\[x \cdot 0.5 + y \cdot \left(\left(1 - z\right) + \log z\right)\]

x \cdot 0.5 + y \cdot \left(\left(1 - z\right) + \log z\right)

double f(double x, double y, double z) {
        double r8488 = x;
        double r8489 = 0.5;
        double r8490 = r8488 * r8489;
        double r8491 = y;
        double r8492 = 1.0;
        double r8493 = z;
        double r8494 = r8492 - r8493;
        double r8495 = log(r8493);
        double r8496 = r8494 + r8495;
        double r8497 = r8491 * r8496;
        double r8498 = r8490 + r8497;
        return r8498;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019194 
(FPCore (x y z)
  :name "System.Random.MWC.Distributions:gamma from mwc-random-0.13.3.2"

  :herbie-target
  (- (+ y (* 0.5 x)) (* y (- z (log z))))

  (+ (* x 0.5) (* y (+ (- 1.0 z) (log z)))))

Backtrace

result arity mismatch; expected number of values not received expected: 2 received: 1 in: local-binding form values...: 0		L	C
loop	/data/pavpan/nightlies/herbie/various-cleanup/src/core/extraction.rkt	25	2
(unnamed)	/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt	26	0
simplify!	/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt	220	0
run-improve47	/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt	342	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