\[x - \frac{y - z}{\frac{\left(t - z\right) + 1}{a}}\]
x - \frac{y - z}{\frac{\left(t - z\right) + 1}{a}}
double f(double x, double y, double z, double t, double a) {
        double r188979 = x;
        double r188980 = y;
        double r188981 = z;
        double r188982 = r188980 - r188981;
        double r188983 = t;
        double r188984 = r188983 - r188981;
        double r188985 = 1.0;
        double r188986 = r188984 + r188985;
        double r188987 = a;
        double r188988 = r188986 / r188987;
        double r188989 = r188982 / r188988;
        double r188990 = r188979 - r188989;
        return r188990;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2020045 
(FPCore (x y z t a)
  :name "Graphics.Rendering.Chart.SparkLine:renderSparkLine from Chart-1.5.3"
  :precision binary64

  :herbie-target
  (- x (* (/ (- y z) (+ (- t z) 1)) a))

  (- x (/ (- y z) (/ (+ (- t z) 1) a))))

Backtrace

hash-ref: no value found for key key: '(+ #<enode 0(537)> #<enode 265(265)>)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