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

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

double f(double x, double y, double z) {
        double r8707 = x;
        double r8708 = y;
        double r8709 = 0.5;
        double r8710 = r8708 + r8709;
        double r8711 = log(r8708);
        double r8712 = r8710 * r8711;
        double r8713 = r8707 - r8712;
        double r8714 = r8713 + r8708;
        double r8715 = z;
        double r8716 = r8714 - r8715;
        return r8716;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019179 +o rules:numerics
(FPCore (x y z)
  :name "Numeric.SpecFunctions:stirlingError from math-functions-0.1.5.2"

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

  (- (+ (- x (* (+ y 0.5) (log y))) y) 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	217	0
run-improve43	/data/pavpan/nightlies/herbie/various-cleanup/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