\[\left(\left(-2 \cdot J\right) \cdot \cos \left(\frac{K}{2}\right)\right) \cdot \sqrt{1 + {\left(\frac{U}{\left(2 \cdot J\right) \cdot \cos \left(\frac{K}{2}\right)}\right)}^{2}}\]

\left(\left(-2 \cdot J\right) \cdot \cos \left(\frac{K}{2}\right)\right) \cdot \sqrt{1 + {\left(\frac{U}{\left(2 \cdot J\right) \cdot \cos \left(\frac{K}{2}\right)}\right)}^{2}}

double f(double J, double K, double U) {
        double r8337 = -2.0;
        double r8338 = J;
        double r8339 = r8337 * r8338;
        double r8340 = K;
        double r8341 = 2.0;
        double r8342 = r8340 / r8341;
        double r8343 = cos(r8342);
        double r8344 = r8339 * r8343;
        double r8345 = 1.0;
        double r8346 = U;
        double r8347 = r8341 * r8338;
        double r8348 = r8347 * r8343;
        double r8349 = r8346 / r8348;
        double r8350 = pow(r8349, r8341);
        double r8351 = r8345 + r8350;
        double r8352 = sqrt(r8351);
        double r8353 = r8344 * r8352;
        return r8353;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019191 
(FPCore (J K U)
  :name "Maksimov and Kolovsky, Equation (3)"
  (* (* (* -2.0 J) (cos (/ K 2.0))) (sqrt (+ 1.0 (pow (/ U (* (* 2.0 J) (cos (/ K 2.0)))) 2.0)))))

Backtrace

get-representation: Unknown representation #f		L	C
loop	/data/pavpan/nightlies/herbie/interface2/src/points.rkt	122	4
prepare-points	/data/pavpan/nightlies/herbie/interface2/src/points.rkt	146	0
setup-prog!34	/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt	67	0
run-improve43	/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt	339	0
(unnamed)	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	261	28
run	/opt/racket-7.0/share/pkgs/profile-lib/main.rkt	39	2
profile-thunk16	/opt/racket-7.0/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	261	28