))) {
		tmp = t_0;
	} else {
		tmp = (a1 / b1) * (a2 / b2);
	}
	return tmp;
}
real(8) function code(a1, a2, b1, b2)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2
    real(8), intent (in) :: b1
    real(8), intent (in) :: b2
    real(8) :: t_0
    real(8) :: tmp
    t_0 = (a1 * a2) / (b1 * b2)
    if ((t_0 <= (-1d-315)) .or. (.not. (t_0 <= 0.0d0)) .and. (t_0 <= 5d+306)) then
        tmp = t_0
    else
        tmp = (a1 / b1) * (a2 / b2)
    end if
    code = tmp
end function
public static double code(double a1, double a2, double b1, double b2) {
	double t_0 = (a1 * a2) / (b1 * b2);
	double tmp;
	if ((t_0 <= -1e-315) || (!(t_0 <= 0.0) && (t_0 <= 5e+306))) {
		tmp = t_0;
	} else {
		tmp = (a1 / b1) * (a2 / b2);
	}
	return tmp;
}
def code(a1, a2, b1, b2):
	t_0 = (a1 * a2) / (b1 * b2)
	tmp = 0
	if (t_0 <= -1e-315) or (not (t_0 <= 0.0) and (t_0 <= 5e+306)):
		tmp = t_0
	else:
		tmp = (a1 / b1) * (a2 / b2)
	return tmp
function code(a1, a2, b1, b2)
	t_0 = Float64(Float64(a1 * a2) / Float64(b1 * b2))
	tmp = 0.0
	if ((t_0 <= -1e-315) || (!(t_0 <= 0.0) && (t_0 <= 5e+306)))
		tmp = t_0;
	else
		tmp = Float64(Float64(a1 / b1) * Float64(a2 / b2));
	end
	return tmp
end
function tmp_2 = code(a1, a2, b1, b2)
	t_0 = (a1 * a2) / (b1 * b2);
	tmp = 0.0;
	if ((t_0 <= -1e-315) || (~((t_0 <= 0.0)) && (t_0 <= 5e+306)))
		tmp = t_0;
	else
		tmp = (a1 / b1) * (a2 / b2);
	end
	tmp_2 = tmp;
end
code[a1_, a2_, b1_, b2_] := Block[{t$95$0 = N[(N[(a1 * a2), $MachinePrecision] / N[(b1 * b2), $MachinePrecision]), $MachinePrecision]}, If[Or[LessEqual[t$95$0, -1e-315], And[N[Not[LessEqual[t$95$0, 0.0]], $MachinePrecision], LessEqual[t$95$0, 5e+306]]], t$95$0, N[(N[(a1 / b1), $MachinePrecision] * N[(a2 / b2), $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}

\\
\begin{array}{l}
t_0 := \frac{a1 \cdot a2}{b1 \cdot b2}\\
\mathbf{if}\;t_0 \leq -1 \cdot 10^{-315} \lor \neg \left(t_0 \leq 0\right) \land t_0 \leq 5 \cdot 10^{+306}:\\
\;\;\;\;t_0\\

\mathbf{else}:\\
\;\;\;\;\frac{a1}{b1} \cdot \frac{a2}{b2}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (/.f64 (*.f64 a1 a2) (*.f64 b1 b2)) < -9.999999985e-316 or 0.0 < (/.f64 (*.f64 a1 a2) (*.f64 b1 b2)) < 4.99999999999999993e306

    1. Initial program 95.7%

      \[\frac{a1 \cdot a2}{b1 \cdot b2} \]

    if -9.999999985e-316 < (/.f64 (*.f64 a1 a2) (*.f64 b1 b2)) < 0.0 or 4.99999999999999993e306 < (/.f64 (*.f64 a1 a2) (*.f64 b1 b2))

    1. Initial program 68.6%

      \[\frac{a1 \cdot a2}{b1 \cdot b2} \]
    2. Step-by-step derivation
      1. times-frac98.3%

        \[\leadsto \color{blue}{\frac{a1}{b1} \cdot \frac{a2}{b2}} \]
    3. Simplified98.3%

      \[\leadsto \color{blue}{\frac{a1}{b1} \cdot \frac{a2}{b2}} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification96.8%

    \[\leadsto \begin{array}{l} \mathbf{if}\;\frac{a1 \cdot a2}{b1 \cdot b2} \leq -1 \cdot 10^{-315} \lor \neg \left(\frac{a1 \cdot a2}{b1 \cdot b2} \leq 0\right) \land \frac{a1 \cdot a2}{b1 \cdot b2} \leq 5 \cdot 10^{+306}:\\ \;\;\;\;\frac{a1 \cdot a2}{b1 \cdot b2}\\ \mathbf{else}:\\ \;\;\;\;\frac{a1}{b1} \cdot \frac{a2}{b2}\\ \end{array} \]

