\[\frac{\tan^{-1}_* \frac{im}{re} \cdot \log base - \log \left(\sqrt{re \cdot re + im \cdot im}\right) \cdot 0.0}{\log base \cdot \log base + 0.0 \cdot 0.0}\]
\frac{\tan^{-1}_* \frac{im}{re} \cdot \log base - \log \left(\sqrt{re \cdot re + im \cdot im}\right) \cdot 0.0}{\log base \cdot \log base + 0.0 \cdot 0.0}
double f(double re, double im, double base) {
        double r8168 = im;
        double r8169 = re;
        double r8170 = atan2(r8168, r8169);
        double r8171 = base;
        double r8172 = log(r8171);
        double r8173 = r8170 * r8172;
        double r8174 = r8169 * r8169;
        double r8175 = r8168 * r8168;
        double r8176 = r8174 + r8175;
        double r8177 = sqrt(r8176);
        double r8178 = log(r8177);
        double r8179 = 0.0;
        double r8180 = r8178 * r8179;
        double r8181 = r8173 - r8180;
        double r8182 = r8172 * r8172;
        double r8183 = r8179 * r8179;
        double r8184 = r8182 + r8183;
        double r8185 = r8181 / r8184;
        return r8185;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019194 
(FPCore (re im base)
  :name "math.log/2 on complex, imaginary part"
  (/ (- (* (atan2 im re) (log base)) (* (log (sqrt (+ (* re re) (* im im)))) 0.0)) (+ (* (log base) (log base)) (* 0.0 0.0))))

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.rkt2200
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