\[\frac{b \cdot c - a \cdot d}{c \cdot c + d \cdot d}\]

\frac{b \cdot c - a \cdot d}{c \cdot c + d \cdot d}

double f(double a, double b, double c, double d) {
        double r12123872 = b;
        double r12123873 = c;
        double r12123874 = r12123872 * r12123873;
        double r12123875 = a;
        double r12123876 = d;
        double r12123877 = r12123875 * r12123876;
        double r12123878 = r12123874 - r12123877;
        double r12123879 = r12123873 * r12123873;
        double r12123880 = r12123876 * r12123876;
        double r12123881 = r12123879 + r12123880;
        double r12123882 = r12123878 / r12123881;
        return r12123882;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019173 
(FPCore (a b c d)
  :name "Complex division, imag part"

  :herbie-target
  (if (< (fabs d) (fabs c)) (/ (- b (* a (/ d c))) (+ c (* d (/ d c)))) (/ (+ (- a) (* b (/ c d))) (+ d (* c (/ c d)))))

  (/ (- (* b c) (* a d)) (+ (* c c) (* d d))))

Backtrace

hash-ref: no value found for key key: #<enode 306(306)>		L	C
for-loop	/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt	197	2
extractor-extract	/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt	196	0
for-loop	/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt	35	2
(unnamed)	/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt	26	0
simplify!	/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt	217	0
run-iter!	/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt	320	0
for-loop	/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt	354	4
run-improve43	/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt	339	0
(unnamed)	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	261	28
run	/opt/racket-7.0/share/pkgs/profile-lib/main.rkt	39	2
profile-thunk16	/opt/racket-7.0/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	261	28