\[2 \cdot \left(\left(1 \cdot \frac{1}{9} + \frac{1}{9} \cdot \frac{1}{9}\right) + \frac{1}{9} \cdot 1\right)\]
2 \cdot \left(\left(1 \cdot \frac{1}{9} + \frac{1}{9} \cdot \frac{1}{9}\right) + \frac{1}{9} \cdot 1\right)
double f() {
        double r72231 = 2.0;
        double r72232 = 1.0;
        double r72233 = 9.0;
        double r72234 = r72232 / r72233;
        double r72235 = r72232 * r72234;
        double r72236 = r72234 * r72234;
        double r72237 = r72235 + r72236;
        double r72238 = r72234 * r72232;
        double r72239 = r72237 + r72238;
        double r72240 = r72231 * r72239;
        return r72240;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019196 
(FPCore ()
  :name "Rectangular parallelepiped of dimension a×b×c"

  :herbie-target
  (+ (+ (* (* (/ 1.0 9.0) 1.0) 2.0) (* 2.0 (* (/ 1.0 9.0) (/ 1.0 9.0)))) (* 2.0 (* 1.0 (/ 1.0 9.0))))

  (* 2.0 (+ (+ (* 1.0 (/ 1.0 9.0)) (* (/ 1.0 9.0) (/ 1.0 9.0))) (* (/ 1.0 9.0) 1.0))))

Backtrace

car: contract violation expected: pair? given: '()LC
loop/data/pavpan/nightlies/herbie/master/src/points.rkt1224
prepare-points/data/pavpan/nightlies/herbie/master/src/points.rkt1460
run-improve47/data/pavpan/nightlies/herbie/master/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