\[\begin{array}{l} \mathbf{if}\;b \ge 0.0:\\ \;\;\;\;\frac{2 \cdot c}{\left(-b\right) - \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}\\ \mathbf{else}:\\ \;\;\;\;\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a}\\ \end{array}\]

\begin{array}{l}
\mathbf{if}\;b \ge 0.0:\\
\;\;\;\;\frac{2 \cdot c}{\left(-b\right) - \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}\\

\mathbf{else}:\\
\;\;\;\;\frac{\left(-b\right) + \sqrt{b \cdot b - \left(4 \cdot a\right) \cdot c}}{2 \cdot a}\\

\end{array}

double f(double a, double b, double c) {
        double r8983 = b;
        double r8984 = 0.0;
        bool r8985 = r8983 >= r8984;
        double r8986 = 2.0;
        double r8987 = c;
        double r8988 = r8986 * r8987;
        double r8989 = -r8983;
        double r8990 = r8983 * r8983;
        double r8991 = 4.0;
        double r8992 = a;
        double r8993 = r8991 * r8992;
        double r8994 = r8993 * r8987;
        double r8995 = r8990 - r8994;
        double r8996 = sqrt(r8995);
        double r8997 = r8989 - r8996;
        double r8998 = r8988 / r8997;
        double r8999 = r8989 + r8996;
        double r9000 = r8986 * r8992;
        double r9001 = r8999 / r9000;
        double r9002 = r8985 ? r8998 : r9001;
        return r9002;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019310 
(FPCore (a b c)
  :name "jeff quadratic root 2"
  :precision binary64
  (if (>= b 0.0) (/ (* 2 c) (- (- b) (sqrt (- (* b b) (* (* 4 a) c))))) (/ (+ (- b) (sqrt (- (* b b) (* (* 4 a) c)))) (* 2 a))))

Backtrace

match: no matching clause for 'binary64		L	C
match:error	/opt/racket-7.2/collects/racket/match/runtime.rkt	24	0
for-loop	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/reduce.rkt	246	3
make-multiplication-subnode	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/reduce.rkt	244	0
make-multiplication-node	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/reduce.rkt	234	0
map	/opt/racket-7.2/collects/racket/private/map.rkt	35	13
f45	/opt/racket-7.2/collects/racket/match/compiler.rkt	507	40
map	/opt/racket-7.2/collects/racket/private/map.rkt	35	13
f45	/opt/racket-7.2/collects/racket/match/compiler.rkt	507	40
simplify	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/reduce.rkt	16	0
approximate9	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/taylor.rkt	12	0
(unnamed)	/opt/racket-7.2/collects/racket/contract/private/arrow-higher-order.rkt	360	33
location-do	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/programs.rkt	64	0
loop	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/programs.rkt	73	4
loop	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/programs.rkt	73	4
location-do	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/programs.rkt	64	0
location-do	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/programs.rkt	64	0
(unnamed)	/opt/racket-7.2/collects/racket/contract/private/arrow-higher-order.rkt	360	33
for-loop	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	151	6
taylor-alt	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	145	0
for-loop	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	166	7
gen-series!	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	159	0
run-iter!	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	326	0
for-loop	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	364	4
run-improve47	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	345	0
(unnamed)	/opt/racket-7.2/collects/racket/private/more-scheme.rkt	261	28
run	/opt/racket-7.2/share/pkgs/profile-lib/main.rkt	39	2
profile-thunk16	/opt/racket-7.2/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/opt/racket-7.2/collects/racket/private/more-scheme.rkt	261	28