\[\frac{\left(1 - x\right) \cdot \left(3 - x\right)}{y \cdot 3}\]
\frac{\left(1 - x\right) \cdot \left(3 - x\right)}{y \cdot 3}
double f(double x, double y) {
        double r9280 = 1.0;
        double r9281 = x;
        double r9282 = r9280 - r9281;
        double r9283 = 3.0;
        double r9284 = r9283 - r9281;
        double r9285 = r9282 * r9284;
        double r9286 = y;
        double r9287 = r9286 * r9283;
        double r9288 = r9285 / r9287;
        return r9288;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019194 
(FPCore (x y)
  :name "Diagrams.TwoD.Arc:bezierFromSweepQ1 from diagrams-lib-1.3.0.3"

  :herbie-target
  (* (/ (- 1.0 x) y) (/ (- 3.0 x) 3.0))

  (/ (* (- 1.0 x) (- 3.0 x)) (* y 3.0)))

Backtrace

result arity mismatch; expected number of values not received expected: 2 received: 1 in: local-binding form values...: 0LC
loop/data/pavpan/nightlies/herbie/various-cleanup/src/core/extraction.rkt252
(unnamed)/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt260
simplify!/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt2200
run-improve47/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt3420
(unnamed)/opt/racket-7.0/collects/racket/private/more-scheme.rkt26128
run/opt/racket-7.0/share/pkgs/profile-lib/main.rkt392
profile-thunk16/opt/racket-7.0/share/pkgs/profile-lib/main.rkt90
(unnamed)/opt/racket-7.0/collects/racket/private/more-scheme.rkt26128