Average Error: 11.5 → 5.0
Time: 17.5s
Precision: 64
\[\frac{a1 \cdot a2}{b1 \cdot b2}\]
\[\begin{array}{l} \mathbf{if}\;b2 \cdot b1 \le -5.027198331468452971083277390987079564256 \cdot 10^{271}:\\ \;\;\;\;\frac{a2}{b2} \cdot \frac{a1}{b1}\\ \mathbf{elif}\;b2 \cdot b1 \le -1.708279358278811067826228393370497973053 \cdot 10^{-240}:\\ \;\;\;\;\frac{a1}{b2 \cdot b1} \cdot a2\\ \mathbf{elif}\;b2 \cdot b1 \le 2.491183802213925616452581733594161045108 \cdot 10^{-239}:\\ \;\;\;\;\frac{1}{b1} \cdot \frac{a1}{\frac{b2}{a2}}\\ \mathbf{elif}\;b2 \cdot b1 \le 3.274003468956291087635927220582233224264 \cdot 10^{201}:\\ \;\;\;\;\frac{a1}{b2 \cdot b1} \cdot a2\\ \mathbf{else}:\\ \;\;\;\;\frac{a2}{b2} \cdot \frac{a1}{b1}\\ \end{array}\]
\frac{a1 \cdot a2}{b1 \cdot b2}
\begin{array}{l}
\mathbf{if}\;b2 \cdot b1 \le -5.027198331468452971083277390987079564256 \cdot 10^{271}:\\
\;\;\;\;\frac{a2}{b2} \cdot \frac{a1}{b1}\\

\mathbf{elif}\;b2 \cdot b1 \le -1.708279358278811067826228393370497973053 \cdot 10^{-240}:\\
\;\;\;\;\frac{a1}{b2 \cdot b1} \cdot a2\\

\mathbf{elif}\;b2 \cdot b1 \le 2.491183802213925616452581733594161045108 \cdot 10^{-239}:\\
\;\;\;\;\frac{1}{b1} \cdot \frac{a1}{\frac{b2}{a2}}\\

\mathbf{elif}\;b2 \cdot b1 \le 3.274003468956291087635927220582233224264 \cdot 10^{201}:\\
\;\;\;\;\frac{a1}{b2 \cdot b1} \cdot a2\\

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

\end{array}
double f(double a1, double a2, double b1, double b2) {
        double r4521112 = a1;
        double r4521113 = a2;
        double r4521114 = r4521112 * r4521113;
        double r4521115 = b1;
        double r4521116 = b2;
        double r4521117 = r4521115 * r4521116;
        double r4521118 = r4521114 / r4521117;
        return r4521118;
}

double f(double a1, double a2, double b1, double b2) {
        double r4521119 = b2;
        double r4521120 = b1;
        double r4521121 = r4521119 * r4521120;
        double r4521122 = -5.027198331468453e+271;
        bool r4521123 = r4521121 <= r4521122;
        double r4521124 = a2;
        double r4521125 = r4521124 / r4521119;
        double r4521126 = a1;
        double r4521127 = r4521126 / r4521120;
        double r4521128 = r4521125 * r4521127;
        double r4521129 = -1.708279358278811e-240;
        bool r4521130 = r4521121 <= r4521129;
        double r4521131 = r4521126 / r4521121;
        double r4521132 = r4521131 * r4521124;
        double r4521133 = 2.4911838022139256e-239;
        bool r4521134 = r4521121 <= r4521133;
        double r4521135 = 1.0;
        double r4521136 = r4521135 / r4521120;
        double r4521137 = r4521119 / r4521124;
        double r4521138 = r4521126 / r4521137;
        double r4521139 = r4521136 * r4521138;
        double r4521140 = 3.274003468956291e+201;
        bool r4521141 = r4521121 <= r4521140;
        double r4521142 = r4521141 ? r4521132 : r4521128;
        double r4521143 = r4521134 ? r4521139 : r4521142;
        double r4521144 = r4521130 ? r4521132 : r4521143;
        double r4521145 = r4521123 ? r4521128 : r4521144;
        return r4521145;
}

