\[1.0536712127723509 \cdot 10^{-08} < a \land a < 94906265.62425156 \land 1.0536712127723509 \cdot 10^{-08} < b \land b < 94906265.62425156 \land 1.0536712127723509 \cdot 10^{-08} < c \land c < 94906265.62425156\]

\[\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}\]

\frac{\left(-b\right) + \sqrt{b \cdot b - \left(3 \cdot a\right) \cdot c}}{3 \cdot a}

(FPCore (a b c)
 :precision binary64
 (/ (+ (- b) (sqrt (- (* b b) (* (* 3.0 a) c)))) (* 3.0 a)))

double code(double a, double b, double c) {
	return (-b + sqrt((b * b) - ((3.0 * a) * c))) / (3.0 * a);
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2021060 
(FPCore (a b c)
  :name "Cubic critical, narrow range"
  :precision binary64
  :pre (and (< 1.0536712127723509e-08 a 94906265.62425156) (< 1.0536712127723509e-08 b 94906265.62425156) (< 1.0536712127723509e-08 c 94906265.62425156))
  (/ (+ (- b) (sqrt (- (* b b) (* (* 3.0 a) c)))) (* 3.0 a)))

Backtrace

Failed to produce proof for (neg.f64 (-.f64 (sqrt.f64 (-.f64 (.f64 b b) (.f64 (.f64 3 a) c))) b)) to (+.f64 b (neg.f64 (sqrt.f64 (-.f64 (.f64 b b) (.f64 a (.f64 3 c))))))		L	C
for-loop	/data/pavpan/nightlies/herbie/egg-generate-proof/src/core/simplify.rkt	167	8
(unnamed)	/data/pavpan/nightlies/herbie/egg-generate-proof/src/core/simplify.rkt	149	6
egraph-add-exprs	/data/pavpan/nightlies/herbie/egg-generate-proof/egg-herbie/main.rkt	154	0
with-egraph	/data/pavpan/nightlies/herbie/egg-generate-proof/egg-herbie/main.rkt	74	0
(unnamed)	/data/pavpan/nightlies/herbie/egg-generate-proof/src/core/simplify.rkt	79	0
simplify!	/data/pavpan/nightlies/herbie/egg-generate-proof/src/mainloop.rkt	236	0
run-iter!	/data/pavpan/nightlies/herbie/egg-generate-proof/src/mainloop.rkt	360	0
run-improve	/data/pavpan/nightlies/herbie/egg-generate-proof/src/mainloop.rkt	377	0
(unnamed)	/data/pavpan/nightlies/herbie/egg-generate-proof/src/sandbox.rkt	54	6
run	/opt/racket-7.9/share/pkgs/profile-lib/main.rkt	39	2
profile-thunk	/opt/racket-7.9/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/opt/racket-7.9/collects/racket/engine.rkt	42	24