\[\frac{\pi}{\sin \left(\pi \cdot z\right)} \cdot \left(\left(\left(\sqrt{\pi \cdot 2} \cdot {\left(\left(\left(\left(1 - z\right) - 1\right) + 7\right) + 0.5\right)}^{\left(\left(\left(1 - z\right) - 1\right) + 0.5\right)}\right) \cdot e^{-\left(\left(\left(\left(1 - z\right) - 1\right) + 7\right) + 0.5\right)}\right) \cdot \left(\left(\left(\left(\left(\left(\left(\left(0.9999999999998099298181841732002794742584 + \frac{676.5203681218850988443591631948947906494}{\left(\left(1 - z\right) - 1\right) + 1}\right) + \frac{-1259.139216722402807135949842631816864014}{\left(\left(1 - z\right) - 1\right) + 2}\right) + \frac{771.3234287776531346025876700878143310547}{\left(\left(1 - z\right) - 1\right) + 3}\right) + \frac{-176.6150291621405870046146446838974952698}{\left(\left(1 - z\right) - 1\right) + 4}\right) + \frac{12.50734327868690520801919774385169148445}{\left(\left(1 - z\right) - 1\right) + 5}\right) + \frac{-0.1385710952657201178173096423051902092993}{\left(\left(1 - z\right) - 1\right) + 6}\right) + \frac{9.984369578019571583242346146658263705831 \cdot 10^{-6}}{\left(\left(1 - z\right) - 1\right) + 7}\right) + \frac{1.505632735149311617592788074479481785772 \cdot 10^{-7}}{\left(\left(1 - z\right) - 1\right) + 8}\right)\right)\]
\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 r8557 = atan2(1.0, 0.0);
        double r8558 = z;
        double r8559 = r8557 * r8558;
        double r8560 = sin(r8559);
        double r8561 = r8557 / r8560;
        double r8562 = 2.0;
        double r8563 = r8557 * r8562;
        double r8564 = sqrt(r8563);
        double r8565 = 1.0;
        double r8566 = r8565 - r8558;
        double r8567 = r8566 - r8565;
        double r8568 = 7.0;
        double r8569 = r8567 + r8568;
        double r8570 = 0.5;
        double r8571 = r8569 + r8570;
        double r8572 = r8567 + r8570;
        double r8573 = pow(r8571, r8572);
        double r8574 = r8564 * r8573;
        double r8575 = -r8571;
        double r8576 = exp(r8575);
        double r8577 = r8574 * r8576;
        double r8578 = 0.9999999999998099;
        double r8579 = 676.5203681218851;
        double r8580 = r8567 + r8565;
        double r8581 = r8579 / r8580;
        double r8582 = r8578 + r8581;
        double r8583 = -1259.1392167224028;
        double r8584 = r8567 + r8562;
        double r8585 = r8583 / r8584;
        double r8586 = r8582 + r8585;
        double r8587 = 771.3234287776531;
        double r8588 = 3.0;
        double r8589 = r8567 + r8588;
        double r8590 = r8587 / r8589;
        double r8591 = r8586 + r8590;
        double r8592 = -176.6150291621406;
        double r8593 = 4.0;
        double r8594 = r8567 + r8593;
        double r8595 = r8592 / r8594;
        double r8596 = r8591 + r8595;
        double r8597 = 12.507343278686905;
        double r8598 = 5.0;
        double r8599 = r8567 + r8598;
        double r8600 = r8597 / r8599;
        double r8601 = r8596 + r8600;
        double r8602 = -0.13857109526572012;
        double r8603 = 6.0;
        double r8604 = r8567 + r8603;
        double r8605 = r8602 / r8604;
        double r8606 = r8601 + r8605;
        double r8607 = 9.984369578019572e-06;
        double r8608 = r8607 / r8569;
        double r8609 = r8606 + r8608;
        double r8610 = 1.5056327351493116e-07;
        double r8611 = 8.0;
        double r8612 = r8567 + r8611;
        double r8613 = r8610 / r8612;
        double r8614 = r8609 + r8613;
        double r8615 = r8577 * r8614;
        double r8616 = r8561 * r8615;
        return r8616;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019191 
(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
loop/data/pavpan/nightlies/herbie/interface2/src/points.rkt1224
prepare-points/data/pavpan/nightlies/herbie/interface2/src/points.rkt1460
setup-prog!34/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt670
run-improve43/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt3390
(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