\[x - \frac{y - z}{\frac{\left(t - z\right) + 1}{a}}\]
x - \frac{y - z}{\frac{\left(t - z\right) + 1}{a}}
double f(double x, double y, double z, double t, double a) {
        double r9051 = x;
        double r9052 = y;
        double r9053 = z;
        double r9054 = r9052 - r9053;
        double r9055 = t;
        double r9056 = r9055 - r9053;
        double r9057 = 1.0;
        double r9058 = r9056 + r9057;
        double r9059 = a;
        double r9060 = r9058 / r9059;
        double r9061 = r9054 / r9060;
        double r9062 = r9051 - r9061;
        return r9062;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019194 
(FPCore (x y z t a)
  :name "Graphics.Rendering.Chart.SparkLine:renderSparkLine from Chart-1.5.3"

  :herbie-target
  (- x (* (/ (- y z) (+ (- t z) 1.0)) a))

  (- x (/ (- y z) (/ (+ (- t z) 1.0) a))))

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