Specification

\[\begin{array}{l} \\ \log x - \log \log x \end{array} \]

(FPCore (x) :precision binary64 (- (log x) (log (log x))))

double code(double x) {
	return log(x) - log(log(x));
}

real(8) function code(x)
    real(8), intent (in) :: x
    code = log(x) - log(log(x))
end function

public static double code(double x) {
	return Math.log(x) - Math.log(Math.log(x));
}

def code(x):
	return math.log(x) - math.log(math.log(x))

function code(x)
	return Float64(log(x) - log(log(x)))
end

function tmp = code(x)
	tmp = log(x) - log(log(x));
end

code[x_] := N[(N[Log[x], $MachinePrecision] - N[Log[N[Log[x], $MachinePrecision]], $MachinePrecision]), $MachinePrecision]

\begin{array}{l}

\\
\log x - \log \log x
\end{array}

Reproduce

herbie shell --seed 2023271 
(FPCore (x)
  :name "Jmat.Real.lambertw, estimator"
  :precision binary64
  (- (log x) (log (log x))))

Please file a bug report with this information.

length: contract violation expected: list? given: 8000		L	C
(unnamed)	/home/nightlies/herbie/arb-support/egg-herbie/main.rkt	111	2
egraph-run	/home/nightlies/herbie/main/src/core/egg-herbie.rkt	502	0
egraph-run-rules	/home/nightlies/herbie/main/src/core/egg-herbie.rkt	559	0
run-egg	/home/nightlies/herbie/main/src/core/egg-herbie.rkt	288	0
simplify-batch	/home/nightlies/herbie/main/src/core/simplify.rkt	15	0
(unnamed)	/usr/share/racket/collects/racket/contract/private/arrow-higher-order.rkt	379	33
find-preprocessing	/home/nightlies/herbie/main/src/preprocess.rkt	11	0
run-improve!	/home/nightlies/herbie/main/src/mainloop.rkt	325	0
get-alternatives/report	/home/nightlies/herbie/main/src/sandbox.rkt	149	0
(unnamed)	/home/nightlies/herbie/main/src/sandbox.rkt	245	6
(unnamed)	/usr/share/racket/pkgs/profile-lib/main.rkt	40	10
profile-thunk	/usr/share/racket/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/usr/share/racket/collects/racket/engine.rkt	42	24