\[\left(\left(x - \left(y + 0.5\right) \cdot \log y\right) + y\right) - z\]
\left(\left(x - \left(y + 0.5\right) \cdot \log y\right) + y\right) - z
double f(double x, double y, double z) {
        double r43832069 = x;
        double r43832070 = y;
        double r43832071 = 0.5;
        double r43832072 = r43832070 + r43832071;
        double r43832073 = log(r43832070);
        double r43832074 = r43832072 * r43832073;
        double r43832075 = r43832069 - r43832074;
        double r43832076 = r43832075 + r43832070;
        double r43832077 = z;
        double r43832078 = r43832076 - r43832077;
        return r43832078;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019173 +o rules:numerics
(FPCore (x y z)
  :name "Numeric.SpecFunctions:stirlingError from math-functions-0.1.5.2"

  :herbie-target
  (- (- (+ y x) z) (* (+ y 0.5) (log y)))

  (- (+ (- x (* (+ y 0.5) (log y))) y) z))

Backtrace

hash-ref: no value found for key key: #<enode 629(629)>LC
for-loop/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt1972
extractor-extract/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt1960
for-loop/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt352
(unnamed)/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt260
simplify!/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt2170
run-iter!/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt3200
for-loop/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt3544
run-improve43/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt3390
(unnamed)/opt/racket-7.0/collects/racket/private/more-scheme.rkt26128
run/opt/racket-7.0/share/pkgs/profile-lib/main.rkt392
profile-thunk16/opt/racket-7.0/share/pkgs/profile-lib/main.rkt90
(unnamed)/opt/racket-7.0/collects/racket/private/more-scheme.rkt26128