\[\frac{b \cdot c - a \cdot d}{c \cdot c + d \cdot d}\]
\frac{b \cdot c - a \cdot d}{c \cdot c + d \cdot d}
double code(double a, double b, double c, double d) {
	return ((double) (((double) (((double) (b * c)) - ((double) (a * d)))) / ((double) (((double) (c * c)) + ((double) (d * d))))));
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2020165 
(FPCore (a b c d)
  :name "Complex division, imag part"
  :precision binary64

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

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

Backtrace

ival-hi: contract violation expected: ival? given: #<procedure:interval>LC
for-loop/data/pavpan/nightlies/herbie/ival-find-range/src/sampling.rkt3711
hyperrect-weight/data/pavpan/nightlies/herbie/ival-find-range/src/sampling.rkt360
total-weight/data/pavpan/nightlies/herbie/ival-find-range/src/sampling.rkt1132
log-space-improvement/data/pavpan/nightlies/herbie/ival-find-range/src/sampling.rkt1100
(unnamed)/opt/racket-7.5/collects/racket/contract/private/arrow-higher-order.rkt37533
get-hyperrects/data/pavpan/nightlies/herbie/ival-find-range/src/sampling.rkt1230
make-sampler/data/pavpan/nightlies/herbie/ival-find-range/src/sampling.rkt1470
prepare-points-intervals/data/pavpan/nightlies/herbie/ival-find-range/src/points.rkt900
run-improve47/data/pavpan/nightlies/herbie/ival-find-range/src/mainloop.rkt3650
.../more-scheme.rkt:261:28unknown
run/opt/racket-7.5/share/pkgs/profile-lib/main.rkt392
profile-thunk16/opt/racket-7.5/share/pkgs/profile-lib/main.rkt90
(unnamed)/opt/racket-7.5/collects/racket/private/more-scheme.rkt26128

Reproduce

herbie shell --seed 2020165 
(FPCore (a b c d)
  :name "Complex division, imag part"
  :precision binary64

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

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