\[\frac{4 \cdot \left(\left(x - y\right) - z \cdot 0.5\right)}{z}\]
\frac{4 \cdot \left(\left(x - y\right) - z \cdot 0.5\right)}{z}
double f(double x, double y, double z) {
        double r9394 = 4.0;
        double r9395 = x;
        double r9396 = y;
        double r9397 = r9395 - r9396;
        double r9398 = z;
        double r9399 = 0.5;
        double r9400 = r9398 * r9399;
        double r9401 = r9397 - r9400;
        double r9402 = r9394 * r9401;
        double r9403 = r9402 / r9398;
        return r9403;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019305 
(FPCore (x y z)
  :name "Data.Array.Repa.Algorithms.ColorRamp:rampColorHotToCold from repa-algorithms-3.4.0.1, B"
  :precision binary64

  :herbie-target
  (- (* 4 (/ x z)) (+ 2 (* 4 (/ y z))))

  (/ (* 4 (- (- x y) (* z 0.5))) z))

Backtrace

hash-ref: no value found for key key: 4.0LC
for-loop/data/pavpan/nightlies/herbie/eggmath-testversion/src/core/eggmath.rkt706
egg-parsed->expr/data/pavpan/nightlies/herbie/eggmath-testversion/src/core/eggmath.rkt650
for-loop/data/pavpan/nightlies/herbie/eggmath-testversion/src/core/eggmath.rkt706
egg-parsed->expr/data/pavpan/nightlies/herbie/eggmath-testversion/src/core/eggmath.rkt650
(unnamed)/data/pavpan/nightlies/herbie/eggmath-testversion/src/core/simplify.rkt498
egraph-add-exprs/data/pavpan/nightlies/herbie/eggmath-testversion/src/core/eggmath.rkt1220
egraph-run/data/pavpan/nightlies/herbie/eggmath-testversion/src/core/eggmath.rkt550
(unnamed)/data/pavpan/nightlies/herbie/eggmath-testversion/src/core/simplify.rkt380
simplify!/data/pavpan/nightlies/herbie/eggmath-testversion/src/mainloop.rkt2230
run-improve47/data/pavpan/nightlies/herbie/eggmath-testversion/src/mainloop.rkt3450
(unnamed)/opt/racket-7.2/collects/racket/private/more-scheme.rkt26128
run/opt/racket-7.2/share/pkgs/profile-lib/main.rkt392
profile-thunk16/opt/racket-7.2/share/pkgs/profile-lib/main.rkt90
(unnamed)/opt/racket-7.2/collects/racket/private/more-scheme.rkt26128