Exception for 2-ancestry mixing, negative discriminant

• Falling back on racket egraph because egg-herbie package not installed

Math

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

C

double f(double g, double h) {
        double r48105 = 2.0;
        double r48106 = atan2(1.0, 0.0);
        double r48107 = r48105 * r48106;
        double r48108 = 3.0;
        double r48109 = r48107 / r48108;
        double r48110 = g;
        double r48111 = -r48110;
        double r48112 = h;
        double r48113 = r48111 / r48112;
        double r48114 = acos(r48113);
        double r48115 = r48114 / r48108;
        double r48116 = r48109 + r48115;
        double r48117 = cos(r48116);
        double r48118 = r48105 * r48117;
        return r48118;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2020045 
(FPCore (g h)
  :name "2-ancestry mixing, negative discriminant"
  :precision binary64
  (* 2 (cos (+ (/ (* 2 PI) 3) (/ (acos (/ (- g) h)) 3)))))

Backtrace

hash-ref: no value found for key key: '(* #<enode 140(140)> #<enode 5(137)>)		L	C
for-loop	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/egraph.rkt	270	6
update-leader!	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/egraph.rkt	265	0
for-loop	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/main.rkt	77	2
prune-phase	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/main.rkt	74	0
for-loop	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/core/simplify.rkt	80	4
for-loop	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/core/simplify.rkt	76	2
(unnamed)	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/core/simplify.rkt	56	0
(unnamed)	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/core/simplify.rkt	38	0
simplify!	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/mainloop.rkt	224	0
run-iter!	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/mainloop.rkt	327	0
for-loop	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/mainloop.rkt	365	4
run-improve47	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/mainloop.rkt	346	0
.../more-scheme.rkt:261:28	unknown
run	/opt/racket-7.5/share/pkgs/profile-lib/main.rkt	39	2
profile-thunk16	/opt/racket-7.5/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/opt/racket-7.5/collects/racket/private/more-scheme.rkt	261	28