\[\frac{2 + \left(\left(\sqrt{2} \cdot \left(\sin x - \frac{\sin y}{16}\right)\right) \cdot \left(\sin y - \frac{\sin x}{16}\right)\right) \cdot \left(\cos x - \cos y\right)}{3 \cdot \left(\left(1 + \frac{\sqrt{5} - 1}{2} \cdot \cos x\right) + \frac{3 - \sqrt{5}}{2} \cdot \cos y\right)}\]

\frac{2 + \left(\left(\sqrt{2} \cdot \left(\sin x - \frac{\sin y}{16}\right)\right) \cdot \left(\sin y - \frac{\sin x}{16}\right)\right) \cdot \left(\cos x - \cos y\right)}{3 \cdot \left(\left(1 + \frac{\sqrt{5} - 1}{2} \cdot \cos x\right) + \frac{3 - \sqrt{5}}{2} \cdot \cos y\right)}

double f(double x, double y) {
        double r8418 = 2.0;
        double r8419 = sqrt(r8418);
        double r8420 = x;
        double r8421 = sin(r8420);
        double r8422 = y;
        double r8423 = sin(r8422);
        double r8424 = 16.0;
        double r8425 = r8423 / r8424;
        double r8426 = r8421 - r8425;
        double r8427 = r8419 * r8426;
        double r8428 = r8421 / r8424;
        double r8429 = r8423 - r8428;
        double r8430 = r8427 * r8429;
        double r8431 = cos(r8420);
        double r8432 = cos(r8422);
        double r8433 = r8431 - r8432;
        double r8434 = r8430 * r8433;
        double r8435 = r8418 + r8434;
        double r8436 = 3.0;
        double r8437 = 1.0;
        double r8438 = 5.0;
        double r8439 = sqrt(r8438);
        double r8440 = r8439 - r8437;
        double r8441 = r8440 / r8418;
        double r8442 = r8441 * r8431;
        double r8443 = r8437 + r8442;
        double r8444 = r8436 - r8439;
        double r8445 = r8444 / r8418;
        double r8446 = r8445 * r8432;
        double r8447 = r8443 + r8446;
        double r8448 = r8436 * r8447;
        double r8449 = r8435 / r8448;
        return r8449;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019194 
(FPCore (x y)
  :name "Diagrams.TwoD.Path.Metafont.Internal:hobbyF from diagrams-contrib-1.3.0.5"
  (/ (+ 2.0 (* (* (* (sqrt 2.0) (- (sin x) (/ (sin y) 16.0))) (- (sin y) (/ (sin x) 16.0))) (- (cos x) (cos y)))) (* 3.0 (+ (+ 1.0 (* (/ (- (sqrt 5.0) 1.0) 2.0) (cos x))) (* (/ (- 3.0 (sqrt 5.0)) 2.0) (cos y))))))

Backtrace

result arity mismatch; expected number of values not received expected: 2 received: 1 in: local-binding form values...: 0		L	C
loop	/data/pavpan/nightlies/herbie/various-cleanup/src/core/extraction.rkt	25	2
(unnamed)	/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt	26	0
simplify!	/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt	220	0
run-improve47	/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt	342	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