\[\frac{1}{x + 1} - \frac{1}{x - 1}\]
\frac{1}{x + 1} - \frac{1}{x - 1}
double f(double x) {
        double r44608 = 1.0;
        double r44609 = x;
        double r44610 = r44609 + r44608;
        double r44611 = r44608 / r44610;
        double r44612 = r44609 - r44608;
        double r44613 = r44608 / r44612;
        double r44614 = r44611 - r44613;
        return r44614;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2020045 
(FPCore (x)
  :name "Asymptote A"
  :precision binary64
  (- (/ 1 (+ x 1)) (/ 1 (- x 1))))

Backtrace

hash-ref: no value found for key key: '(* #<enode 0(92)> #<enode 64(64)>)LC
for-loop/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/egraph.rkt2706
update-leader!/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/egraph.rkt2650
for-loop/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/main.rkt772
prune-phase/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/main.rkt740
for-loop/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/core/simplify.rkt804
for-loop/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/core/simplify.rkt762
(unnamed)/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/core/simplify.rkt560
(unnamed)/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/core/simplify.rkt380
simplify!/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/mainloop.rkt2240
run-iter!/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/mainloop.rkt3270
for-loop/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/mainloop.rkt3654
run-improve47/data/pavpan/nightlies/herbie/simplify-upwards-no-duplicates/src/mainloop.rkt3460
.../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