Exception for 2-ancestry mixing, negative discriminant

Math

\[2.0 \cdot \cos \left(\frac{2.0 \cdot \pi}{3.0} + \frac{\cos^{-1} \left(\frac{-g}{h}\right)}{3.0}\right)\]

C

double f(double g, double h) {
        double r3980791 = 2.0;
        double r3980792 = atan2(1.0, 0.0);
        double r3980793 = r3980791 * r3980792;
        double r3980794 = 3.0;
        double r3980795 = r3980793 / r3980794;
        double r3980796 = g;
        double r3980797 = -r3980796;
        double r3980798 = h;
        double r3980799 = r3980797 / r3980798;
        double r3980800 = acos(r3980799);
        double r3980801 = r3980800 / r3980794;
        double r3980802 = r3980795 + r3980801;
        double r3980803 = cos(r3980802);
        double r3980804 = r3980791 * r3980803;
        return r3980804;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019165 
(FPCore (g h)
  :name "2-ancestry mixing, negative discriminant"
  (* 2.0 (cos (+ (/ (* 2.0 PI) 3.0) (/ (acos (/ (- g) h)) 3.0)))))

Backtrace

->bf: contract violation expected: value? given: 'PI in: the 1st argument of (-> value? bigvalue?) contract from: (function ->bf) blaming: /data/pavpan/nightlies/herbie/optional-posits/src/float.rkt (assuming the contract is correct) at: /data/pavpan/nightlies/herbie/optional-posits/src/float.rkt:163.18		L	C
raise-blame-error16	/opt/racket-7.0/collects/racket/contract/private/blame.rkt	347	0
(unnamed)	/opt/racket-7.0/collects/racket/contract/private/arrow-higher-order.rkt	357	33
(unnamed)	/data/pavpan/nightlies/herbie/optional-posits/src/core/localize.rkt	22	13
hash-ref!	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	376	2
loop	/opt/racket-7.0/collects/racket/private/map.rkt	40	19
parse-loop15	/opt/racket-7.0/collects/racket/match/compiler.rkt	418	15
hash-ref!	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	376	2
loop	/opt/racket-7.0/collects/racket/private/map.rkt	40	19
parse-loop15	/opt/racket-7.0/collects/racket/match/compiler.rkt	418	15
hash-ref!	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	376	2
loop	/opt/racket-7.0/collects/racket/private/map.rkt	40	19
parse-loop15	/opt/racket-7.0/collects/racket/match/compiler.rkt	418	15
hash-ref!	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	376	2
map	/opt/racket-7.0/collects/racket/private/map.rkt	35	13
f9	/opt/racket-7.0/collects/racket/match/compiler.rkt	507	40
hash-ref!	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	376	2
loop	/opt/racket-7.0/collects/racket/private/map.rkt	40	19
parse-loop15	/opt/racket-7.0/collects/racket/match/compiler.rkt	418	15
hash-ref!	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	376	2
localize-error	/data/pavpan/nightlies/herbie/optional-posits/src/core/localize.rkt	52	0
localize!	/data/pavpan/nightlies/herbie/optional-posits/src/mainloop.rkt	116	0
run-iter!	/data/pavpan/nightlies/herbie/optional-posits/src/mainloop.rkt	317	0
for-loop	/data/pavpan/nightlies/herbie/optional-posits/src/mainloop.rkt	351	4
run-improve40	/data/pavpan/nightlies/herbie/optional-posits/src/mainloop.rkt	336	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