Error

Bits error versus a1

Bits error versus a2

Bits error versus b1

Bits error versus b2

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Target

Original11.5
Target11.2
Herbie5.0
\[\frac{a1}{b1} \cdot \frac{a2}{b2}\]

Derivation

  1. Split input into 3 regimes
  2. if (* b1 b2) < -5.027198331468453e+271 or 3.274003468956291e+201 < (* b1 b2)

    1. Initial program 17.4

      \[\frac{a1 \cdot a2}{b1 \cdot b2}\]
    2. Using strategy rm
    3. Applied times-frac3.7

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

    if -5.027198331468453e+271 < (* b1 b2) < -1.708279358278811e-240 or 2.4911838022139256e-239 < (* b1 b2) < 3.274003468956291e+201

    1. Initial program 4.9

      \[\frac{a1 \cdot a2}{b1 \cdot b2}\]
    2. Using strategy rm
    3. Applied associate-/l*4.6

      \[\leadsto \color{blue}{\frac{a1}{\frac{b1 \cdot b2}{a2}}}\]
    4. Using strategy rm
    5. Applied associate-/r/4.9

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

    if -1.708279358278811e-240 < (* b1 b2) < 2.4911838022139256e-239

    1. Initial program 40.3

      \[\frac{a1 \cdot a2}{b1 \cdot b2}\]
    2. Using strategy rm
    3. Applied associate-/l*39.4

      \[\leadsto \color{blue}{\frac{a1}{\frac{b1 \cdot b2}{a2}}}\]
    4. Using strategy rm
    5. Applied *-un-lft-identity39.4

      \[\leadsto \frac{a1}{\frac{b1 \cdot b2}{\color{blue}{1 \cdot a2}}}\]
    6. Applied times-frac17.8

      \[\leadsto \frac{a1}{\color{blue}{\frac{b1}{1} \cdot \frac{b2}{a2}}}\]
    7. Applied *-un-lft-identity17.8

      \[\leadsto \frac{\color{blue}{1 \cdot a1}}{\frac{b1}{1} \cdot \frac{b2}{a2}}\]
    8. Applied times-frac8.9

      \[\leadsto \color{blue}{\frac{1}{\frac{b1}{1}} \cdot \frac{a1}{\frac{b2}{a2}}}\]
    9. Simplified8.9

      \[\leadsto \color{blue}{\frac{1}{b1}} \cdot \frac{a1}{\frac{b2}{a2}}\]
  3. Recombined 3 regimes into one program.
  4. Final simplification5.0

    \[\leadsto \begin{array}{l} \mathbf{if}\;b2 \cdot b1 \le -5.027198331468452971083277390987079564256 \cdot 10^{271}:\\ \;\;\;\;\frac{a2}{b2} \cdot \frac{a1}{b1}\\ \mathbf{elif}\;b2 \cdot b1 \le -1.708279358278811067826228393370497973053 \cdot 10^{-240}:\\ \;\;\;\;\frac{a1}{b2 \cdot b1} \cdot a2\\ \mathbf{elif}\;b2 \cdot b1 \le 2.491183802213925616452581733594161045108 \cdot 10^{-239}:\\ \;\;\;\;\frac{1}{b1} \cdot \frac{a1}{\frac{b2}{a2}}\\ \mathbf{elif}\;b2 \cdot b1 \le 3.274003468956291087635927220582233224264 \cdot 10^{201}:\\ \;\;\;\;\frac{a1}{b2 \cdot b1} \cdot a2\\ \mathbf{else}:\\ \;\;\;\;\frac{a2}{b2} \cdot \frac{a1}{b1}\\ \end{array}\]

Reproduce

herbie shell --seed 2019200 +o rules:numerics
(FPCore (a1 a2 b1 b2)
  :name "Quotient of products"

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

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