\[\frac{2}{\left(\left(\frac{{t}^{3}}{\ell \cdot \ell} \cdot \sin k\right) \cdot \tan k\right) \cdot \left(\left(1 + {\left(\frac{k}{t}\right)}^{2}\right) - 1\right)}\]
\frac{2}{\left(\left(\frac{{t}^{3}}{\ell \cdot \ell} \cdot \sin k\right) \cdot \tan k\right) \cdot \left(\left(1 + {\left(\frac{k}{t}\right)}^{2}\right) - 1\right)}
double f(double t, double l, double k) {
        double r8248 = 2.0;
        double r8249 = t;
        double r8250 = 3.0;
        double r8251 = pow(r8249, r8250);
        double r8252 = l;
        double r8253 = r8252 * r8252;
        double r8254 = r8251 / r8253;
        double r8255 = k;
        double r8256 = sin(r8255);
        double r8257 = r8254 * r8256;
        double r8258 = tan(r8255);
        double r8259 = r8257 * r8258;
        double r8260 = 1.0;
        double r8261 = r8255 / r8249;
        double r8262 = pow(r8261, r8248);
        double r8263 = r8260 + r8262;
        double r8264 = r8263 - r8260;
        double r8265 = r8259 * r8264;
        double r8266 = r8248 / r8265;
        return r8266;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019179 
(FPCore (t l k)
  :name "Toniolo and Linder, Equation (10-)"
  (/ 2.0 (* (* (* (/ (pow t 3.0) (* l l)) (sin k)) (tan k)) (- (+ 1.0 (pow (/ k t) 2.0)) 1.0))))

Backtrace

result arity mismatch; expected number of values not received expected: 2 received: 1 in: local-binding form values...: 0LC
loop/data/pavpan/nightlies/herbie/various-cleanup/src/core/extraction.rkt252
(unnamed)/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt260
simplify!/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt2170
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