\[x + \frac{\left(y - x\right) \cdot \left(z - t\right)}{a - t}\]
x + \frac{\left(y - x\right) \cdot \left(z - t\right)}{a - t}
double f(double x, double y, double z, double t, double a) {
        double r9136 = x;
        double r9137 = y;
        double r9138 = r9137 - r9136;
        double r9139 = z;
        double r9140 = t;
        double r9141 = r9139 - r9140;
        double r9142 = r9138 * r9141;
        double r9143 = a;
        double r9144 = r9143 - r9140;
        double r9145 = r9142 / r9144;
        double r9146 = r9136 + r9145;
        return r9146;
}

Reproduce

Please include this information when filing a bug report:

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

  :herbie-target
  (if (< a -1.6153062845442575e-142) (+ x (* (/ (- y x) 1.0) (/ (- z t) (- a t)))) (if (< a 3.774403170083174e-182) (- y (* (/ z t) (- y x))) (+ x (* (/ (- y x) 1.0) (/ (- z t) (- a t))))))

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

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