\[\left(\left(\sqrt{\pi \cdot 2} \cdot {\left(\left(\left(z - 1\right) + 7\right) + 0.5\right)}^{\left(\left(z - 1\right) + 0.5\right)}\right) \cdot e^{-\left(\left(\left(z - 1\right) + 7\right) + 0.5\right)}\right) \cdot \left(\left(\left(\left(\left(\left(\left(\left(0.9999999999998099298181841732002794742584 + \frac{676.5203681218850988443591631948947906494}{\left(z - 1\right) + 1}\right) + \frac{-1259.139216722402807135949842631816864014}{\left(z - 1\right) + 2}\right) + \frac{771.3234287776531346025876700878143310547}{\left(z - 1\right) + 3}\right) + \frac{-176.6150291621405870046146446838974952698}{\left(z - 1\right) + 4}\right) + \frac{12.50734327868690520801919774385169148445}{\left(z - 1\right) + 5}\right) + \frac{-0.1385710952657201178173096423051902092993}{\left(z - 1\right) + 6}\right) + \frac{9.984369578019571583242346146658263705831 \cdot 10^{-6}}{\left(z - 1\right) + 7}\right) + \frac{1.505632735149311617592788074479481785772 \cdot 10^{-7}}{\left(z - 1\right) + 8}\right)\]
\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(0.9999999999998099298181841732002794742584 + \frac{676.5203681218850988443591631948947906494}{\left(z - 1\right) + 1}\right) + \frac{-1259.139216722402807135949842631816864014}{\left(z - 1\right) + 2}\right) + \frac{771.3234287776531346025876700878143310547}{\left(z - 1\right) + 3}\right) + \frac{-176.6150291621405870046146446838974952698}{\left(z - 1\right) + 4}\right) + \frac{12.50734327868690520801919774385169148445}{\left(z - 1\right) + 5}\right) + \frac{-0.1385710952657201178173096423051902092993}{\left(z - 1\right) + 6}\right) + \frac{9.984369578019571583242346146658263705831 \cdot 10^{-6}}{\left(z - 1\right) + 7}\right) + \frac{1.505632735149311617592788074479481785772 \cdot 10^{-7}}{\left(z - 1\right) + 8}\right)
double f(double z) {
        double r8851 = atan2(1.0, 0.0);
        double r8852 = 2.0;
        double r8853 = r8851 * r8852;
        double r8854 = sqrt(r8853);
        double r8855 = z;
        double r8856 = 1.0;
        double r8857 = r8855 - r8856;
        double r8858 = 7.0;
        double r8859 = r8857 + r8858;
        double r8860 = 0.5;
        double r8861 = r8859 + r8860;
        double r8862 = r8857 + r8860;
        double r8863 = pow(r8861, r8862);
        double r8864 = r8854 * r8863;
        double r8865 = -r8861;
        double r8866 = exp(r8865);
        double r8867 = r8864 * r8866;
        double r8868 = 0.9999999999998099;
        double r8869 = 676.5203681218851;
        double r8870 = r8857 + r8856;
        double r8871 = r8869 / r8870;
        double r8872 = r8868 + r8871;
        double r8873 = -1259.1392167224028;
        double r8874 = r8857 + r8852;
        double r8875 = r8873 / r8874;
        double r8876 = r8872 + r8875;
        double r8877 = 771.3234287776531;
        double r8878 = 3.0;
        double r8879 = r8857 + r8878;
        double r8880 = r8877 / r8879;
        double r8881 = r8876 + r8880;
        double r8882 = -176.6150291621406;
        double r8883 = 4.0;
        double r8884 = r8857 + r8883;
        double r8885 = r8882 / r8884;
        double r8886 = r8881 + r8885;
        double r8887 = 12.507343278686905;
        double r8888 = 5.0;
        double r8889 = r8857 + r8888;
        double r8890 = r8887 / r8889;
        double r8891 = r8886 + r8890;
        double r8892 = -0.13857109526572012;
        double r8893 = 6.0;
        double r8894 = r8857 + r8893;
        double r8895 = r8892 / r8894;
        double r8896 = r8891 + r8895;
        double r8897 = 9.984369578019572e-06;
        double r8898 = r8897 / r8859;
        double r8899 = r8896 + r8898;
        double r8900 = 1.5056327351493116e-07;
        double r8901 = 8.0;
        double r8902 = r8857 + r8901;
        double r8903 = r8900 / r8902;
        double r8904 = r8899 + r8903;
        double r8905 = r8867 * r8904;
        return r8905;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019173 +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

atab-pick-alt: contract violation expected: alt? given: '(#<alt (λ (z) (* (* (sqrt (* PI 2.0)) (/ (pow (- (+ 7.0 (+ z 0.5)) 1.0) (+ (- z 1.0) 0.5)) (exp (- z (- (- 1.0 0.5) 7.0))))) (+ (/ -1259.1392167224028 (+ 2.0 (- z 1.0))) (+ (+ (+ (+ 0.9999999999998099 (/ 676.5203681218851 z)) (/ -176.6150291621406 (+ ... in: the range of the #:picking-func argument of (-> alt-table? #:only-fresh boolean? #:picking-func (-> (listof alt?) alt?) (values alt? alt-table?)) contract from: /data/pavpan/nightlies/herbie/no-costs-2/src/core/alt-table.rkt blaming: /data/pavpan/nightlies/herbie/no-costs-2/src/mainloop.rkt (assuming the contract is correct) at: /data/pavpan/nightlies/herbie/no-costs-2/src/core/alt-table.rkt:13.3LC
raise-blame-error16/opt/racket-7.0/collects/racket/contract/private/blame.rkt3470
(unnamed)/data/pavpan/nightlies/herbie/no-costs-2/src/core/alt-table.rkt590
(unnamed)/opt/racket-7.0/collects/racket/contract/private/arrow-val-first.rkt38818
choose-best-alt!/data/pavpan/nightlies/herbie/no-costs-2/src/mainloop.rkt1100
run-iter!/data/pavpan/nightlies/herbie/no-costs-2/src/mainloop.rkt3190
for-loop/data/pavpan/nightlies/herbie/no-costs-2/src/mainloop.rkt3534
run-improve43/data/pavpan/nightlies/herbie/no-costs-2/src/mainloop.rkt3380
(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