\[\left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right) \cdot \left(\frac{1}{a} - \frac{1}{b}\right)\]
\left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right) \cdot \left(\frac{1}{a} - \frac{1}{b}\right)
double f(double a, double b) {
        double r14608 = atan2(1.0, 0.0);
        double r14609 = 2.0;
        double r14610 = r14608 / r14609;
        double r14611 = 1.0;
        double r14612 = b;
        double r14613 = r14612 * r14612;
        double r14614 = a;
        double r14615 = r14614 * r14614;
        double r14616 = r14613 - r14615;
        double r14617 = r14611 / r14616;
        double r14618 = r14610 * r14617;
        double r14619 = r14611 / r14614;
        double r14620 = r14611 / r14612;
        double r14621 = r14619 - r14620;
        double r14622 = r14618 * r14621;
        return r14622;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019196 +o rules:numerics
(FPCore (a b)
  :name "NMSE Section 6.1 mentioned, B"
  (* (* (/ PI 2.0) (/ 1.0 (- (* b b) (* a a)))) (- (/ 1.0 a) (/ 1.0 b))))

Backtrace

get-representation: Unknown representation #fLC
(unnamed)/data/pavpan/nightlies/herbie/master/src/core/localize.rkt2313
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
map/opt/racket-7.0/collects/racket/private/map.rkt3513
parse-loop30/opt/racket-7.0/collects/racket/match/compiler.rkt41815
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
map/opt/racket-7.0/collects/racket/private/map.rkt3513
parse-loop30/opt/racket-7.0/collects/racket/match/compiler.rkt41815
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
map/opt/racket-7.0/collects/racket/private/map.rkt3513
parse-loop30/opt/racket-7.0/collects/racket/match/compiler.rkt41815
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
map/opt/racket-7.0/collects/racket/private/map.rkt3513
parse-loop30/opt/racket-7.0/collects/racket/match/compiler.rkt41815
hash-ref!/opt/racket-7.0/collects/racket/private/more-scheme.rkt3762
localize-error/data/pavpan/nightlies/herbie/master/src/core/localize.rkt610
localize!/data/pavpan/nightlies/herbie/master/src/mainloop.rkt1230
run-iter!/data/pavpan/nightlies/herbie/master/src/mainloop.rkt3230
for-loop/data/pavpan/nightlies/herbie/master/src/mainloop.rkt3594
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