\[\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}\]
\frac{1}{\sqrt{k}} \cdot {\left(\left(2 \cdot \pi\right) \cdot n\right)}^{\left(\frac{1 - k}{2}\right)}
double f(double k, double n) {
        double r36195 = 1.0;
        double r36196 = k;
        double r36197 = sqrt(r36196);
        double r36198 = r36195 / r36197;
        double r36199 = 2.0;
        double r36200 = atan2(1.0, 0.0);
        double r36201 = r36199 * r36200;
        double r36202 = n;
        double r36203 = r36201 * r36202;
        double r36204 = r36195 - r36196;
        double r36205 = r36204 / r36199;
        double r36206 = pow(r36203, r36205);
        double r36207 = r36198 * r36206;
        return r36207;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019195 
(FPCore (k n)
  :name "Migdal et al, Equation (51)"
  (* (/ 1.0 (sqrt k)) (pow (* (* 2.0 PI) n) (/ (- 1.0 k) 2.0))))

Backtrace

get-representation: Unknown representation #fLC
(unnamed)/data/pavpan/nightlies/herbie/various-cleanup/src/core/localize.rkt2313
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
map/opt/racket-7.0/collects/racket/private/map.rkt3513
parse-loop30/opt/racket-7.0/collects/racket/match/compiler.rkt41815
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
map/opt/racket-7.0/collects/racket/private/map.rkt3513
parse-loop30/opt/racket-7.0/collects/racket/match/compiler.rkt41815
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
map/opt/racket-7.0/collects/racket/private/map.rkt3513
parse-loop30/opt/racket-7.0/collects/racket/match/compiler.rkt41815
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
map/opt/racket-7.0/collects/racket/private/map.rkt3513
parse-loop30/opt/racket-7.0/collects/racket/match/compiler.rkt41815
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
localize-error/data/pavpan/nightlies/herbie/various-cleanup/src/core/localize.rkt610
localize!/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt1230
run-iter!/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt3230
for-loop/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt3594
run-improve47/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt3420
(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