Exception for quadp (p42, positive)

Specification

Math

\[\begin{array}{l} \\ \frac{\left(-b\right) + \sqrt{b \cdot b - 4 \cdot \left(a \cdot c\right)}}{2 \cdot a} \end{array} \]

FPCore

(FPCore (a b c)
 :precision binary64
 (/ (+ (- b) (sqrt (- (* b b) (* 4.0 (* a c))))) (* 2.0 a)))

C

double code(double a, double b, double c) {
	return (-b + sqrt(((b * b) - (4.0 * (a * c))))) / (2.0 * a);
}

Fortran

real(8) function code(a, b, c)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8), intent (in) :: c
    code = (-b + sqrt(((b * b) - (4.0d0 * (a * c))))) / (2.0d0 * a)
end function

Java

public static double code(double a, double b, double c) {
	return (-b + Math.sqrt(((b * b) - (4.0 * (a * c))))) / (2.0 * a);
}

Python

def code(a, b, c):
	return (-b + math.sqrt(((b * b) - (4.0 * (a * c))))) / (2.0 * a)

Julia

function code(a, b, c)
	return Float64(Float64(Float64(-b) + sqrt(Float64(Float64(b * b) - Float64(4.0 * Float64(a * c))))) / Float64(2.0 * a))
end

MATLAB

function tmp = code(a, b, c)
	tmp = (-b + sqrt(((b * b) - (4.0 * (a * c))))) / (2.0 * a);
end

Wolfram

code[a_, b_, c_] := N[(N[((-b) + N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(4.0 * N[(a * c), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(2.0 * a), $MachinePrecision]), $MachinePrecision]

Reproduce

herbie shell --seed 2024039 
(FPCore (a b c)
  :name "quadp (p42, positive)"
  :precision binary64
  :herbie-expected 10

  :herbie-target
  (if (< b 0.0) (/ (- (if (== (copysign a c) a) (* (sqrt (- (fabs (/ b 2.0)) (* (sqrt (fabs a)) (sqrt (fabs c))))) (sqrt (+ (fabs (/ b 2.0)) (* (sqrt (fabs a)) (sqrt (fabs c)))))) (hypot (/ b 2.0) (* (sqrt (fabs a)) (sqrt (fabs c))))) (/ b 2.0)) a) (/ (- c) (+ (/ b 2.0) (if (== (copysign a c) a) (* (sqrt (- (fabs (/ b 2.0)) (* (sqrt (fabs a)) (sqrt (fabs c))))) (sqrt (+ (fabs (/ b 2.0)) (* (sqrt (fabs a)) (sqrt (fabs c)))))) (hypot (/ b 2.0) (* (sqrt (fabs a)) (sqrt (fabs c))))))))

  (/ (+ (- b) (sqrt (- (* b b) (* 4.0 (* a c))))) (* 2.0 a)))

Please file a bug report with this information.

Backtrace

member: not a proper list in: 2		L	C
gather-multiplicative-terms	/home/nightlies/herbie/sound-rules/src/core/reduce.rkt	125	0
simplify-node*	/home/nightlies/herbie/sound-rules/src/core/reduce.rkt	84	0
hash-ref!	/usr/local/racket/collects/racket/private/more-scheme.rkt	377	2
hash-ref!	/usr/local/racket/collects/racket/private/more-scheme.rkt	377	2
taylor-sqrt	/home/nightlies/herbie/sound-rules/src/core/taylor.rkt	295	0
hash-ref!	/usr/local/racket/collects/racket/private/more-scheme.rkt	377	2
approximate	/home/nightlies/herbie/sound-rules/src/core/taylor.rkt	7	0
taylor-expr	/home/nightlies/herbie/sound-rules/src/patch.rkt	89	0
taylor-alt	/home/nightlies/herbie/sound-rules/src/patch.rkt	96	0
gen-series!	/home/nightlies/herbie/sound-rules/src/patch.rkt	109	0
patch-table-run	/home/nightlies/herbie/sound-rules/src/patch.rkt	257	0
(unnamed)	/usr/local/racket/collects/racket/contract/private/arrow-val-first.rkt	486	18
run-iter!	/home/nightlies/herbie/sound-rules/src/mainloop.rkt	288	0
mutate!	/home/nightlies/herbie/sound-rules/src/mainloop.rkt	340	0
run-improve!	/home/nightlies/herbie/sound-rules/src/mainloop.rkt	326	0
get-alternatives/report	/home/nightlies/herbie/sound-rules/src/sandbox.rkt	169	0
(unnamed)	/home/nightlies/herbie/sound-rules/src/sandbox.rkt	262	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