\[\sqrt{\left(\left(2 \cdot n\right) \cdot U\right) \cdot \left(\left(t - 2 \cdot \frac{\ell \cdot \ell}{Om}\right) - \left(n \cdot {\left(\frac{\ell}{Om}\right)}^{2}\right) \cdot \left(U - U*\right)\right)}\]

\sqrt{\left(\left(2 \cdot n\right) \cdot U\right) \cdot \left(\left(t - 2 \cdot \frac{\ell \cdot \ell}{Om}\right) - \left(n \cdot {\left(\frac{\ell}{Om}\right)}^{2}\right) \cdot \left(U - U*\right)\right)}

double f(double n, double U, double t, double l, double Om, double U_) {
        double r8145 = 2.0;
        double r8146 = n;
        double r8147 = r8145 * r8146;
        double r8148 = U;
        double r8149 = r8147 * r8148;
        double r8150 = t;
        double r8151 = l;
        double r8152 = r8151 * r8151;
        double r8153 = Om;
        double r8154 = r8152 / r8153;
        double r8155 = r8145 * r8154;
        double r8156 = r8150 - r8155;
        double r8157 = r8151 / r8153;
        double r8158 = pow(r8157, r8145);
        double r8159 = r8146 * r8158;
        double r8160 = U_;
        double r8161 = r8148 - r8160;
        double r8162 = r8159 * r8161;
        double r8163 = r8156 - r8162;
        double r8164 = r8149 * r8163;
        double r8165 = sqrt(r8164);
        return r8165;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019179 
(FPCore (n U t l Om U*)
  :name "Toniolo and Linder, Equation (13)"
  (sqrt (* (* (* 2.0 n) U) (- (- t (* 2.0 (/ (* l l) Om))) (* (* n (pow (/ l Om) 2.0)) (- U U*))))))

Backtrace

result arity mismatch; expected number of values not received expected: 2 received: 1 in: local-binding form values...: 0		L	C
loop	/data/pavpan/nightlies/herbie/various-cleanup/src/core/extraction.rkt	25	2
(unnamed)	/data/pavpan/nightlies/herbie/various-cleanup/src/core/simplify.rkt	26	0
simplify!	/data/pavpan/nightlies/herbie/various-cleanup/src/mainloop.rkt	217	0
run-improve43	/data/pavpan/nightlies/herbie/various-cleanup/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