Alternative 3: 86.0% accurate, 0.6× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;b2 \leq -7.6 \cdot 10^{+83}:\\ \;\;\;\;\frac{a1}{\frac{b1 \cdot b2}{a2}}\\ \mathbf{elif}\;b2 \leq -8.6 \cdot 10^{-267}:\\ \;\;\;\;\frac{a1}{b1} \cdot \frac{a2}{b2}\\ \mathbf{else}:\\ \;\;\;\;\frac{a1}{\frac{b2}{\frac{a2}{b1}}}\\ \end{array} \end{array} \]
(FPCore (a1 a2 b1 b2)
 :precision binary64
 (if (<= b2 -7.6e+83)
   (/ a1 (/ (* b1 b2) a2))
   (if (<= b2 -8.6e-267) (* (/ a1 b1) (/ a2 b2)) (/ a1 (/ b2 (/ a2 b1))))))
double code(double a1, double a2, double b1, double b2) {
	double tmp;
	if (b2 <= -7.6e+83) {
		tmp = a1 / ((b1 * b2) / a2);
	} else if (b2 <= -8.6e-267) {
		tmp = (a1 / b1) * (a2 / b2);
	} else {
		tmp = a1 / (b2 / (a2 / b1));
	}
	return tmp;
}
real(8) function code(a1, a2, b1, b2)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2
    real(8), intent (in) :: b1
    real(8), intent (in) :: b2
    real(8) :: tmp
    if (b2 <= (-7.6d+83)) then
        tmp = a1 / ((b1 * b2) / a2)
    else if (b2 <= (-8.6d-267)) then
        tmp = (a1 / b1) * (a2 / b2)
    else
        tmp = a1 / (b2 / (a2 / b1))
    end if
    code = tmp
end function
public static double code(double a1, double a2, double b1, double b2) {
	double tmp;
	if (b2 <= -7.6e+83) {
		tmp = a1 / ((b1 * b2) / a2);
	} else if (b2 <= -8.6e-267) {
		tmp = (a1 / b1) * (a2 / b2);
	} else {
		tmp = a1 / (b2 / (a2 / b1));
	}
	return tmp;
}
def code(a1, a2, b1, b2):
	tmp = 0
	if b2 <= -7.6e+83:
		tmp = a1 / ((b1 * b2) / a2)
	elif b2 <= -8.6e-267:
		tmp = (a1 / b1) * (a2 / b2)
	else:
		tmp = a1 / (b2 / (a2 / b1))
	return tmp
function code(a1, a2, b1, b2)
	tmp = 0.0
	if (b2 <= -7.6e+83)
		tmp = Float64(a1 / Float64(Float64(b1 * b2) / a2));
	elseif (b2 <= -8.6e-267)
		tmp = Float64(Float64(a1 / b1) * Float64(a2 / b2));
	else
		tmp = Float64(a1 / Float64(b2 / Float64(a2 / b1)));
	end
	return tmp
end
function tmp_2 = code(a1, a2, b1, b2)
	tmp = 0.0;
	if (b2 <= -7.6e+83)
		tmp = a1 / ((b1 * b2) / a2);
	elseif (b2 <= -8.6e-267)
		tmp = (a1 / b1) * (a2 / b2);
	else
		tmp = a1 / (b2 / (a2 / b1));
	end
	tmp_2 = tmp;
end
code[a1_, a2_, b1_, b2_] := If[LessEqual[b2, -7.6e+83], N[(a1 / N[(N[(b1 * b2), $MachinePrecision] / a2), $MachinePrecision]), $MachinePrecision], If[LessEqual[b2, -8.6e-267], N[(N[(a1 / b1), $MachinePrecision] * N[(a2 / b2), $MachinePrecision]), $MachinePrecision], N[(a1 / N[(b2 / N[(a2 / b1), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;b2 \leq -7.6 \cdot 10^{+83}:\\
\;\;\;\;\frac{a1}{\frac{b1 \cdot b2}{a2}}\\

