Exception for Ian Simplification

Specification

Math

\[\begin{array}{l} \\ \frac{\pi}{2} - 2 \cdot \sin^{-1} \left(\sqrt{\frac{1 - x}{2}}\right) \end{array} \]

FPCore

(FPCore (x)
 :precision binary64
 (- (/ PI 2.0) (* 2.0 (asin (sqrt (/ (- 1.0 x) 2.0))))))

C

double code(double x) {
	return (((double) M_PI) / 2.0) - (2.0 * asin(sqrt(((1.0 - x) / 2.0))));
}

Java

public static double code(double x) {
	return (Math.PI / 2.0) - (2.0 * Math.asin(Math.sqrt(((1.0 - x) / 2.0))));
}

Python

def code(x):
	return (math.pi / 2.0) - (2.0 * math.asin(math.sqrt(((1.0 - x) / 2.0))))

Julia

function code(x)
	return Float64(Float64(pi / 2.0) - Float64(2.0 * asin(sqrt(Float64(Float64(1.0 - x) / 2.0)))))
end

MATLAB

function tmp = code(x)
	tmp = (pi / 2.0) - (2.0 * asin(sqrt(((1.0 - x) / 2.0))));
end

Wolfram

code[x_] := N[(N[(Pi / 2.0), $MachinePrecision] - N[(2.0 * N[ArcSin[N[Sqrt[N[(N[(1.0 - x), $MachinePrecision] / 2.0), $MachinePrecision]], $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]

Reproduce

herbie shell --seed 2024196 
(FPCore (x)
  :name "Ian Simplification"
  :precision binary64

  :alt
  (! :herbie-platform default (asin x))

  (- (/ PI 2.0) (* 2.0 (asin (sqrt (/ (- 1.0 x) 2.0))))))

Please file a bug report with this information.

Backtrace

vector-set!: contract violation expected: exact-nonnegative-integer? given: -1 argument position: 2nd first argument...: '#(#f #t #t #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
predict-errors	/home/nightlies/herbie/zane-odyssey-timeline/src/explain.rkt	86	0
explain	/home/nightlies/herbie/zane-odyssey-timeline/src/explain.rkt	736	0
explain!	/home/nightlies/herbie/zane-odyssey-timeline/src/mainloop.rkt	339	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