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

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2022150 
(FPCore (re im)
  :name "math.cos on complex, imaginary part"
  :precision binary64

  :herbie-target
  (if (< (fabs im) 1.0) (- (* (sin re) (+ (+ im (* (* (* 0.16666666666666666 im) im) im)) (* (* (* (* (* 0.008333333333333333 im) im) im) im) im)))) (* (* 0.5 (sin re)) (- (exp (- im)) (exp im))))

  (* (* 0.5 (sin re)) (- (exp (- im)) (exp im))))

Backtrace

application: required keyword argument not supplied procedure: batch-egg-rewrite required keyword: #:rules arguments...: '(#<rule erfc-erf_binary64> #<rule erf-erfc_binary64> #<rule erf-odd_binary64> #<rule prod-diff_binary64> #<rule hypot-udef_binary64> #<rule expm1-log1p-u_binary64> #<rule log1p-expm1-u_binary64> #<rule log1p-udef_binary64> #<rule expm1-udef_binary64> #... #:depths '(1 1) #:roots '((2) (2))LC
(unnamed)/opt/racket-8.1/collects/racket/private/kw.rkt155814
rewrite-expressions/data/pavpan/nightlies/herbie/timeline/src/core/matcher.rkt1710
gen-rewrites!/data/pavpan/nightlies/herbie/timeline/src/patch.rkt1440
patch-table-run/data/pavpan/nightlies/herbie/timeline/src/patch.rkt2910
(unnamed)/opt/racket-8.1/collects/racket/contract/private/arrow-val-first.rkt48618
run-iter!/data/pavpan/nightlies/herbie/timeline/src/mainloop.rkt2460
mutate!/data/pavpan/nightlies/herbie/timeline/src/mainloop.rkt3790
run-improve!/data/pavpan/nightlies/herbie/timeline/src/mainloop.rkt3260
(unnamed)/data/pavpan/nightlies/herbie/timeline/src/sandbox.rkt666
(unnamed)/opt/racket-8.1/share/pkgs/profile-lib/main.rkt4010
profile-thunk/opt/racket-8.1/share/pkgs/profile-lib/main.rkt90
(unnamed)/opt/racket-8.1/collects/racket/engine.rkt4224