Exception for Quotient of sum of exps

• could not determine a ground truth

  1. a = -2.00000000000000007e154
  2. b = -2.00000000000000007e154

Specification

Math

\[\begin{array}{l} \\ \frac{e^{a}}{e^{a} + e^{b}} \end{array} \]

FPCore

(FPCore (a b) :precision binary64 (/ (exp a) (+ (exp a) (exp b))))

C

double code(double a, double b) {
	return exp(a) / (exp(a) + exp(b));
}

Fortran

real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = exp(a) / (exp(a) + exp(b))
end function

Java

public static double code(double a, double b) {
	return Math.exp(a) / (Math.exp(a) + Math.exp(b));
}

Python

def code(a, b):
	return math.exp(a) / (math.exp(a) + math.exp(b))

Julia

function code(a, b)
	return Float64(exp(a) / Float64(exp(a) + exp(b)))
end

MATLAB

function tmp = code(a, b)
	tmp = exp(a) / (exp(a) + exp(b));
end

Wolfram

code[a_, b_] := N[(N[Exp[a], $MachinePrecision] / N[(N[Exp[a], $MachinePrecision] + N[Exp[b], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]

Reproduce

herbie shell --seed 2024039 
(FPCore (a b)
  :name "Quotient of sum of exps"
  :precision binary64

  :herbie-target
  (/ 1.0 (+ 1.0 (exp (- b a))))

  (/ (exp a) (+ (exp a) (exp b))))

Please file a bug report with this information.

Backtrace

member: not a proper list in: 1		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
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