\mathbf{elif}\;b2 \leq -8.6 \cdot 10^{-267}:\\
\;\;\;\;\frac{a1}{b1} \cdot \frac{a2}{b2}\\

\mathbf{else}:\\
\;\;\;\;\frac{a1}{\frac{b2}{\frac{a2}{b1}}}\\


\end{array}
\end{array}
Derivation
  1. Split input into 3 regimes
  2. if b2 < -7.6000000000000004e83

    1. Initial program 90.2%

      \[\frac{a1 \cdot a2}{b1 \cdot b2} \]
    2. Step-by-step derivation
      1. associate-/l*88.8%

        \[\leadsto \color{blue}{\frac{a1}{\frac{b1 \cdot b2}{a2}}} \]
      2. *-commutative88.8%

        \[\leadsto \frac{a1}{\frac{\color{blue}{b2 \cdot b1}}{a2}} \]
      3. associate-/l*85.1%

        \[\leadsto \frac{a1}{\color{blue}{\frac{b2}{\frac{a2}{b1}}}} \]
    3. Simplified85.1%

      \[\leadsto \color{blue}{\frac{a1}{\frac{b2}{\frac{a2}{b1}}}} \]
    4. Taylor expanded in b2 around 0 88.8%

      \[\leadsto \frac{a1}{\color{blue}{\frac{b2 \cdot b1}{a2}}} \]

    if -7.6000000000000004e83 < b2 < -8.5999999999999992e-267

    1. Initial program 82.4%

      \[\frac{a1 \cdot a2}{b1 \cdot b2} \]
    2. Step-by-step derivation
      1. times-frac91.3%

        \[\leadsto \color{blue}{\frac{a1}{b1} \cdot \frac{a2}{b2}} \]
    3. Simplified91.3%

      \[\leadsto \color{blue}{\frac{a1}{b1} \cdot \frac{a2}{b2}} \]

    if -8.5999999999999992e-267 < b2

    1. Initial program 81.3%

      \[\frac{a1 \cdot a2}{b1 \cdot b2} \]
    2. Step-by-step derivation
      1. associate-/l*84.5%

        \[\leadsto \color{blue}{\frac{a1}{\frac{b1 \cdot b2}{a2}}} \]
      2. *-commutative84.5%

        \[\leadsto \frac{a1}{\frac{\color{blue}{b2 \cdot b1}}{a2}} \]
      3. associate-/l*89.8%

        \[\leadsto \frac{a1}{\color{blue}{\frac{b2}{\frac{a2}{b1}}}} \]
    3. Simplified89.8%

      \[\leadsto \color{blue}{\frac{a1}{\frac{b2}{\frac{a2}{b1}}}} \]
  3. Recombined 3 regimes into one program.
  4. Final simplification90.1%

    \[\leadsto \begin{array}{l} \mathbf{if}\;b2 \leq -7.6 \cdot 10^{+83}:\\ \;\;\;\;\frac{a1}{\frac{b1 \cdot b2}{a2}}\\ \mathbf{elif}\;b2 \leq -8.6 \cdot 10^{-267}:\\ \;\;\;\;\frac{a1}{b1} \cdot \frac{a2}{b2}\\ \mathbf{else}:\\ \;\;\;\;\frac{a1}{\frac{b2}{\frac{a2}{b1}}}\\ \end{array} \]

Alternative 4: 86.4% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{a1}{b1} \cdot \frac{a2}{b2} \end{array} \]
(FPCore (a1 a2 b1 b2) :precision binary64 (* (/ a1 b1) (/ a2 b2)))
double code(double a1, double a2, double b1, double b2) {
	return (a1 / b1) * (a2 / b2);
}
real(8) function code(a1, a2, b1, b2)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2
    real(8), intent (in) :: b1
    real(8), intent (in) :: b2
    code = (a1 / b1) * (a2 / b2)
end function
public static double code(double a1, double a2, double b1, double b2) {
	return (a1 / b1) * (a2 / b2);
}
def code(a1, a2, b1, b2):
	return (a1 / b1) * (a2 / b2)
function code(a1, a2, b1, b2)
	return Float64(Float64(a1 / b1) * Float64(a2 / b2))
end
function tmp = code(a1, a2, b1, b2)
	tmp = (a1 / b1) * (a2 / b2);
end
code[a1_, a2_, b1_, b2_] := N[(N[(a1 / b1), $MachinePrecision] * N[(a2 / b2), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{a1}{b1} \cdot \frac{a2}{b2}
\end{array}
Derivation
  1. Initial program 83.4%

