Quotient of products

Percentage Accurate: 85.8% → 89.8%
Time: 3.1s
Alternatives: 3
Speedup: 1.0×

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 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: 85.8% 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: 89.8% accurate, 0.5× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;a1 \cdot a2 \leq -4 \cdot 10^{+184} \lor \neg \left(a1 \cdot a2 \leq -2 \cdot 10^{-168}\right):\\ \;\;\;\;\frac{a1}{\frac{b2}{a2} \cdot b1}\\ \mathbf{else}:\\ \;\;\;\;\frac{a1 \cdot a2}{b2 \cdot b1}\\ \end{array} \end{array} \]
(FPCore (a1 a2 b1 b2)
 :precision binary64
 (if (or (<= (* a1 a2) -4e+184) (not (<= (* a1 a2) -2e-168)))
   (/ a1 (* (/ b2 a2) b1))
   (/ (* a1 a2) (* b2 b1))))
double code(double a1, double a2, double b1, double b2) {
	double tmp;
	if (((a1 * a2) <= -4e+184) || !((a1 * a2) <= -2e-168)) {
		tmp = a1 / ((b2 / a2) * b1);
	} else {
		tmp = (a1 * a2) / (b2 * 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 (((a1 * a2) <= (-4d+184)) .or. (.not. ((a1 * a2) <= (-2d-168)))) then
        tmp = a1 / ((b2 / a2) * b1)
    else
        tmp = (a1 * a2) / (b2 * b1)
    end if
    code = tmp
end function
public static double code(double a1, double a2, double b1, double b2) {
	double tmp;
	if (((a1 * a2) <= -4e+184) || !((a1 * a2) <= -2e-168)) {
		tmp = a1 / ((b2 / a2) * b1);
	} else {
		tmp = (a1 * a2) / (b2 * b1);
	}
	return tmp;
}
def code(a1, a2, b1, b2):
	tmp = 0
	if ((a1 * a2) <= -4e+184) or not ((a1 * a2) <= -2e-168):
		tmp = a1 / ((b2 / a2) * b1)
	else:
		tmp = (a1 * a2) / (b2 * b1)
	return tmp
function code(a1, a2, b1, b2)
	tmp = 0.0
	if ((Float64(a1 * a2) <= -4e+184) || !(Float64(a1 * a2) <= -2e-168))
		tmp = Float64(a1 / Float64(Float64(b2 / a2) * b1));
	else
		tmp = Float64(Float64(a1 * a2) / Float64(b2 * b1));
	end
	return tmp
end
function tmp_2 = code(a1, a2, b1, b2)
	tmp = 0.0;
	if (((a1 * a2) <= -4e+184) || ~(((a1 * a2) <= -2e-168)))
		tmp = a1 / ((b2 / a2) * b1);
	else
		tmp = (a1 * a2) / (b2 * b1);
	end
	tmp_2 = tmp;
end
code[a1_, a2_, b1_, b2_] := If[Or[LessEqual[N[(a1 * a2), $MachinePrecision], -4e+184], N[Not[LessEqual[N[(a1 * a2), $MachinePrecision], -2e-168]], $MachinePrecision]], N[(a1 / N[(N[(b2 / a2), $MachinePrecision] * b1), $MachinePrecision]), $MachinePrecision], N[(N[(a1 * a2), $MachinePrecision] / N[(b2 * b1), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;a1 \cdot a2 \leq -4 \cdot 10^{+184} \lor \neg \left(a1 \cdot a2 \leq -2 \cdot 10^{-168}\right):\\
\;\;\;\;\frac{a1}{\frac{b2}{a2} \cdot b1}\\

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


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (*.f64 a1 a2) < -4.00000000000000007e184 or -2.0000000000000001e-168 < (*.f64 a1 a2)

