Specification

\[\begin{array}{l} \\ \frac{1}{x + 1} - \frac{1}{x - 1} \end{array} \]

(FPCore (x) :precision binary64 (- (/ 1.0 (+ x 1.0)) (/ 1.0 (- x 1.0))))

double code(double x) {
	return (1.0 / (x + 1.0)) - (1.0 / (x - 1.0));
}

real(8) function code(x)
    real(8), intent (in) :: x
    code = (1.0d0 / (x + 1.0d0)) - (1.0d0 / (x - 1.0d0))
end function

public static double code(double x) {
	return (1.0 / (x + 1.0)) - (1.0 / (x - 1.0));
}

def code(x):
	return (1.0 / (x + 1.0)) - (1.0 / (x - 1.0))

function code(x)
	return Float64(Float64(1.0 / Float64(x + 1.0)) - Float64(1.0 / Float64(x - 1.0)))
end

function tmp = code(x)
	tmp = (1.0 / (x + 1.0)) - (1.0 / (x - 1.0));
end

code[x_] := N[(N[(1.0 / N[(x + 1.0), $MachinePrecision]), $MachinePrecision] - N[(1.0 / N[(x - 1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]

\begin{array}{l}

\\
\frac{1}{x + 1} - \frac{1}{x - 1}
\end{array}

Reproduce

herbie shell --seed 2024012 
(FPCore (x)
  :name "Asymptote A"
  :precision binary64
  (- (/ 1.0 (+ x 1.0)) (/ 1.0 (- x 1.0))))

Please file a bug report with this information.

Backtrace

car: contract violation expected: pair? given: '#(#s(si 6 140) (#s(si 1 134)))		L	C
err-lsts->split-indices	/home/nightlies/herbie/zane-regimes-2/src/core/regimes.rkt	176	0
option-on-expr	/home/nightlies/herbie/zane-regimes-2/src/core/regimes.rkt	106	0
infer-splitpoints	/home/nightlies/herbie/zane-regimes-2/src/core/regimes.rkt	39	0
loop	/home/nightlies/herbie/zane-regimes-2/src/core/regimes.rkt	27	2
loop	/home/nightlies/herbie/zane-regimes-2/src/core/regimes.rkt	27	2
loop	/home/nightlies/herbie/zane-regimes-2/src/core/regimes.rkt	27	2
loop	/home/nightlies/herbie/zane-regimes-2/src/core/regimes.rkt	27	2
extract!	/home/nightlies/herbie/zane-regimes-2/src/mainloop.rkt	352	0
run-improve!	/home/nightlies/herbie/zane-regimes-2/src/mainloop.rkt	326	0
get-alternatives/report	/home/nightlies/herbie/zane-regimes-2/src/sandbox.rkt	150	0
(unnamed)	/home/nightlies/herbie/zane-regimes-2/src/sandbox.rkt	246	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