\[\left(\left(\sqrt{\pi \cdot 2} \cdot {\left(\left(\left(z - 1\right) + 7\right) + 0.5\right)}^{\left(\left(z - 1\right) + 0.5\right)}\right) \cdot e^{-\left(\left(\left(z - 1\right) + 7\right) + 0.5\right)}\right) \cdot \left(\left(\left(\left(\left(\left(\left(\left(0.99999999999980993 + \frac{676.520368121885099}{\left(z - 1\right) + 1}\right) + \frac{-1259.13921672240281}{\left(z - 1\right) + 2}\right) + \frac{771.32342877765313}{\left(z - 1\right) + 3}\right) + \frac{-176.615029162140587}{\left(z - 1\right) + 4}\right) + \frac{12.5073432786869052}{\left(z - 1\right) + 5}\right) + \frac{-0.138571095265720118}{\left(z - 1\right) + 6}\right) + \frac{9.98436957801957158 \cdot 10^{-6}}{\left(z - 1\right) + 7}\right) + \frac{1.50563273514931162 \cdot 10^{-7}}{\left(z - 1\right) + 8}\right)\]
\left(\left(\sqrt{\pi \cdot 2} \cdot {\left(\left(\left(z - 1\right) + 7\right) + 0.5\right)}^{\left(\left(z - 1\right) + 0.5\right)}\right) \cdot e^{-\left(\left(\left(z - 1\right) + 7\right) + 0.5\right)}\right) \cdot \left(\left(\left(\left(\left(\left(\left(\left(0.99999999999980993 + \frac{676.520368121885099}{\left(z - 1\right) + 1}\right) + \frac{-1259.13921672240281}{\left(z - 1\right) + 2}\right) + \frac{771.32342877765313}{\left(z - 1\right) + 3}\right) + \frac{-176.615029162140587}{\left(z - 1\right) + 4}\right) + \frac{12.5073432786869052}{\left(z - 1\right) + 5}\right) + \frac{-0.138571095265720118}{\left(z - 1\right) + 6}\right) + \frac{9.98436957801957158 \cdot 10^{-6}}{\left(z - 1\right) + 7}\right) + \frac{1.50563273514931162 \cdot 10^{-7}}{\left(z - 1\right) + 8}\right)
double f(double z) {
        double r8429 = atan2(1.0, 0.0);
        double r8430 = 2.0;
        double r8431 = r8429 * r8430;
        double r8432 = sqrt(r8431);
        double r8433 = z;
        double r8434 = 1.0;
        double r8435 = r8433 - r8434;
        double r8436 = 7.0;
        double r8437 = r8435 + r8436;
        double r8438 = 0.5;
        double r8439 = r8437 + r8438;
        double r8440 = r8435 + r8438;
        double r8441 = pow(r8439, r8440);
        double r8442 = r8432 * r8441;
        double r8443 = -r8439;
        double r8444 = exp(r8443);
        double r8445 = r8442 * r8444;
        double r8446 = 0.9999999999998099;
        double r8447 = 676.5203681218851;
        double r8448 = r8435 + r8434;
        double r8449 = r8447 / r8448;
        double r8450 = r8446 + r8449;
        double r8451 = -1259.1392167224028;
        double r8452 = r8435 + r8430;
        double r8453 = r8451 / r8452;
        double r8454 = r8450 + r8453;
        double r8455 = 771.3234287776531;
        double r8456 = 3.0;
        double r8457 = r8435 + r8456;
        double r8458 = r8455 / r8457;
        double r8459 = r8454 + r8458;
        double r8460 = -176.6150291621406;
        double r8461 = 4.0;
        double r8462 = r8435 + r8461;
        double r8463 = r8460 / r8462;
        double r8464 = r8459 + r8463;
        double r8465 = 12.507343278686905;
        double r8466 = 5.0;
        double r8467 = r8435 + r8466;
        double r8468 = r8465 / r8467;
        double r8469 = r8464 + r8468;
        double r8470 = -0.13857109526572012;
        double r8471 = 6.0;
        double r8472 = r8435 + r8471;
        double r8473 = r8470 / r8472;
        double r8474 = r8469 + r8473;
        double r8475 = 9.984369578019572e-06;
        double r8476 = r8475 / r8437;
        double r8477 = r8474 + r8476;
        double r8478 = 1.5056327351493116e-07;
        double r8479 = 8.0;
        double r8480 = r8435 + r8479;
        double r8481 = r8478 / r8480;
        double r8482 = r8477 + r8481;
        double r8483 = r8445 * r8482;
        return r8483;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019194 +o rules:numerics
(FPCore (z)
  :name "Jmat.Real.gamma, branch z greater than 0.5"
  (* (* (* (sqrt (* PI 2.0)) (pow (+ (+ (- z 1.0) 7.0) 0.5) (+ (- z 1.0) 0.5))) (exp (- (+ (+ (- z 1.0) 7.0) 0.5)))) (+ (+ (+ (+ (+ (+ (+ (+ 0.9999999999998099 (/ 676.5203681218851 (+ (- z 1.0) 1.0))) (/ -1259.1392167224028 (+ (- z 1.0) 2.0))) (/ 771.3234287776531 (+ (- z 1.0) 3.0))) (/ -176.6150291621406 (+ (- z 1.0) 4.0))) (/ 12.507343278686905 (+ (- z 1.0) 5.0))) (/ -0.13857109526572012 (+ (- z 1.0) 6.0))) (/ 9.984369578019572e-06 (+ (- z 1.0) 7.0))) (/ 1.5056327351493116e-07 (+ (- z 1.0) 8.0)))))

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