\[\left(10^{-5} \leq x \land x \leq 1\right) \land \left(1 \leq tau \land tau \leq 5\right)\]

\[\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi} \]

(FPCore (x tau)
 :precision binary32
 (* (/ (sin (* (* x PI) tau)) (* (* x PI) tau)) (/ (sin (* x PI)) (* x PI))))

float code(float x, float tau) {
	return (sinf(((x * ((float) M_PI)) * tau)) / ((x * ((float) M_PI)) * tau)) * (sinf((x * ((float) M_PI))) / (x * ((float) M_PI)));
}

function code(x, tau)
	return Float32(Float32(sin(Float32(Float32(x * Float32(pi)) * tau)) / Float32(Float32(x * Float32(pi)) * tau)) * Float32(sin(Float32(x * Float32(pi))) / Float32(x * Float32(pi))))
end

function tmp = code(x, tau)
	tmp = (sin(((x * single(pi)) * tau)) / ((x * single(pi)) * tau)) * (sin((x * single(pi))) / (x * single(pi)));
end

\frac{\sin \left(\left(x \cdot \pi\right) \cdot tau\right)}{\left(x \cdot \pi\right) \cdot tau} \cdot \frac{\sin \left(x \cdot \pi\right)}{x \cdot \pi}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2022150 
(FPCore (x tau)
  :name "Lanczos kernel"
  :precision binary32
  :pre (and (and (<= 1e-5 x) (<= x 1.0)) (and (<= 1.0 tau) (<= tau 5.0)))
  (* (/ (sin (* (* x PI) tau)) (* (* x PI) tau)) (/ (sin (* x PI)) (* x PI))))

Backtrace

application: required keyword argument not supplied procedure: batch-egg-rewrite required keyword: #:rules arguments...: '(#<rule erfc-erf_binary32> #<rule erf-erfc_binary32> #<rule erf-odd_binary32> #<rule prod-diff_binary32> #<rule hypot-udef_binary32> #<rule expm1-log1p-u_binary32> #<rule log1p-expm1-u_binary32> #<rule log1p-udef_binary32> #<rule expm1-udef_binary32> #... #:depths '(1 1 1 1) #:roots '((2) (2) (2) (2))		L	C
(unnamed)	/opt/racket-8.1/collects/racket/private/kw.rkt	1558	14
rewrite-expressions	/data/pavpan/nightlies/herbie/timeline/src/core/matcher.rkt	171	0
gen-rewrites!	/data/pavpan/nightlies/herbie/timeline/src/patch.rkt	144	0
patch-table-run	/data/pavpan/nightlies/herbie/timeline/src/patch.rkt	291	0
(unnamed)	/opt/racket-8.1/collects/racket/contract/private/arrow-val-first.rkt	486	18
run-iter!	/data/pavpan/nightlies/herbie/timeline/src/mainloop.rkt	246	0
mutate!	/data/pavpan/nightlies/herbie/timeline/src/mainloop.rkt	379	0
run-improve!	/data/pavpan/nightlies/herbie/timeline/src/mainloop.rkt	326	0
(unnamed)	/data/pavpan/nightlies/herbie/timeline/src/sandbox.rkt	66	6
(unnamed)	/opt/racket-8.1/share/pkgs/profile-lib/main.rkt	40	10
profile-thunk	/opt/racket-8.1/share/pkgs/profile-lib/main.rkt	9	0
(unnamed)	/opt/racket-8.1/collects/racket/engine.rkt	42	24