\[\frac{\sqrt{2} \cdot t}{\sqrt{\frac{x + 1}{x - 1} \cdot \left(\ell \cdot \ell + 2 \cdot \left(t \cdot t\right)\right) - \ell \cdot \ell}}\]
\frac{\sqrt{2} \cdot t}{\sqrt{\frac{x + 1}{x - 1} \cdot \left(\ell \cdot \ell + 2 \cdot \left(t \cdot t\right)\right) - \ell \cdot \ell}}
(FPCore (x l t)
 :precision binary64
 (/
  (* (sqrt 2.0) t)
  (sqrt (- (* (/ (+ x 1.0) (- x 1.0)) (+ (* l l) (* 2.0 (* t t)))) (* l l)))))
double code(double x, double l, double t) {
	return (sqrt(2.0) * t) / sqrt((((x + 1.0) / (x - 1.0)) * ((l * l) + (2.0 * (t * t)))) - (l * l));
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2021060 
(FPCore (x l t)
  :name "Toniolo and Linder, Equation (7)"
  :precision binary64
  (/ (* (sqrt 2.0) t) (sqrt (- (* (/ (+ x 1.0) (- x 1.0)) (+ (* l l) (* 2.0 (* t t)))) (* l l)))))

Backtrace

Failed to produce proof for (/.f64 (*.f64 t t) 1) to (*.f64 t t)LC
for-loop/data/pavpan/nightlies/herbie/egg-generate-proof/src/core/simplify.rkt1678
(unnamed)/data/pavpan/nightlies/herbie/egg-generate-proof/src/core/simplify.rkt1496
egraph-add-exprs/data/pavpan/nightlies/herbie/egg-generate-proof/egg-herbie/main.rkt1540
with-egraph/data/pavpan/nightlies/herbie/egg-generate-proof/egg-herbie/main.rkt740
(unnamed)/data/pavpan/nightlies/herbie/egg-generate-proof/src/core/simplify.rkt790
simplify!/data/pavpan/nightlies/herbie/egg-generate-proof/src/mainloop.rkt2360
run-iter!/data/pavpan/nightlies/herbie/egg-generate-proof/src/mainloop.rkt3600
run-improve/data/pavpan/nightlies/herbie/egg-generate-proof/src/mainloop.rkt3770
(unnamed)/data/pavpan/nightlies/herbie/egg-generate-proof/src/sandbox.rkt546
run/opt/racket-7.9/share/pkgs/profile-lib/main.rkt392
profile-thunk/opt/racket-7.9/share/pkgs/profile-lib/main.rkt90
(unnamed)/opt/racket-7.9/collects/racket/engine.rkt4224