\[\left(\left(\sqrt{\pi \cdot 2} \cdot {\left(\left(\left(z - 1\right) + 7\right) + 0.5\right)}^{\left(\left(z - 1\right) + 0.5\right)}\right) \cdot e^{-\left(\left(\left(z - 1\right) + 7\right) + 0.5\right)}\right) \cdot \left(\left(\left(\left(\left(\left(\left(\left(0.9999999999998099298181841732002794742584 + \frac{676.5203681218850988443591631948947906494}{\left(z - 1\right) + 1}\right) + \frac{-1259.139216722402807135949842631816864014}{\left(z - 1\right) + 2}\right) + \frac{771.3234287776531346025876700878143310547}{\left(z - 1\right) + 3}\right) + \frac{-176.6150291621405870046146446838974952698}{\left(z - 1\right) + 4}\right) + \frac{12.50734327868690520801919774385169148445}{\left(z - 1\right) + 5}\right) + \frac{-0.1385710952657201178173096423051902092993}{\left(z - 1\right) + 6}\right) + \frac{9.984369578019571583242346146658263705831 \cdot 10^{-6}}{\left(z - 1\right) + 7}\right) + \frac{1.505632735149311617592788074479481785772 \cdot 10^{-7}}{\left(z - 1\right) + 8}\right)\]

\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 r8058 = atan2(1.0, 0.0);
        double r8059 = 2.0;
        double r8060 = r8058 * r8059;
        double r8061 = sqrt(r8060);
        double r8062 = z;
        double r8063 = 1.0;
        double r8064 = r8062 - r8063;
        double r8065 = 7.0;
        double r8066 = r8064 + r8065;
        double r8067 = 0.5;
        double r8068 = r8066 + r8067;
        double r8069 = r8064 + r8067;
        double r8070 = pow(r8068, r8069);
        double r8071 = r8061 * r8070;
        double r8072 = -r8068;
        double r8073 = exp(r8072);
        double r8074 = r8071 * r8073;
        double r8075 = 0.9999999999998099;
        double r8076 = 676.5203681218851;
        double r8077 = r8064 + r8063;
        double r8078 = r8076 / r8077;
        double r8079 = r8075 + r8078;
        double r8080 = -1259.1392167224028;
        double r8081 = r8064 + r8059;
        double r8082 = r8080 / r8081;
        double r8083 = r8079 + r8082;
        double r8084 = 771.3234287776531;
        double r8085 = 3.0;
        double r8086 = r8064 + r8085;
        double r8087 = r8084 / r8086;
        double r8088 = r8083 + r8087;
        double r8089 = -176.6150291621406;
        double r8090 = 4.0;
        double r8091 = r8064 + r8090;
        double r8092 = r8089 / r8091;
        double r8093 = r8088 + r8092;
        double r8094 = 12.507343278686905;
        double r8095 = 5.0;
        double r8096 = r8064 + r8095;
        double r8097 = r8094 / r8096;
        double r8098 = r8093 + r8097;
        double r8099 = -0.13857109526572012;
        double r8100 = 6.0;
        double r8101 = r8064 + r8100;
        double r8102 = r8099 / r8101;
        double r8103 = r8098 + r8102;
        double r8104 = 9.984369578019572e-06;
        double r8105 = r8104 / r8066;
        double r8106 = r8103 + r8105;
        double r8107 = 1.5056327351493116e-07;
        double r8108 = 8.0;
        double r8109 = r8064 + r8108;
        double r8110 = r8107 / r8109;
        double r8111 = r8106 + r8110;
        double r8112 = r8074 * r8111;
        return r8112;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019191 
(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

get-representation: Unknown representation #f		L	C
loop	/data/pavpan/nightlies/herbie/interface2/src/points.rkt	122	4
prepare-points	/data/pavpan/nightlies/herbie/interface2/src/points.rkt	146	0
setup-prog!34	/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt	67	0
run-improve43	/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt	339	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