Exception for 2cos (problem 3.3.5)

Specification

\[\left(\left(-10000 \leq x \land x \leq 10000\right) \land 10^{-16} \cdot \left|x\right| < \varepsilon\right) \land \varepsilon < \left|x\right|\]

Math

\[\begin{array}{l} \\ \cos \left(x + \varepsilon\right) - \cos x \end{array} \]

FPCore

(FPCore (x eps) :precision binary64 (- (cos (+ x eps)) (cos x)))

C

double code(double x, double eps) {
	return cos((x + eps)) - cos(x);
}

Fortran

real(8) function code(x, eps)
    real(8), intent (in) :: x
    real(8), intent (in) :: eps
    code = cos((x + eps)) - cos(x)
end function

Java

public static double code(double x, double eps) {
	return Math.cos((x + eps)) - Math.cos(x);
}

Python

def code(x, eps):
	return math.cos((x + eps)) - math.cos(x)

Julia

function code(x, eps)
	return Float64(cos(Float64(x + eps)) - cos(x))
end

MATLAB

function tmp = code(x, eps)
	tmp = cos((x + eps)) - cos(x);
end

Wolfram

code[x_, eps_] := N[(N[Cos[N[(x + eps), $MachinePrecision]], $MachinePrecision] - N[Cos[x], $MachinePrecision]), $MachinePrecision]

Reproduce

herbie shell --seed 2024170 
(FPCore (x eps)
  :name "2cos (problem 3.3.5)"
  :precision binary64
  :pre (and (and (and (<= -10000.0 x) (<= x 10000.0)) (< (* 1e-16 (fabs x)) eps)) (< eps (fabs x)))

  :alt
  (! :herbie-platform default (* -2 (sin (+ x (/ eps 2))) (sin (/ eps 2))))

  (- (cos (+ x eps)) (cos x)))

Please file a bug report with this information.

Backtrace

timeline-push!: contract violation expected: jsexpr? given: '#hash((#t . 0.2528600429650396) (unknown . 0.2528600429650396) (precondition . 0.4942799140699208) (valid . 0.0)) in: the repeated argument of (-> symbol? jsexpr? ... void?) contract from: <pkgs>/herbie/timeline.rkt blaming: <pkgs>/herbie/searchreals.rkt (assuming the contract is correct) at: <pkgs>/herbie/timeline.rkt:10:3		L	C
raise-blame-error	/usr/local/racket/collects/racket/contract/private/blame.rkt	346	0
loop	/usr/local/racket/collects/racket/contract/private/list.rkt	991	12
(unnamed)	.../private/arrow-val-first.rkt	486	18
find-intervals	/home/nightlies/herbie/zane-job-abstraction3/src/searchreals.rkt	86	0
make-sampler	/home/nightlies/herbie/zane-job-abstraction3/src/sampling.rkt	110	0
sample-points	/home/nightlies/herbie/zane-job-abstraction3/src/sampling.rkt	244	0
setup-context!	/home/nightlies/herbie/zane-job-abstraction3/src/mainloop.rkt	45	0
get-alternatives/report	/home/nightlies/herbie/zane-job-abstraction3/src/sandbox.rkt	166	0
(unnamed)	/home/nightlies/herbie/zane-job-abstraction3/src/sandbox.rkt	260	6
(unnamed)	/usr/local/racket/share/pkgs/profile-lib/main.rkt	40	10
profile-thunk	/usr/local/racket/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/usr/local/racket/collects/racket/engine.rkt	42	24