\[x + \left(y - z\right) \cdot \frac{t - x}{a - z}\]
x + \left(y - z\right) \cdot \frac{t - x}{a - z}
double f(double x, double y, double z, double t, double a) {
        double r8084 = x;
        double r8085 = y;
        double r8086 = z;
        double r8087 = r8085 - r8086;
        double r8088 = t;
        double r8089 = r8088 - r8084;
        double r8090 = a;
        double r8091 = r8090 - r8086;
        double r8092 = r8089 / r8091;
        double r8093 = r8087 * r8092;
        double r8094 = r8084 + r8093;
        return r8094;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019191 
(FPCore (x y z t a)
  :name "Numeric.Signal:interpolate   from hsignal-0.2.7.1"
  (+ x (* (- y z) (/ (- t x) (- a z)))))

Backtrace

get-representation: Unknown representation #fLC
loop/data/pavpan/nightlies/herbie/interface2/src/points.rkt1224
prepare-points/data/pavpan/nightlies/herbie/interface2/src/points.rkt1460
setup-prog!34/data/pavpan/nightlies/herbie/interface2/src/mainloop.rkt670
run-improve43/data/pavpan/nightlies/herbie/interface2/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