Error

Derivation

1. Split input into 3 regimes

2. if t < -1.2265457441387192e-21

   1. Initial program 40.6

      \[\frac{\sqrt{2} \cdot t}{\sqrt{\frac{x + 1}{x - 1} \cdot \left(\ell \cdot \ell + 2 \cdot \left(t \cdot t\right)\right) - \ell \cdot \ell}}\]

   2. Taylor expanded around -inf 5.9

      \[\leadsto \frac{\sqrt{2} \cdot t}{\color{blue}{2 \cdot \frac{t}{{\left(\sqrt{2}\right)}^{3} \cdot {x}^{2}} - \left(2 \cdot \frac{t}{\sqrt{2} \cdot {x}^{2}} + \left(t \cdot \sqrt{2} + 2 \cdot \frac{t}{\sqrt{2} \cdot x}\right)\right)}}\]

   3. Simplified5.9

      \[\leadsto \frac{\sqrt{2} \cdot t}{\color{blue}{\left(\frac{\frac{2}{x}}{x} \cdot \left(\frac{\frac{t}{\sqrt{2}}}{2} - \frac{t}{\sqrt{2}}\right) - \sqrt{2} \cdot t\right) + -2 \cdot \frac{\frac{t}{\sqrt{2}}}{x}}}\]

   if -1.2265457441387192e-21 < t < 4.340231136490074e+38

   1. Initial program 43.0

      \[\frac{\sqrt{2} \cdot t}{\sqrt{\frac{x + 1}{x - 1} \cdot \left(\ell \cdot \ell + 2 \cdot \left(t \cdot t\right)\right) - \ell \cdot \ell}}\]

   2. Taylor expanded around -inf 19.4

      \[\leadsto \frac{\sqrt{2} \cdot t}{\sqrt{\color{blue}{2 \cdot {t}^{2} + \left(2 \cdot \frac{{\ell}^{2}}{x} + 4 \cdot \frac{{t}^{2}}{x}\right)}}}\]

   3. Simplified15.9

      \[\leadsto \frac{\sqrt{2} \cdot t}{\sqrt{\color{blue}{\frac{\ell \cdot 2}{\frac{x}{\ell}} + t \cdot \left(t \cdot \left(2 + \frac{4}{x}\right)\right)}}}\]
   4. Using strategy rm

   5. Applied add-sqr-sqrt15.9

      \[\leadsto \frac{\color{blue}{\left(\sqrt{\sqrt{2}} \cdot \sqrt{\sqrt{2}}\right)} \cdot t}{\sqrt{\frac{\ell \cdot 2}{\frac{x}{\ell}} + t \cdot \left(t \cdot \left(2 + \frac{4}{x}\right)\right)}}\]

   6. Applied associate-*l*15.9

      \[\leadsto \frac{\color{blue}{\sqrt{\sqrt{2}} \cdot \left(\sqrt{\sqrt{2}} \cdot t\right)}}{\sqrt{\frac{\ell \cdot 2}{\frac{x}{\ell}} + t \cdot \left(t \cdot \left(2 + \frac{4}{x}\right)\right)}}\]

   if 4.340231136490074e+38 < t

   1. Initial program 42.8

      \[\frac{\sqrt{2} \cdot t}{\sqrt{\frac{x + 1}{x - 1} \cdot \left(\ell \cdot \ell + 2 \cdot \left(t \cdot t\right)\right) - \ell \cdot \ell}}\]

   2. Taylor expanded around inf 4.5

      \[\leadsto \frac{\sqrt{2} \cdot t}{\color{blue}{\left(2 \cdot \frac{t}{\sqrt{2} \cdot {x}^{2}} + \left(t \cdot \sqrt{2} + 2 \cdot \frac{t}{\sqrt{2} \cdot x}\right)\right) - 2 \cdot \frac{t}{{\left(\sqrt{2}\right)}^{3} \cdot {x}^{2}}}}\]

   3. Simplified4.5

      \[\leadsto \frac{\sqrt{2} \cdot t}{\color{blue}{\left(\sqrt{2} \cdot t + \frac{\frac{t}{\sqrt{2}} \cdot 2}{x}\right) + \left(\frac{\frac{t}{\sqrt{2}} \cdot 2}{x \cdot x} - \frac{\frac{t}{\sqrt{2}}}{x \cdot x}\right)}}\]
3. Recombined 3 regimes into one program.

4. Final simplification9.9

   \[\leadsto \begin{array}{l} \mathbf{if}\;t \le -1.2265457441387192 \cdot 10^{-21}:\\ \;\;\;\;\frac{\sqrt{2} \cdot t}{\left(\left(\frac{\frac{t}{\sqrt{2}}}{2} - \frac{t}{\sqrt{2}}\right) \cdot \frac{\frac{2}{x}}{x} - \sqrt{2} \cdot t\right) + \frac{\frac{t}{\sqrt{2}}}{x} \cdot -2}\\ \mathbf{elif}\;t \le 4.340231136490074 \cdot 10^{+38}:\\ \;\;\;\;\frac{\sqrt{\sqrt{2}} \cdot \left(\sqrt{\sqrt{2}} \cdot t\right)}{\sqrt{\left(t \cdot \left(2 + \frac{4}{x}\right)\right) \cdot t + \frac{\ell \cdot 2}{\frac{x}{\ell}}}}\\ \mathbf{else}:\\ \;\;\;\;\frac{\sqrt{2} \cdot t}{\left(\frac{2 \cdot \frac{t}{\sqrt{2}}}{x} + \sqrt{2} \cdot t\right) + \left(\frac{2 \cdot \frac{t}{\sqrt{2}}}{x \cdot x} - \frac{\frac{t}{\sqrt{2}}}{x \cdot x}\right)}\\ \end{array}\]

Reproduce

herbie shell --seed 2019051 
(FPCore (x l t)
  :name "Toniolo and Linder, Equation (7)"
  (/ (* (sqrt 2) t) (sqrt (- (* (/ (+ x 1) (- x 1)) (+ (* l l) (* 2 (* t t)))) (* l l)))))