\[\frac{1}{2} \cdot \log \left(\frac{1 + x}{1 - x}\right) \]
(FPCore (x) :precision binary64 (* (/ 1.0 2.0) (log (/ (+ 1.0 x) (- 1.0 x)))))
double code(double x) {
	return (1.0 / 2.0) * log(((1.0 + x) / (1.0 - x)));
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = (1.0d0 / 2.0d0) * log(((1.0d0 + x) / (1.0d0 - x)))
end function
public static double code(double x) {
	return (1.0 / 2.0) * Math.log(((1.0 + x) / (1.0 - x)));
}
def code(x):
	return (1.0 / 2.0) * math.log(((1.0 + x) / (1.0 - x)))
function code(x)
	return Float64(Float64(1.0 / 2.0) * log(Float64(Float64(1.0 + x) / Float64(1.0 - x))))
end
function tmp = code(x)
	tmp = (1.0 / 2.0) * log(((1.0 + x) / (1.0 - x)));
end
code[x_] := N[(N[(1.0 / 2.0), $MachinePrecision] * N[Log[N[(N[(1.0 + x), $MachinePrecision] / N[(1.0 - x), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]
\frac{1}{2} \cdot \log \left(\frac{1 + x}{1 - x}\right)

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2022206 
(FPCore (x)
  :name "Hyperbolic arc-(co)tangent"
  :precision binary64
  (* (/ 1.0 2.0) (log (/ (+ 1.0 x) (- 1.0 x)))))

Backtrace

argmin: contract violation expected: (and/c list? (not/c empty?)) given: '() argument position: 2nd other arguments...: #<procedure:score-alt>LC
choose-alts/data/pavpan/nightlies/herbie/fix-major-atab-bug/src/mainloop.rkt950
run-iter!/data/pavpan/nightlies/herbie/fix-major-atab-bug/src/mainloop.rkt2420
mutate!/data/pavpan/nightlies/herbie/fix-major-atab-bug/src/mainloop.rkt3480
run-improve!/data/pavpan/nightlies/herbie/fix-major-atab-bug/src/mainloop.rkt2960
(unnamed)/data/pavpan/nightlies/herbie/fix-major-atab-bug/src/sandbox.rkt556
(unnamed)/usr/share/racket/pkgs/profile-lib/main.rkt4010
profile-thunk/usr/share/racket/pkgs/profile-lib/main.rkt90
(unnamed)/usr/share/racket/collects/racket/engine.rkt4224