\[\frac{\pi}{\sin \left(\pi \cdot z\right)} \cdot \left(\left(\left(\sqrt{\pi \cdot 2.0} \cdot {\left(\left(\left(\left(1.0 - z\right) - 1.0\right) + 7.0\right) + 0.5\right)}^{\left(\left(\left(1.0 - z\right) - 1.0\right) + 0.5\right)}\right) \cdot e^{-\left(\left(\left(\left(1.0 - z\right) - 1.0\right) + 7.0\right) + 0.5\right)}\right) \cdot \left(\left(\left(\left(\left(\left(\left(\left(0.9999999999998099 + \frac{676.5203681218851}{\left(\left(1.0 - z\right) - 1.0\right) + 1.0}\right) + \frac{-1259.1392167224028}{\left(\left(1.0 - z\right) - 1.0\right) + 2.0}\right) + \frac{771.3234287776531}{\left(\left(1.0 - z\right) - 1.0\right) + 3.0}\right) + \frac{-176.6150291621406}{\left(\left(1.0 - z\right) - 1.0\right) + 4.0}\right) + \frac{12.507343278686905}{\left(\left(1.0 - z\right) - 1.0\right) + 5.0}\right) + \frac{-0.13857109526572012}{\left(\left(1.0 - z\right) - 1.0\right) + 6.0}\right) + \frac{9.984369578019572 \cdot 10^{-06}}{\left(\left(1.0 - z\right) - 1.0\right) + 7.0}\right) + \frac{1.5056327351493116 \cdot 10^{-07}}{\left(\left(1.0 - z\right) - 1.0\right) + 8.0}\right)\right)\]
\frac{\pi}{\sin \left(\pi \cdot z\right)} \cdot \left(\left(\left(\sqrt{\pi \cdot 2.0} \cdot {\left(\left(\left(\left(1.0 - z\right) - 1.0\right) + 7.0\right) + 0.5\right)}^{\left(\left(\left(1.0 - z\right) - 1.0\right) + 0.5\right)}\right) \cdot e^{-\left(\left(\left(\left(1.0 - z\right) - 1.0\right) + 7.0\right) + 0.5\right)}\right) \cdot \left(\left(\left(\left(\left(\left(\left(\left(0.9999999999998099 + \frac{676.5203681218851}{\left(\left(1.0 - z\right) - 1.0\right) + 1.0}\right) + \frac{-1259.1392167224028}{\left(\left(1.0 - z\right) - 1.0\right) + 2.0}\right) + \frac{771.3234287776531}{\left(\left(1.0 - z\right) - 1.0\right) + 3.0}\right) + \frac{-176.6150291621406}{\left(\left(1.0 - z\right) - 1.0\right) + 4.0}\right) + \frac{12.507343278686905}{\left(\left(1.0 - z\right) - 1.0\right) + 5.0}\right) + \frac{-0.13857109526572012}{\left(\left(1.0 - z\right) - 1.0\right) + 6.0}\right) + \frac{9.984369578019572 \cdot 10^{-06}}{\left(\left(1.0 - z\right) - 1.0\right) + 7.0}\right) + \frac{1.5056327351493116 \cdot 10^{-07}}{\left(\left(1.0 - z\right) - 1.0\right) + 8.0}\right)\right)
double f(double z) {
        double r3907597 = atan2(1.0, 0.0);
        double r3907598 = z;
        double r3907599 = r3907597 * r3907598;
        double r3907600 = sin(r3907599);
        double r3907601 = r3907597 / r3907600;
        double r3907602 = 2.0;
        double r3907603 = r3907597 * r3907602;
        double r3907604 = sqrt(r3907603);
        double r3907605 = 1.0;
        double r3907606 = r3907605 - r3907598;
        double r3907607 = r3907606 - r3907605;
        double r3907608 = 7.0;
        double r3907609 = r3907607 + r3907608;
        double r3907610 = 0.5;
        double r3907611 = r3907609 + r3907610;
        double r3907612 = r3907607 + r3907610;
        double r3907613 = pow(r3907611, r3907612);
        double r3907614 = r3907604 * r3907613;
        double r3907615 = -r3907611;
        double r3907616 = exp(r3907615);
        double r3907617 = r3907614 * r3907616;
        double r3907618 = 0.9999999999998099;
        double r3907619 = 676.5203681218851;
        double r3907620 = r3907607 + r3907605;
        double r3907621 = r3907619 / r3907620;
        double r3907622 = r3907618 + r3907621;
        double r3907623 = -1259.1392167224028;
        double r3907624 = r3907607 + r3907602;
        double r3907625 = r3907623 / r3907624;
        double r3907626 = r3907622 + r3907625;
        double r3907627 = 771.3234287776531;
        double r3907628 = 3.0;
