\[\frac{1}{2} \cdot \log \left(\frac{1 + x}{1 - x}\right)\]

\frac{1}{2} \cdot \log \left(\frac{1 + x}{1 - x}\right)

double f(double x) {
        double r8136 = 1.0;
        double r8137 = 2.0;
        double r8138 = r8136 / r8137;
        double r8139 = x;
        double r8140 = r8136 + r8139;
        double r8141 = r8136 - r8139;
        double r8142 = r8140 / r8141;
        double r8143 = log(r8142);
        double r8144 = r8138 * r8143;
        return r8144;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019194 +o rules:numerics
(FPCore (x)
  :name "Hyperbolic arc-(co)tangent"
  (* (/ 1.0 2.0) (log (/ (+ 1.0 x) (- 1.0 x)))))

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