\[R \cdot \sqrt{\left(\left(\lambda_1 - \lambda_2\right) \cdot \cos \left(\frac{\phi_1 + \phi_2}{2}\right)\right) \cdot \left(\left(\lambda_1 - \lambda_2\right) \cdot \cos \left(\frac{\phi_1 + \phi_2}{2}\right)\right) + \left(\phi_1 - \phi_2\right) \cdot \left(\phi_1 - \phi_2\right)}\]

R \cdot \sqrt{\left(\left(\lambda_1 - \lambda_2\right) \cdot \cos \left(\frac{\phi_1 + \phi_2}{2}\right)\right) \cdot \left(\left(\lambda_1 - \lambda_2\right) \cdot \cos \left(\frac{\phi_1 + \phi_2}{2}\right)\right) + \left(\phi_1 - \phi_2\right) \cdot \left(\phi_1 - \phi_2\right)}

double f(double R, double lambda1, double lambda2, double phi1, double phi2) {
        double r9620 = R;
        double r9621 = lambda1;
        double r9622 = lambda2;
        double r9623 = r9621 - r9622;
        double r9624 = phi1;
        double r9625 = phi2;
        double r9626 = r9624 + r9625;
        double r9627 = 2.0;
        double r9628 = r9626 / r9627;
        double r9629 = cos(r9628);
        double r9630 = r9623 * r9629;
        double r9631 = r9630 * r9630;
        double r9632 = r9624 - r9625;
        double r9633 = r9632 * r9632;
        double r9634 = r9631 + r9633;
        double r9635 = sqrt(r9634);
        double r9636 = r9620 * r9635;
        return r9636;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019315 
(FPCore (R lambda1 lambda2 phi1 phi2)
  :name "Equirectangular approximation to distance on a great circle"
  :precision binary64
  (* R (sqrt (+ (* (* (- lambda1 lambda2) (cos (/ (+ phi1 phi2) 2))) (* (- lambda1 lambda2) (cos (/ (+ phi1 phi2) 2)))) (* (- phi1 phi2) (- phi1 phi2))))))

Backtrace

match: no matching clause for 'binary64		L	C
match:error	/opt/racket-7.2/collects/racket/match/runtime.rkt	24	0
for-loop	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/reduce.rkt	246	3
make-multiplication-subnode	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/reduce.rkt	244	0
make-multiplication-node	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/reduce.rkt	234	0
parse-loop373	/opt/racket-7.2/collects/racket/match/compiler.rkt	418	15
parse-loop373	/opt/racket-7.2/collects/racket/match/compiler.rkt	418	15
append-map	/opt/racket-7.2/collects/racket/list.rkt	586	2
simplify-node	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/reduce.rkt	48	0
map	/opt/racket-7.2/collects/racket/private/map.rkt	35	13
f45	/opt/racket-7.2/collects/racket/match/compiler.rkt	507	40
simplify	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/reduce.rkt	16	0
approximate9	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/taylor.rkt	12	0
(unnamed)	/opt/racket-7.2/collects/racket/contract/private/arrow-higher-order.rkt	360	33
location-do	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/programs.rkt	64	0
location-do	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/programs.rkt	64	0
(unnamed)	/opt/racket-7.2/collects/racket/contract/private/arrow-higher-order.rkt	360	33
for-loop	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	151	6
taylor-alt	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	145	0
for-loop	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	166	7
gen-series!	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	159	0
run-iter!	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	326	0
for-loop	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	364	4
run-improve47	/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt	345	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