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

\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 r192636 = x;
        double r192637 = 1.0;
        double r192638 = r192636 + r192637;
        double r192639 = sqrt(r192638);
        double r192640 = sqrt(r192636);
        double r192641 = r192639 - r192640;
        double r192642 = y;
        double r192643 = r192642 + r192637;
        double r192644 = sqrt(r192643);
        double r192645 = sqrt(r192642);
        double r192646 = r192644 - r192645;
        double r192647 = r192641 + r192646;
        double r192648 = z;
        double r192649 = r192648 + r192637;
        double r192650 = sqrt(r192649);
        double r192651 = sqrt(r192648);
        double r192652 = r192650 - r192651;
        double r192653 = r192647 + r192652;
        double r192654 = t;
        double r192655 = r192654 + r192637;
        double r192656 = sqrt(r192655);
        double r192657 = sqrt(r192654);
        double r192658 = r192656 - r192657;
        double r192659 = r192653 + r192658;
        return r192659;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2020045 
(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

hash-ref: no value found for key key: '(* #<enode 0(439)> #<enode 135(135)>)		L	C
for-loop	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/egraph.rkt	270	6
update-leader!	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/egraph.rkt	265	0
for-loop	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/main.rkt	77	2
prune-phase	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding/regraph/main.rkt	74	0
for-loop	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/core/simplify.rkt	80	4
for-loop	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/core/simplify.rkt	76	2
(unnamed)	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/core/simplify.rkt	56	0
(unnamed)	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/core/simplify.rkt	38	0
simplify!	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/mainloop.rkt	224	0
run-iter!	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/mainloop.rkt	327	0
for-loop	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/mainloop.rkt	365	4
run-improve47	/data/pavpan/nightlies/herbie/simplify-regraph-rebuilding-2/src/mainloop.rkt	346	0
.../more-scheme.rkt:261:28	unknown
run	/opt/racket-7.5/share/pkgs/profile-lib/main.rkt	39	2
profile-thunk16	/opt/racket-7.5/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/opt/racket-7.5/collects/racket/private/more-scheme.rkt	261	28

Falling back on racket egraph because egg-herbie package not installed (more)

Reproduce

Backtrace