Specification

\[\begin{array}{l} \\ \frac{2}{e^{x} + e^{-x}} \end{array} \]

(FPCore (x) :precision binary64 (/ 2.0 (+ (exp x) (exp (- x)))))

double code(double x) {
	return 2.0 / (exp(x) + exp(-x));
}

real(8) function code(x)
    real(8), intent (in) :: x
    code = 2.0d0 / (exp(x) + exp(-x))
end function

public static double code(double x) {
	return 2.0 / (Math.exp(x) + Math.exp(-x));
}

def code(x):
	return 2.0 / (math.exp(x) + math.exp(-x))

function code(x)
	return Float64(2.0 / Float64(exp(x) + exp(Float64(-x))))
end

function tmp = code(x)
	tmp = 2.0 / (exp(x) + exp(-x));
end

code[x_] := N[(2.0 / N[(N[Exp[x], $MachinePrecision] + N[Exp[(-x)], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]

\begin{array}{l}

\\
\frac{2}{e^{x} + e^{-x}}
\end{array}

Reproduce

herbie shell --seed 2023271 
(FPCore (x)
  :name "Hyperbolic secant"
  :precision binary64
  (/ 2.0 (+ (exp x) (exp (- 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