\[\frac{\pi}{\sin \left(\pi \cdot z\right)} \cdot \left(\left(\left(\sqrt{\pi \cdot 2} \cdot {\left(\left(\left(\left(1 - z\right) - 1\right) + 7\right) + 0.5\right)}^{\left(\left(\left(1 - z\right) - 1\right) + 0.5\right)}\right) \cdot e^{-\left(\left(\left(\left(1 - z\right) - 1\right) + 7\right) + 0.5\right)}\right) \cdot \left(\left(\left(\left(\left(\left(\left(\left(0.9999999999998099298181841732002794742584 + \frac{676.5203681218850988443591631948947906494}{\left(\left(1 - z\right) - 1\right) + 1}\right) + \frac{-1259.139216722402807135949842631816864014}{\left(\left(1 - z\right) - 1\right) + 2}\right) + \frac{771.3234287776531346025876700878143310547}{\left(\left(1 - z\right) - 1\right) + 3}\right) + \frac{-176.6150291621405870046146446838974952698}{\left(\left(1 - z\right) - 1\right) + 4}\right) + \frac{12.50734327868690520801919774385169148445}{\left(\left(1 - z\right) - 1\right) + 5}\right) + \frac{-0.1385710952657201178173096423051902092993}{\left(\left(1 - z\right) - 1\right) + 6}\right) + \frac{9.984369578019571583242346146658263705831 \cdot 10^{-6}}{\left(\left(1 - z\right) - 1\right) + 7}\right) + \frac{1.505632735149311617592788074479481785772 \cdot 10^{-7}}{\left(\left(1 - z\right) - 1\right) + 8}\right)\right)\]
\frac{\pi}{\sin \left(\pi \cdot z\right)} \cdot \left(\left(\left(\sqrt{\pi \cdot 2} \cdot {\left(\left(\left(\left(1 - z\right) - 1\right) + 7\right) + 0.5\right)}^{\left(\left(\left(1 - z\right) - 1\right) + 0.5\right)}\right) \cdot e^{-\left(\left(\left(\left(1 - z\right) - 1\right) + 7\right) + 0.5\right)}\right) \cdot \left(\left(\left(\left(\left(\left(\left(\left(0.9999999999998099298181841732002794742584 + \frac{676.5203681218850988443591631948947906494}{\left(\left(1 - z\right) - 1\right) + 1}\right) + \frac{-1259.139216722402807135949842631816864014}{\left(\left(1 - z\right) - 1\right) + 2}\right) + \frac{771.3234287776531346025876700878143310547}{\left(\left(1 - z\right) - 1\right) + 3}\right) + \frac{-176.6150291621405870046146446838974952698}{\left(\left(1 - z\right) - 1\right) + 4}\right) + \frac{12.50734327868690520801919774385169148445}{\left(\left(1 - z\right) - 1\right) + 5}\right) + \frac{-0.1385710952657201178173096423051902092993}{\left(\left(1 - z\right) - 1\right) + 6}\right) + \frac{9.984369578019571583242346146658263705831 \cdot 10^{-6}}{\left(\left(1 - z\right) - 1\right) + 7}\right) + \frac{1.505632735149311617592788074479481785772 \cdot 10^{-7}}{\left(\left(1 - z\right) - 1\right) + 8}\right)\right)
double f(double z) {
        double r57022 = atan2(1.0, 0.0);
        double r57023 = z;
        double r57024 = r57022 * r57023;
        double r57025 = sin(r57024);
        double r57026 = r57022 / r57025;
        double r57027 = 2.0;
        double r57028 = r57022 * r57027;
        double r57029 = sqrt(r57028);
        double r57030 = 1.0;
        double r57031 = r57030 - r57023;
        double r57032 = r57031 - r57030;
        double r57033 = 7.0;
        double r57034 = r57032 + r57033;
        double r57035 = 0.5;
        double r57036 = r57034 + r57035;
        double r57037 = r57032 + r57035;
        double r57038 = pow(r57036, r57037);
        double r57039 = r57029 * r57038;
        double r57040 = -r57036;
        double r57041 = exp(r57040);
        double r57042 = r57039 * r57041;
        double r57043 = 0.9999999999998099;
        double r57044 = 676.5203681218851;
        double r57045 = r57032 + r57030;
        double r57046 = r57044 / r57045;
        double r57047 = r57043 + r57046;
        double r57048 = -1259.1392167224028;
        double r57049 = r57032 + r57027;
        double r57050 = r57048 / r57049;
        double r57051 = r57047 + r57050;
        double r57052 = 771.3234287776531;
        double r57053 = 3.0;
        double r57054 = r57032 + r57053;
        double r57055 = r57052 / r57054;
        double r57056 = r57051 + r57055;
        double r57057 = -176.6150291621406;
        double r57058 = 4.0;
        double r57059 = r57032 + r57058;
        double r57060 = r57057 / r57059;
        double r57061 = r57056 + r57060;
        double r57062 = 12.507343278686905;
        double r57063 = 5.0;
        double r57064 = r57032 + r57063;
        double r57065 = r57062 / r57064;
        double r57066 = r57061 + r57065;
        double r57067 = -0.13857109526572012;
        double r57068 = 6.0;
        double r57069 = r57032 + r57068;
        double r57070 = r57067 / r57069;
        double r57071 = r57066 + r57070;
        double r57072 = 9.984369578019572e-06;
        double r57073 = r57072 / r57034;
        double r57074 = r57071 + r57073;
        double r57075 = 1.5056327351493116e-07;
        double r57076 = 8.0;
        double r57077 = r57032 + r57076;
        double r57078 = r57075 / r57077;
        double r57079 = r57074 + r57078;
        double r57080 = r57042 * r57079;
        double r57081 = r57026 * r57080;
        return r57081;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019196 
(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

get-representation: Unknown representation #fLC
(unnamed)/data/pavpan/nightlies/herbie/master/src/core/localize.rkt2313
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
map/opt/racket-7.0/collects/racket/private/map.rkt3513
parse-loop30/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
parse-loop30/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
parse-loop30/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
parse-loop30/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/master/src/core/localize.rkt610
localize!/data/pavpan/nightlies/herbie/master/src/mainloop.rkt1230
run-iter!/data/pavpan/nightlies/herbie/master/src/mainloop.rkt3230
for-loop/data/pavpan/nightlies/herbie/master/src/mainloop.rkt3594
run-improve47/data/pavpan/nightlies/herbie/master/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