Hyperbolic tangent

Specification

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\[\begin{array}{l} \\ \begin{array}{l} t_0 := e^{-x}\\ \frac{e^{x} - t\_0}{e^{x} + t\_0} \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (let* ((t_0 (exp (- x)))) (/ (- (exp x) t_0) (+ (exp x) t_0))))
double code(double x) {
	double t_0 = exp(-x);
	return (exp(x) - t_0) / (exp(x) + t_0);
}

real(8) function code(x)
    real(8), intent (in) :: x
    real(8) :: t_0
    t_0 = exp(-x)
    code = (exp(x) - t_0) / (exp(x) + t_0)
end function

public static double code(double x) {
	double t_0 = Math.exp(-x);
	return (Math.exp(x) - t_0) / (Math.exp(x) + t_0);
}

def code(x):
	t_0 = math.exp(-x)
	return (math.exp(x) - t_0) / (math.exp(x) + t_0)

function code(x)
	t_0 = exp(Float64(-x))
	return Float64(Float64(exp(x) - t_0) / Float64(exp(x) + t_0))
end

function tmp = code(x)
	t_0 = exp(-x);
	tmp = (exp(x) - t_0) / (exp(x) + t_0);
end

code[x_] := Block[{t$95$0 = N[Exp[(-x)], $MachinePrecision]}, N[(N[(N[Exp[x], $MachinePrecision] - t$95$0), $MachinePrecision] / N[(N[Exp[x], $MachinePrecision] + t$95$0), $MachinePrecision]), $MachinePrecision]]

\begin{array}{l}

\\
\begin{array}{l}
t_0 := e^{-x}\\
\frac{e^{x} - t\_0}{e^{x} + t\_0}
\end{array}
\end{array}

Reproduce

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herbie shell --seed 2024196 
(FPCore (x)
  :name "Hyperbolic tangent"
  :precision binary64
  (/ (- (exp x) (exp (- x))) (+ (exp x) (exp (- x)))))

Please file a bug report with this information.

Backtrace

vector-set!: contract violation expected: exact-nonnegative-integer? given: -1 argument position: 2nd first argument...: '#(#f #t #f #f #f #f #f #f)LC
backward-pass/home/nightlies/rival/main/eval/adjust.rkt80
rival-machine-adjust/home/nightlies/rival/main/eval/run.rkt980
rival-machine-full/home/nightlies/rival/main/eval/main.rkt160
rival-apply/home/nightlies/rival/main/eval/main.rkt560
(unnamed)/usr/local/racket/collects/racket/contract/private/arrow-val-first.rkt48618
(unnamed)/home/nightlies/herbie/main/src/sampling.rkt1594
ival-eval/home/nightlies/herbie/main/src/sampling.rkt1530
<eval-prog-real>/home/nightlies/herbie/main/src/sampling.rkt1882
predict-errors/home/nightlies/herbie/main/src/explain.rkt860
explain/home/nightlies/herbie/main/src/explain.rkt7360
explain!/home/nightlies/herbie/main/src/mainloop.rkt3390
mutate!/home/nightlies/herbie/main/src/mainloop.rkt620
run-improve!/home/nightlies/herbie/main/src/mainloop.rkt480
get-alternatives/report/home/nightlies/herbie/main/src/sandbox.rkt1670
(unnamed)/home/nightlies/herbie/main/src/sandbox.rkt2616
(unnamed)/usr/local/racket/share/pkgs/profile-lib/main.rkt4010
profile-thunk/usr/local/racket/share/pkgs/profile-lib/main.rkt90
(unnamed)/usr/local/racket/collects/racket/engine.rkt4224