\[\left(0.5 \cdot \cos re\right) \cdot \left(e^{-im} + e^{im}\right) \]
(FPCore (re im)
 :precision binary64
 (* (* 0.5 (cos re)) (+ (exp (- im)) (exp im))))
double code(double re, double im) {
	return (0.5 * cos(re)) * (exp(-im) + exp(im));
}
real(8) function code(re, im)
    real(8), intent (in) :: re
    real(8), intent (in) :: im
    code = (0.5d0 * cos(re)) * (exp(-im) + exp(im))
end function
public static double code(double re, double im) {
	return (0.5 * Math.cos(re)) * (Math.exp(-im) + Math.exp(im));
}
def code(re, im):
	return (0.5 * math.cos(re)) * (math.exp(-im) + math.exp(im))
function code(re, im)
	return Float64(Float64(0.5 * cos(re)) * Float64(exp(Float64(-im)) + exp(im)))
end
function tmp = code(re, im)
	tmp = (0.5 * cos(re)) * (exp(-im) + exp(im));
end
code[re_, im_] := N[(N[(0.5 * N[Cos[re], $MachinePrecision]), $MachinePrecision] * N[(N[Exp[(-im)], $MachinePrecision] + N[Exp[im], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\left(0.5 \cdot \cos re\right) \cdot \left(e^{-im} + e^{im}\right)

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2022203 
(FPCore (re im)
  :name "math.cos on complex, real part"
  :precision binary64
  (* (* 0.5 (cos re)) (+ (exp (- im)) (exp im))))

Backtrace

hash-ref: no value found for key key: '~LC
get-parametric-operator/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/syntax.rkt2180
f336.../match/compiler.rkt54840
expand-parametric/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/sugar.rkt620
(unnamed)/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/rules.rkt1768
generate-rules-for/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/rules.rkt1610
generate-missing-rules/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/rules.rkt1870
(unnamed)/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/rules.rkt2926
get-swaps/data/pavpan/nightlies/herbie/enumo-rat/src/symmetry.rkt60
connected-components/data/pavpan/nightlies/herbie/enumo-rat/src/symmetry.rkt170
run-improve!/data/pavpan/nightlies/herbie/enumo-rat/src/mainloop.rkt2960
(unnamed)/data/pavpan/nightlies/herbie/enumo-rat/src/sandbox.rkt556
(unnamed)/usr/share/racket/pkgs/profile-lib/main.rkt4010
profile-thunk/usr/share/racket/pkgs/profile-lib/main.rkt90
(unnamed)/usr/share/racket/collects/racket/engine.rkt4224