\[\left(\left(x \cdot y + z \cdot z\right) + z \cdot z\right) + z \cdot z\]
\left(\left(x \cdot y + z \cdot z\right) + z \cdot z\right) + z \cdot z
double f(double x, double y, double z) {
        double r8422 = x;
        double r8423 = y;
        double r8424 = r8422 * r8423;
        double r8425 = z;
        double r8426 = r8425 * r8425;
        double r8427 = r8424 + r8426;
        double r8428 = r8427 + r8426;
        double r8429 = r8428 + r8426;
        return r8429;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019191 
(FPCore (x y z)
  :name "Linear.Quaternion:$c/ from linear-1.19.1.3, A"

  :herbie-target
  (+ (* (* 3.0 z) z) (* y x))

  (+ (+ (+ (* x y) (* z z)) (* z z)) (* z z)))

Backtrace

get-representation: Unknown representation #fLC
loop/data/pavpan/nightlies/herbie/interface2/src/points.rkt1224
prepare-points/data/pavpan/nightlies/herbie/interface2/src/points.rkt1460
setup-prog!34/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt670
run-improve43/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt3390
(unnamed)/opt/racket-7.0/collects/racket/private/more-scheme.rkt26128
run/opt/racket-7.0/share/pkgs/profile-lib/main.rkt392
profile-thunk16/opt/racket-7.0/share/pkgs/profile-lib/main.rkt90
(unnamed)/opt/racket-7.0/collects/racket/private/more-scheme.rkt26128