    \[\frac{a1 \cdot a2}{b1 \cdot b2} \]
  2. Step-by-step derivation
    1. times-frac84.6%

      \[\leadsto \color{blue}{\frac{a1}{b1} \cdot \frac{a2}{b2}} \]
  3. Simplified84.6%

    \[\leadsto \color{blue}{\frac{a1}{b1} \cdot \frac{a2}{b2}} \]
  4. Final simplification84.6%

    \[\leadsto \frac{a1}{b1} \cdot \frac{a2}{b2} \]

Alternative 5: 86.0% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{a1}{\frac{b2}{\frac{a2}{b1}}} \end{array} \]
(FPCore (a1 a2 b1 b2) :precision binary64 (/ a1 (/ b2 (/ a2 b1))))
double code(double a1, double a2, double b1, double b2) {
	return a1 / (b2 / (a2 / b1));
}
real(8) function code(a1, a2, b1, b2)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2
    real(8), intent (in) :: b1
    real(8), intent (in) :: b2
    code = a1 / (b2 / (a2 / b1))
end function
public static double code(double a1, double a2, double b1, double b2) {
	return a1 / (b2 / (a2 / b1));
}
def code(a1, a2, b1, b2):
	return a1 / (b2 / (a2 / b1))
function code(a1, a2, b1, b2)
	return Float64(a1 / Float64(b2 / Float64(a2 / b1)))
end
function tmp = code(a1, a2, b1, b2)
	tmp = a1 / (b2 / (a2 / b1));
end
code[a1_, a2_, b1_, b2_] := N[(a1 / N[(b2 / N[(a2 / b1), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{a1}{\frac{b2}{\frac{a2}{b1}}}
\end{array}
Derivation
  1. Initial program 83.4%

    \[\frac{a1 \cdot a2}{b1 \cdot b2} \]
  2. Step-by-step derivation
    1. associate-/l*85.5%

      \[\leadsto \color{blue}{\frac{a1}{\frac{b1 \cdot b2}{a2}}} \]
    2. *-commutative85.5%

      \[\leadsto \frac{a1}{\frac{\color{blue}{b2 \cdot b1}}{a2}} \]
    3. associate-/l*87.3%

      \[\leadsto \frac{a1}{\color{blue}{\frac{b2}{\frac{a2}{b1}}}} \]
  3. Simplified87.3%

    \[\leadsto \color{blue}{\frac{a1}{\frac{b2}{\frac{a2}{b1}}}} \]
  4. Final simplification87.3%

    \[\leadsto \frac{a1}{\frac{b2}{\frac{a2}{b1}}} \]

Developer target: 86.4% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{a1}{b1} \cdot \frac{a2}{b2} \end{array} \]
(FPCore (a1 a2 b1 b2) :precision binary64 (* (/ a1 b1) (/ a2 b2)))
double code(double a1, double a2, double b1, double b2) {
	return (a1 / b1) * (a2 / b2);
}
real(8) function code(a1, a2, b1, b2)
    real(8), intent (in) :: a1
    real(8), intent (in) :: a2
    real(8), intent (in) :: b1
    real(8), intent (in) :: b2
    code = (a1 / b1) * (a2 / b2)
end function
public static double code(double a1, double a2, double b1, double b2) {
	return (a1 / b1) * (a2 / b2);
}
def code(a1, a2, b1, b2):
	return (a1 / b1) * (a2 / b2)
function code(a1, a2, b1, b2)
	return Float64(Float64(a1 / b1) * Float64(a2 / b2))
end
function tmp = code(a1, a2, b1, b2)
	tmp = (a1 / b1) * (a2 / b2);
end
code[a1_, a2_, b1_, b2_] := N[(N[(a1 / b1), $MachinePrecision] * N[(a2 / b2), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{a1}{b1} \cdot \frac{a2}{b2}
\end{array}

Reproduce

?
herbie shell --seed 2023255 
(FPCore (a1 a2 b1 b2)
  :name "Quotient of products"
  :precision binary64

  :herbie-target
  (* (/ a1 b1) (/ a2 b2))

  (/ (* a1 a2) (* b1 b2)))