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

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2022150 
(FPCore (x eps)
  :name "NMSE Section 6.1 mentioned, A"
  :precision binary64
  (/ (- (* (+ 1.0 (/ 1.0 eps)) (exp (- (* (- 1.0 eps) x)))) (* (- (/ 1.0 eps) 1.0) (exp (- (* (+ 1.0 eps) x))))) 2.0))

Backtrace

application: required keyword argument not supplied procedure: batch-egg-rewrite required keyword: #:rules arguments...: '(#<rule erfc-erf_binary64> #<rule erf-erfc_binary64> #<rule erf-odd_binary64> #<rule prod-diff_binary64> #<rule hypot-udef_binary64> #<rule expm1-log1p-u_binary64> #<rule log1p-expm1-u_binary64> #<rule log1p-udef_binary64> #<rule expm1-udef_binary64> #... #:depths '(1 1 1 1) #:roots '((2) (2) (2) (2))LC
(unnamed)/opt/racket-8.1/collects/racket/private/kw.rkt155814
rewrite-expressions/data/pavpan/nightlies/herbie/timeline/src/core/matcher.rkt1710
gen-rewrites!/data/pavpan/nightlies/herbie/timeline/src/patch.rkt1440
patch-table-run/data/pavpan/nightlies/herbie/timeline/src/patch.rkt2910
(unnamed)/opt/racket-8.1/collects/racket/contract/private/arrow-val-first.rkt48618
run-iter!/data/pavpan/nightlies/herbie/timeline/src/mainloop.rkt2460
mutate!/data/pavpan/nightlies/herbie/timeline/src/mainloop.rkt3790
run-improve!/data/pavpan/nightlies/herbie/timeline/src/mainloop.rkt3260
(unnamed)/data/pavpan/nightlies/herbie/timeline/src/sandbox.rkt666
(unnamed)/opt/racket-8.1/share/pkgs/profile-lib/main.rkt4010
profile-thunk/opt/racket-8.1/share/pkgs/profile-lib/main.rkt90
(unnamed)/opt/racket-8.1/collects/racket/engine.rkt4224