\[\left(\left(\left(\sqrt{x + 1} - \sqrt{x}\right) + \left(\sqrt{y + 1} - \sqrt{y}\right)\right) + \left(\sqrt{z + 1} - \sqrt{z}\right)\right) + \left(\sqrt{t + 1} - \sqrt{t}\right)\]

\left(\left(\left(\sqrt{x + 1} - \sqrt{x}\right) + \left(\sqrt{y + 1} - \sqrt{y}\right)\right) + \left(\sqrt{z + 1} - \sqrt{z}\right)\right) + \left(\sqrt{t + 1} - \sqrt{t}\right)

double f(double x, double y, double z, double t) {
        double r321092 = x;
        double r321093 = 1.0;
        double r321094 = r321092 + r321093;
        double r321095 = sqrt(r321094);
        double r321096 = sqrt(r321092);
        double r321097 = r321095 - r321096;
        double r321098 = y;
        double r321099 = r321098 + r321093;
        double r321100 = sqrt(r321099);
        double r321101 = sqrt(r321098);
        double r321102 = r321100 - r321101;
        double r321103 = r321097 + r321102;
        double r321104 = z;
        double r321105 = r321104 + r321093;
        double r321106 = sqrt(r321105);
        double r321107 = sqrt(r321104);
        double r321108 = r321106 - r321107;
        double r321109 = r321103 + r321108;
        double r321110 = t;
        double r321111 = r321110 + r321093;
        double r321112 = sqrt(r321111);
        double r321113 = sqrt(r321110);
        double r321114 = r321112 - r321113;
        double r321115 = r321109 + r321114;
        return r321115;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019323 
(FPCore (x y z t)
  :name "Main:z from "
  :precision binary64

  :herbie-target
  (+ (+ (+ (/ 1 (+ (sqrt (+ x 1)) (sqrt x))) (/ 1 (+ (sqrt (+ y 1)) (sqrt y)))) (/ 1 (+ (sqrt (+ z 1)) (sqrt z)))) (- (sqrt (+ t 1)) (sqrt t)))

  (+ (+ (+ (- (sqrt (+ x 1)) (sqrt x)) (- (sqrt (+ y 1)) (sqrt y))) (- (sqrt (+ z 1)) (sqrt z))) (- (sqrt (+ t 1)) (sqrt t))))

Backtrace

get-representation: Unknown representation real		L	C
(unnamed)	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/regimes.rkt	65	3
filter	/opt/racket-7.2/collects/racket/private/list.rkt	256	2
infer-splitpoints	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/regimes.rkt	34	0
get-final-combination	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	369	0
(unnamed)	/opt/racket-7.2/collects/racket/private/more-scheme.rkt	261	28
run	/opt/racket-7.2/share/pkgs/profile-lib/main.rkt	39	2
profile-thunk16	/opt/racket-7.2/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/opt/racket-7.2/collects/racket/private/more-scheme.rkt	261	28