        double r3907629 = r3907607 + r3907628;
        double r3907630 = r3907627 / r3907629;
        double r3907631 = r3907626 + r3907630;
        double r3907632 = -176.6150291621406;
        double r3907633 = 4.0;
        double r3907634 = r3907607 + r3907633;
        double r3907635 = r3907632 / r3907634;
        double r3907636 = r3907631 + r3907635;
        double r3907637 = 12.507343278686905;
        double r3907638 = 5.0;
        double r3907639 = r3907607 + r3907638;
        double r3907640 = r3907637 / r3907639;
        double r3907641 = r3907636 + r3907640;
        double r3907642 = -0.13857109526572012;
        double r3907643 = 6.0;
        double r3907644 = r3907607 + r3907643;
        double r3907645 = r3907642 / r3907644;
        double r3907646 = r3907641 + r3907645;
        double r3907647 = 9.984369578019572e-06;
        double r3907648 = r3907647 / r3907609;
        double r3907649 = r3907646 + r3907648;
        double r3907650 = 1.5056327351493116e-07;
        double r3907651 = 8.0;
        double r3907652 = r3907607 + r3907651;
        double r3907653 = r3907650 / r3907652;
        double r3907654 = r3907649 + r3907653;
        double r3907655 = r3907617 * r3907654;
        double r3907656 = r3907601 * r3907655;
        return r3907656;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019165 +o rules:numerics
(FPCore (z)
  :name "Jmat.Real.gamma, branch z less than 0.5"
  (* (/ PI (sin (* PI z))) (* (* (* (sqrt (* PI 2.0)) (pow (+ (+ (- (- 1.0 z) 1.0) 7.0) 0.5) (+ (- (- 1.0 z) 1.0) 0.5))) (exp (- (+ (+ (- (- 1.0 z) 1.0) 7.0) 0.5)))) (+ (+ (+ (+ (+ (+ (+ (+ 0.9999999999998099 (/ 676.5203681218851 (+ (- (- 1.0 z) 1.0) 1.0))) (/ -1259.1392167224028 (+ (- (- 1.0 z) 1.0) 2.0))) (/ 771.3234287776531 (+ (- (- 1.0 z) 1.0) 3.0))) (/ -176.6150291621406 (+ (- (- 1.0 z) 1.0) 4.0))) (/ 12.507343278686905 (+ (- (- 1.0 z) 1.0) 5.0))) (/ -0.13857109526572012 (+ (- (- 1.0 z) 1.0) 6.0))) (/ 9.984369578019572e-06 (+ (- (- 1.0 z) 1.0) 7.0))) (/ 1.5056327351493116e-07 (+ (- (- 1.0 z) 1.0) 8.0))))))

Backtrace

->bf: contract violation expected: value? given: 'PI in: the 1st argument of (-> value? bigvalue?) contract from: (function ->bf) blaming: /data/pavpan/nightlies/herbie/optional-posits/src/float.rkt (assuming the contract is correct) at: /data/pavpan/nightlies/herbie/optional-posits/src/float.rkt:163.18LC
raise-blame-error16/opt/racket-7.0/collects/racket/contract/private/blame.rkt3470
(unnamed)/opt/racket-7.0/collects/racket/contract/private/arrow-higher-order.rkt35733
(unnamed)/data/pavpan/nightlies/herbie/optional-posits/src/core/localize.rkt2213
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
loop/opt/racket-7.0/collects/racket/private/map.rkt4019
parse-loop15/opt/racket-7.0/collects/racket/match/compiler.rkt41815
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
map/opt/racket-7.0/collects/racket/private/map.rkt3513
f9/opt/racket-7.0/collects/racket/match/compiler.rkt50740
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
loop/opt/racket-7.0/collects/racket/private/map.rkt4019
parse-loop15/opt/racket-7.0/collects/racket/match/compiler.rkt41815
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
localize-error/data/pavpan/nightlies/herbie/optional-posits/src/core/localize.rkt520
localize!/data/pavpan/nightlies/herbie/optional-posits/src/mainloop.rkt1160
run-iter!/data/pavpan/nightlies/herbie/optional-posits/src/mainloop.rkt3170
for-loop/data/pavpan/nightlies/herbie/optional-posits/src/mainloop.rkt3514
run-improve40/data/pavpan/nightlies/herbie/optional-posits/src/mainloop.rkt3360
(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