Exception for Logistic function

Specification

\[0 \leq s \land s \leq 1.0651631\]

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

(FPCore (x s) :precision binary32 (/ 1.0 (+ 1.0 (exp (/ (- x) s)))))

float code(float x, float s) {
	return 1.0f / (1.0f + expf((-x / s)));
}

real(4) function code(x, s)
    real(4), intent (in) :: x
    real(4), intent (in) :: s
    code = 1.0e0 / (1.0e0 + exp((-x / s)))
end function

function code(x, s)
	return Float32(Float32(1.0) / Float32(Float32(1.0) + exp(Float32(Float32(-x) / s))))
end

function tmp = code(x, s)
	tmp = single(1.0) / (single(1.0) + exp((-x / s)));
end

\begin{array}{l}

\\
\frac{1}{1 + e^{\frac{-x}{s}}}
\end{array}

Reproduce

herbie shell --seed 2024196 
(FPCore (x s)
  :name "Logistic function"
  :precision binary32
  :pre (and (<= 0.0 s) (<= s 1.0651631))
  (/ 1.0 (+ 1.0 (exp (/ (- x) s)))))

Please file a bug report with this information.

Backtrace

vector-set!: contract violation expected: exact-nonnegative-integer? given: -2 argument position: 2nd first argument...: '#(#f #t #t #t #t #t #t #t #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f)		L	C
backward-pass	/home/nightlies/rival/main/eval/adjust.rkt	8	0
rival-machine-adjust	/home/nightlies/rival/main/eval/run.rkt	98	0
rival-machine-full	/home/nightlies/rival/main/eval/main.rkt	16	0
rival-apply	/home/nightlies/rival/main/eval/main.rkt	56	0
(unnamed)	/usr/local/racket/collects/racket/contract/private/arrow-val-first.rkt	486	18
(unnamed)	/home/nightlies/herbie/zane-odyssey-timeline/src/sampling.rkt	159	4
ival-eval	/home/nightlies/herbie/zane-odyssey-timeline/src/sampling.rkt	153	0
<eval-prog-real>	/home/nightlies/herbie/zane-odyssey-timeline/src/sampling.rkt	188	2
compute-local-errors	/home/nightlies/herbie/zane-odyssey-timeline/src/core/localize.rkt	105	0
batch-localize-errors	/home/nightlies/herbie/zane-odyssey-timeline/src/core/localize.rkt	91	0
localize!	/home/nightlies/herbie/zane-odyssey-timeline/src/mainloop.rkt	187	0
run-iter!	/home/nightlies/herbie/zane-odyssey-timeline/src/mainloop.rkt	70	0
mutate!	/home/nightlies/herbie/zane-odyssey-timeline/src/mainloop.rkt	62	0
run-improve!	/home/nightlies/herbie/zane-odyssey-timeline/src/mainloop.rkt	48	0
get-alternatives/report	/home/nightlies/herbie/zane-odyssey-timeline/src/sandbox.rkt	167	0
(unnamed)	/home/nightlies/herbie/zane-odyssey-timeline/src/sandbox.rkt	261	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