Average Error: 1.6 → 0.4
Time: 15.2s
Precision: 64
Internal Precision: 320
\[\sqrt{x + 1} - \sqrt{x}\]
\[\frac{1 + \left(x - x\right)}{\sqrt{x + 1} + \sqrt{x}}\]

Error

Bits error versus x

Derivation

  1. Initial program 1.6

    \[\left(\sqrt{\left(\frac{x}{\left(real->posit(1)\right)}\right)}\right) - \left(\sqrt{x}\right)\]
  2. Using strategy rm
  3. Applied p16-flip--1.2

    \[\leadsto \color{blue}{\frac{\left(\left(\left(\sqrt{\left(\frac{x}{\left(real->posit(1)\right)}\right)}\right) \cdot \left(\sqrt{\left(\frac{x}{\left(real->posit(1)\right)}\right)}\right)\right) - \left(\left(\sqrt{x}\right) \cdot \left(\sqrt{x}\right)\right)\right)}{\left(\frac{\left(\sqrt{\left(\frac{x}{\left(real->posit(1)\right)}\right)}\right)}{\left(\sqrt{x}\right)}\right)}}\]
  4. Using strategy rm
  5. Applied sqrt-sqrd.p160.9

    \[\leadsto \frac{\left(\color{blue}{\left(\frac{x}{\left(real->posit(1)\right)}\right)} - \left(\left(\sqrt{x}\right) \cdot \left(\sqrt{x}\right)\right)\right)}{\left(\frac{\left(\sqrt{\left(\frac{x}{\left(real->posit(1)\right)}\right)}\right)}{\left(\sqrt{x}\right)}\right)}\]
  6. Using strategy rm
  7. Applied +-commutative0.9

    \[\leadsto \frac{\left(\color{blue}{\left(\frac{\left(real->posit(1)\right)}{x}\right)} - \left(\left(\sqrt{x}\right) \cdot \left(\sqrt{x}\right)\right)\right)}{\left(\frac{\left(\sqrt{\left(\frac{x}{\left(real->posit(1)\right)}\right)}\right)}{\left(\sqrt{x}\right)}\right)}\]
  8. Applied associate--l+0.6

    \[\leadsto \frac{\color{blue}{\left(\frac{\left(real->posit(1)\right)}{\left(x - \left(\left(\sqrt{x}\right) \cdot \left(\sqrt{x}\right)\right)\right)}\right)}}{\left(\frac{\left(\sqrt{\left(\frac{x}{\left(real->posit(1)\right)}\right)}\right)}{\left(\sqrt{x}\right)}\right)}\]
  9. Using strategy rm
  10. Applied sqrt-sqrd.p160.4

    \[\leadsto \frac{\left(\frac{\left(real->posit(1)\right)}{\left(x - \color{blue}{x}\right)}\right)}{\left(\frac{\left(\sqrt{\left(\frac{x}{\left(real->posit(1)\right)}\right)}\right)}{\left(\sqrt{x}\right)}\right)}\]
  11. Final simplification0.4

    \[\leadsto \frac{1 + \left(x - x\right)}{\sqrt{x + 1} + \sqrt{x}}\]

Reproduce

herbie shell --seed 2019072 
(FPCore (x)
  :name "2sqrt (example 3.1)"
  (-.p16 (sqrt.p16 (+.p16 x (real->posit16 1))) (sqrt.p16 x)))