\[\frac{x.im \cdot y.re - x.re \cdot y.im}{y.re \cdot y.re + y.im \cdot y.im}\]

\frac{x.im \cdot y.re - x.re \cdot y.im}{y.re \cdot y.re + y.im \cdot y.im}

double f(double x_re, double x_im, double y_re, double y_im) {
        double r8286 = x_im;
        double r8287 = y_re;
        double r8288 = r8286 * r8287;
        double r8289 = x_re;
        double r8290 = y_im;
        double r8291 = r8289 * r8290;
        double r8292 = r8288 - r8291;
        double r8293 = r8287 * r8287;
        double r8294 = r8290 * r8290;
        double r8295 = r8293 + r8294;
        double r8296 = r8292 / r8295;
        return r8296;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019173 +o rules:numerics
(FPCore (x.re x.im y.re y.im)
  :name "_divideComplex, imaginary part"
  (/ (- (* x.im y.re) (* x.re y.im)) (+ (* y.re y.re) (* y.im y.im))))

Backtrace

atab-pick-alt: contract violation expected: alt? given: '(#<alt (λ (x.re x.im y.re y.im) (/ (fma (- y.im) x.re (* x.im y.re)) (fma y.im y.im (* y.re y.re))))>) in: the range of the #:picking-func argument of (-> alt-table? #:only-fresh boolean? #:picking-func (-> (listof alt?) alt?) (values alt? alt-table?)) contract from: /data/pavpan/nightlies/herbie/no-costs-2/src/core/alt-table.rkt blaming: /data/pavpan/nightlies/herbie/no-costs-2/src/mainloop.rkt (assuming the contract is correct) at: /data/pavpan/nightlies/herbie/no-costs-2/src/core/alt-table.rkt:13.3		L	C
raise-blame-error16	/opt/racket-7.0/collects/racket/contract/private/blame.rkt	347	0
(unnamed)	/data/pavpan/nightlies/herbie/no-costs-2/src/core/alt-table.rkt	59	0
(unnamed)	/opt/racket-7.0/collects/racket/contract/private/arrow-val-first.rkt	388	18
choose-best-alt!	/data/pavpan/nightlies/herbie/no-costs-2/src/mainloop.rkt	110	0
run-iter!	/data/pavpan/nightlies/herbie/no-costs-2/src/mainloop.rkt	319	0
for-loop	/data/pavpan/nightlies/herbie/no-costs-2/src/mainloop.rkt	353	4
run-improve43	/data/pavpan/nightlies/herbie/no-costs-2/src/mainloop.rkt	338	0
(unnamed)	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	261	28
run	/opt/racket-7.0/share/pkgs/profile-lib/main.rkt	39	2
profile-thunk16	/opt/racket-7.0/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/opt/racket-7.0/collects/racket/private/more-scheme.rkt	261	28