\[2 \cdot \cos \left(\frac{2 \cdot \pi}{3} + \frac{\cos^{-1} \left(\frac{-g}{h}\right)}{3}\right)\]

2 \cdot \cos \left(\frac{2 \cdot \pi}{3} + \frac{\cos^{-1} \left(\frac{-g}{h}\right)}{3}\right)

double f(double g, double h) {
        double r8439 = 2.0;
        double r8440 = atan2(1.0, 0.0);
        double r8441 = r8439 * r8440;
        double r8442 = 3.0;
        double r8443 = r8441 / r8442;
        double r8444 = g;
        double r8445 = -r8444;
        double r8446 = h;
        double r8447 = r8445 / r8446;
        double r8448 = acos(r8447);
        double r8449 = r8448 / r8442;
        double r8450 = r8443 + r8449;
        double r8451 = cos(r8450);
        double r8452 = r8439 * r8451;
        return r8452;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019191 
(FPCore (g h)
  :name "2-ancestry mixing, negative discriminant"
  (* 2.0 (cos (+ (/ (* 2.0 PI) 3.0) (/ (acos (/ (- g) h)) 3.0)))))

Backtrace

get-representation: Unknown representation #f		L	C
loop	/data/pavpan/nightlies/herbie/interface2/src/points.rkt	122	4
prepare-points	/data/pavpan/nightlies/herbie/interface2/src/points.rkt	146	0
setup-prog!34	/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt	67	0
run-improve43	/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt	339	0
(unnamed)	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	261	28
run	/opt/racket-7.0/share/pkgs/profile-lib/main.rkt	39	2
profile-thunk16	/opt/racket-7.0/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	261	28