    1. Initial program 81.4%

      \[\frac{a1 \cdot a2}{b1 \cdot b2} \]
    2. Step-by-step derivation
      1. times-frac92.0%

        \[\leadsto \color{blue}{\frac{a1}{b1} \cdot \frac{a2}{b2}} \]
      2. *-commutative92.0%

        \[\leadsto \color{blue}{\frac{a2}{b2} \cdot \frac{a1}{b1}} \]
    3. Simplified92.0%

      \[\leadsto \color{blue}{\frac{a2}{b2} \cdot \frac{a1}{b1}} \]
    4. Step-by-step derivation
      1. clear-num92.0%

        \[\leadsto \color{blue}{\frac{1}{\frac{b2}{a2}}} \cdot \frac{a1}{b1} \]
      2. frac-times95.3%

        \[\leadsto \color{blue}{\frac{1 \cdot a1}{\frac{b2}{a2} \cdot b1}} \]
      3. *-un-lft-identity95.3%

        \[\leadsto \frac{\color{blue}{a1}}{\frac{b2}{a2} \cdot b1} \]
    5. Applied egg-rr95.3%

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

    if -4.00000000000000007e184 < (*.f64 a1 a2) < -2.0000000000000001e-168

    1. Initial program 99.5%

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

    \[\leadsto \begin{array}{l} \mathbf{if}\;a1 \cdot a2 \leq -4 \cdot 10^{+184} \lor \neg \left(a1 \cdot a2 \leq -2 \cdot 10^{-168}\right):\\ \;\;\;\;\frac{a1}{\frac{b2}{a2} \cdot b1}\\ \mathbf{else}:\\ \;\;\;\;\frac{a1 \cdot a2}{b2 \cdot b1}\\ \end{array} \]

Alternative 2: 86.1% accurate, 0.8× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;a2 \leq -5 \cdot 10^{-297}:\\ \;\;\;\;a1 \cdot \frac{a2}{b2 \cdot b1}\\ \mathbf{else}:\\ \;\;\;\;\frac{a2}{b2} \cdot \frac{a1}{b1}\\ \end{array} \end{array} \]
(FPCore (a1 a2 b1 b2)
 :precision binary64
 (if (<= a2 -5e-297) (* a1 (/ a2 (* b2 b1))) (* (/ a2 b2) (/ a1 b1))))
double code(double a1, double a2, double b1, double b2) {
	double tmp;
	if (a2 <= -5e-297) {
		tmp = a1 * (a2 / (b2 * b1));
	} else {
		tmp = (a2 / b2) * (a1 / 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 (a2 <= (-5d-297)) then
        tmp = a1 * (a2 / (b2 * b1))
    else
        tmp = (a2 / b2) * (a1 / b1)
    end if
    code = tmp
end function
public static double code(double a1, double a2, double b1, double b2) {
	double tmp;
	if (a2 <= -5e-297) {
		tmp = a1 * (a2 / (b2 * b1));
	} else {
		tmp = (a2 / b2) * (a1 / b1);
	}
	return tmp;
}
def code(a1, a2, b1, b2):
	tmp = 0
	if a2 <= -5e-297:
		tmp = a1 * (a2 / (b2 * b1))
	else:
		tmp = (a2 / b2) * (a1 / b1)
	return tmp
function code(a1, a2, b1, b2)
	tmp = 0.0
	if (a2 <= -5e-297)
		tmp = Float64(a1 * Float64(a2 / Float64(b2 * b1)));
	else
		tmp = Float64(Float64(a2 / b2) * Float64(a1 / b1));
	end
	return tmp
end
function tmp_2 = code(a1, a2, b1, b2)
	tmp = 0.0;
	if (a2 <= -5e-297)
		tmp = a1 * (a2 / (b2 * b1));
	else
		tmp = (a2 / b2) * (a1 / b1);
	end
	tmp_2 = tmp;
end
code[a1_, a2_, b1_, b2_] := If[LessEqual[a2, -5e-297], N[(a1 * N[(a2 / N[(b2 * b1), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(N[(a2 / b2), $MachinePrecision] * N[(a1 / b1), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;a2 \leq -5 \cdot 10^{-297}:\\
\;\;\;\;a1 \cdot \frac{a2}{b2 \cdot b1}\\

