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

\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 r345527 = x;
        double r345528 = 1.0;
        double r345529 = r345527 + r345528;
        double r345530 = sqrt(r345529);
        double r345531 = sqrt(r345527);
        double r345532 = r345530 - r345531;
        double r345533 = y;
        double r345534 = r345533 + r345528;
        double r345535 = sqrt(r345534);
        double r345536 = sqrt(r345533);
        double r345537 = r345535 - r345536;
        double r345538 = r345532 + r345537;
        double r345539 = z;
        double r345540 = r345539 + r345528;
        double r345541 = sqrt(r345540);
        double r345542 = sqrt(r345539);
        double r345543 = r345541 - r345542;
        double r345544 = r345538 + r345543;
        double r345545 = t;
        double r345546 = r345545 + r345528;
        double r345547 = sqrt(r345546);
        double r345548 = sqrt(r345545);
        double r345549 = r345547 - r345548;
        double r345550 = r345544 + r345549;
        return r345550;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019323 +o rules:numerics
(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