Exception for 2isqrt (example 3.6)

Math

\[\frac{1}{\sqrt{x}} - \frac{1}{\sqrt{x + 1}} \]

FPCore

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

C

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

Fortran

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

Java

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

Python

def code(x):
	return (1.0 / math.sqrt(x)) - (1.0 / math.sqrt((x + 1.0)))

Julia

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

MATLAB

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

Wolfram

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

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2023033 
(FPCore (x)
  :name "2isqrt (example 3.6)"
  :precision binary64

  :herbie-target
  (/ 1.0 (+ (* (+ x 1.0) (sqrt x)) (* x (sqrt (+ x 1.0)))))

  (- (/ 1.0 (sqrt x)) (/ 1.0 (sqrt (+ x 1.0)))))

Backtrace

map: contract violation expected: list? given: #<eof>		L	C
gen-map	/usr/share/racket/collects/racket/private/map.rkt	257	2
run-egglog	/home/nightlies/herbie/oflatt-egglog-ctx/src/egglog/run-egglog.rkt	1456	0
run-simplify-input	/home/nightlies/herbie/oflatt-egglog-ctx/src/core/simplify.rkt	73	0
simplify-batch	/home/nightlies/herbie/oflatt-egglog-ctx/src/core/simplify.rkt	48	0
(unnamed)	/usr/share/racket/collects/racket/contract/private/arrow-higher-order.rkt	379	33
simplify!	/home/nightlies/herbie/oflatt-egglog-ctx/src/patch.rkt	246	0
patch-table-run	/home/nightlies/herbie/oflatt-egglog-ctx/src/patch.rkt	318	0
(unnamed)	/usr/share/racket/collects/racket/contract/private/arrow-val-first.rkt	486	18
run-iter!	/home/nightlies/herbie/oflatt-egglog-ctx/src/mainloop.rkt	262	0
mutate!	/home/nightlies/herbie/oflatt-egglog-ctx/src/mainloop.rkt	372	0
run-improve!	/home/nightlies/herbie/oflatt-egglog-ctx/src/mainloop.rkt	320	0
run-herbie	/home/nightlies/herbie/oflatt-egglog-ctx/src/sandbox.rkt	57	0
(unnamed)	/home/nightlies/herbie/oflatt-egglog-ctx/src/sandbox.rkt	133	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