\[1 \le y \le 9999\]
\[\begin{array}{l} \mathbf{if}\;\left(\left|y - \sqrt{y \cdot y + 1}\right| - \frac{1}{y + \sqrt{y \cdot y + 1}}\right) \cdot \left(\left|y - \sqrt{y \cdot y + 1}\right| - \frac{1}{y + \sqrt{y \cdot y + 1}}\right) + {\left({10}^{-300}\right)}^{\left(10^{4} \cdot \left(y + 1\right)\right)} = 0.0:\\ \;\;\;\;1\\ \mathbf{else}:\\ \;\;\;\;\frac{e^{\left(\left|y - \sqrt{y \cdot y + 1}\right| - \frac{1}{y + \sqrt{y \cdot y + 1}}\right) \cdot \left(\left|y - \sqrt{y \cdot y + 1}\right| - \frac{1}{y + \sqrt{y \cdot y + 1}}\right) + {\left({10}^{-300}\right)}^{\left(10^{4} \cdot \left(y + 1\right)\right)}} - 1}{\left(\left|y - \sqrt{y \cdot y + 1}\right| - \frac{1}{y + \sqrt{y \cdot y + 1}}\right) \cdot \left(\left|y - \sqrt{y \cdot y + 1}\right| - \frac{1}{y + \sqrt{y \cdot y + 1}}\right) + {\left({10}^{-300}\right)}^{\left(10^{4} \cdot \left(y + 1\right)\right)}}\\ \end{array}\]
\begin{array}{l}
\mathbf{if}\;\left(\left|y - \sqrt{y \cdot y + 1}\right| - \frac{1}{y + \sqrt{y \cdot y + 1}}\right) \cdot \left(\left|y - \sqrt{y \cdot y + 1}\right| - \frac{1}{y + \sqrt{y \cdot y + 1}}\right) + {\left({10}^{-300}\right)}^{\left(10^{4} \cdot \left(y + 1\right)\right)} = 0.0:\\
\;\;\;\;1\\

\mathbf{else}:\\
\;\;\;\;\frac{e^{\left(\left|y - \sqrt{y \cdot y + 1}\right| - \frac{1}{y + \sqrt{y \cdot y + 1}}\right) \cdot \left(\left|y - \sqrt{y \cdot y + 1}\right| - \frac{1}{y + \sqrt{y \cdot y + 1}}\right) + {\left({10}^{-300}\right)}^{\left(10^{4} \cdot \left(y + 1\right)\right)}} - 1}{\left(\left|y - \sqrt{y \cdot y + 1}\right| - \frac{1}{y + \sqrt{y \cdot y + 1}}\right) \cdot \left(\left|y - \sqrt{y \cdot y + 1}\right| - \frac{1}{y + \sqrt{y \cdot y + 1}}\right) + {\left({10}^{-300}\right)}^{\left(10^{4} \cdot \left(y + 1\right)\right)}}\\

\end{array}
double f(double y) {
        double r8092 = y;
        double r8093 = r8092 * r8092;
        double r8094 = 1.0;
        double r8095 = r8093 + r8094;
        double r8096 = sqrt(r8095);
        double r8097 = r8092 - r8096;
        double r8098 = fabs(r8097);
        double r8099 = r8092 + r8096;
        double r8100 = r8094 / r8099;
        double r8101 = r8098 - r8100;
        double r8102 = r8101 * r8101;
        double r8103 = 10.0;
        double r8104 = -300.0;
        double r8105 = pow(r8103, r8104);
        double r8106 = 10000.0;
        double r8107 = r8092 + r8094;
        double r8108 = r8106 * r8107;
        double r8109 = pow(r8105, r8108);
        double r8110 = r8102 + r8109;
        double r8111 = 0.0;
        double r8112 = r8110 == r8111;
        double r8113 = exp(r8110);
        double r8114 = r8113 - r8094;
        double r8115 = r8114 / r8110;
        double r8116 = r8112 ? r8094 : r8115;
        return r8116;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019191 +o rules:numerics
(FPCore (y)
  :name "Kahan's Unum-Targeted Monster"
  :pre (<= 1.0 y 9999.0)
  (if (== (+ (* (- (fabs (- y (sqrt (+ (* y y) 1.0)))) (/ 1.0 (+ y (sqrt (+ (* y y) 1.0))))) (- (fabs (- y (sqrt (+ (* y y) 1.0)))) (/ 1.0 (+ y (sqrt (+ (* y y) 1.0)))))) (pow (pow 10.0 -300.0) (* 10000.0 (+ y 1.0)))) 0.0) 1.0 (/ (- (exp (+ (* (- (fabs (- y (sqrt (+ (* y y) 1.0)))) (/ 1.0 (+ y (sqrt (+ (* y y) 1.0))))) (- (fabs (- y (sqrt (+ (* y y) 1.0)))) (/ 1.0 (+ y (sqrt (+ (* y y) 1.0)))))) (pow (pow 10.0 -300.0) (* 10000.0 (+ y 1.0))))) 1.0) (+ (* (- (fabs (- y (sqrt (+ (* y y) 1.0)))) (/ 1.0 (+ y (sqrt (+ (* y y) 1.0))))) (- (fabs (- y (sqrt (+ (* y y) 1.0)))) (/ 1.0 (+ y (sqrt (+ (* y y) 1.0)))))) (pow (pow 10.0 -300.0) (* 10000.0 (+ y 1.0)))))))

Backtrace

get-representation: Unknown representation #fLC
loop/data/pavpan/nightlies/herbie/interface2/src/points.rkt1224
prepare-points/data/pavpan/nightlies/herbie/interface2/src/points.rkt1460
setup-prog!34/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt670
run-improve43/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt3390
(unnamed)/opt/racket-7.0/collects/racket/private/more-scheme.rkt26128
run/opt/racket-7.0/share/pkgs/profile-lib/main.rkt392
profile-thunk16/opt/racket-7.0/share/pkgs/profile-lib/main.rkt90
(unnamed)/opt/racket-7.0/collects/racket/private/more-scheme.rkt26128