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


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if a2 < -5e-297

    1. Initial program 91.4%

      \[\frac{a1 \cdot a2}{b1 \cdot b2} \]
    2. Step-by-step derivation
      1. times-frac85.8%

        \[\leadsto \color{blue}{\frac{a1}{b1} \cdot \frac{a2}{b2}} \]
      2. *-commutative85.8%

        \[\leadsto \color{blue}{\frac{a2}{b2} \cdot \frac{a1}{b1}} \]
    3. Simplified85.8%

      \[\leadsto \color{blue}{\frac{a2}{b2} \cdot \frac{a1}{b1}} \]
    4. Taylor expanded in a2 around 0 91.4%

      \[\leadsto \color{blue}{\frac{a1 \cdot a2}{b1 \cdot b2}} \]
    5. Step-by-step derivation
      1. *-commutative91.4%

        \[\leadsto \frac{a1 \cdot a2}{\color{blue}{b2 \cdot b1}} \]
      2. associate-*r/92.8%

        \[\leadsto \color{blue}{a1 \cdot \frac{a2}{b2 \cdot b1}} \]
      3. *-commutative92.8%

        \[\leadsto a1 \cdot \frac{a2}{\color{blue}{b1 \cdot b2}} \]
    6. Simplified92.8%

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

    if -5e-297 < a2

    1. Initial program 81.1%

      \[\frac{a1 \cdot a2}{b1 \cdot b2} \]
    2. Step-by-step derivation
      1. times-frac94.7%

        \[\leadsto \color{blue}{\frac{a1}{b1} \cdot \frac{a2}{b2}} \]
      2. *-commutative94.7%

        \[\leadsto \color{blue}{\frac{a2}{b2} \cdot \frac{a1}{b1}} \]
    3. Simplified94.7%

      \[\leadsto \color{blue}{\frac{a2}{b2} \cdot \frac{a1}{b1}} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification93.7%

    \[\leadsto \begin{array}{l} \mathbf{if}\;a2 \leq -5 \cdot 10^{-297}:\\ \;\;\;\;a1 \cdot \frac{a2}{b2 \cdot b1}\\ \mathbf{else}:\\ \;\;\;\;\frac{a2}{b2} \cdot \frac{a1}{b1}\\ \end{array} \]

Alternative 3: 86.7% accurate, 1.0× speedup?

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

\\
a1 \cdot \frac{a2}{b2 \cdot b1}
\end{array}
Derivation
  1. Initial program 86.2%

    \[\frac{a1 \cdot a2}{b1 \cdot b2} \]
  2. Step-by-step derivation
    1. times-frac90.3%

      \[\leadsto \color{blue}{\frac{a1}{b1} \cdot \frac{a2}{b2}} \]
    2. *-commutative90.3%

      \[\leadsto \color{blue}{\frac{a2}{b2} \cdot \frac{a1}{b1}} \]
  3. Simplified90.3%

    \[\leadsto \color{blue}{\frac{a2}{b2} \cdot \frac{a1}{b1}} \]
  4. Taylor expanded in a2 around 0 86.2%

    \[\leadsto \color{blue}{\frac{a1 \cdot a2}{b1 \cdot b2}} \]
  5. Step-by-step derivation
    1. *-commutative86.2%

      \[\leadsto \frac{a1 \cdot a2}{\color{blue}{b2 \cdot b1}} \]
    2. associate-*r/89.0%

      \[\leadsto \color{blue}{a1 \cdot \frac{a2}{b2 \cdot b1}} \]
    3. *-commutative89.0%

      \[\leadsto a1 \cdot \frac{a2}{\color{blue}{b1 \cdot b2}} \]
  6. Simplified89.0%

    \[\leadsto \color{blue}{a1 \cdot \frac{a2}{b1 \cdot b2}} \]
  7. Final simplification89.0%

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

Developer target: 86.5% 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

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herbie shell --seed 2023272 
(FPCore (a1 a2 b1 b2)
  :name "Quotient of products"
  :precision binary64

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

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