Average Error: 1.7 → 1.7
Time: 12.8s
Precision: 64
Internal Precision: 320
\[\frac{\left(-b_2\right) + \sqrt{b_2 \cdot b_2 - a \cdot c}}{a}\]
\[\frac{\sqrt{\frac{b_2 \cdot b_2 + c \cdot a}{\frac{b_2 \cdot b_2 + c \cdot a}{b_2 \cdot b_2 - c \cdot a}}} - b_2}{a}\]

Error

Bits error versus a

Bits error versus b_2

Bits error versus c

Derivation

  1. Initial program 1.7

    \[\frac{\left(\frac{\left(-b_2\right)}{\left(\sqrt{\left(\left(b_2 \cdot b_2\right) - \left(a \cdot c\right)\right)}\right)}\right)}{a}\]
  2. Simplified1.7

    \[\leadsto \color{blue}{\frac{\left(\left(\sqrt{\left(\left(b_2 \cdot b_2\right) - \left(c \cdot a\right)\right)}\right) - b_2\right)}{a}}\]
  3. Using strategy rm
  4. Applied p16-flip--2.7

    \[\leadsto \frac{\left(\left(\sqrt{\color{blue}{\left(\frac{\left(\left(\left(b_2 \cdot b_2\right) \cdot \left(b_2 \cdot b_2\right)\right) - \left(\left(c \cdot a\right) \cdot \left(c \cdot a\right)\right)\right)}{\left(\frac{\left(b_2 \cdot b_2\right)}{\left(c \cdot a\right)}\right)}\right)}}\right) - b_2\right)}{a}\]
  5. Using strategy rm
  6. Applied difference-of-squares2.6

    \[\leadsto \frac{\left(\left(\sqrt{\left(\frac{\color{blue}{\left(\left(\frac{\left(b_2 \cdot b_2\right)}{\left(c \cdot a\right)}\right) \cdot \left(\left(b_2 \cdot b_2\right) - \left(c \cdot a\right)\right)\right)}}{\left(\frac{\left(b_2 \cdot b_2\right)}{\left(c \cdot a\right)}\right)}\right)}\right) - b_2\right)}{a}\]
  7. Applied associate-/l*1.7

    \[\leadsto \frac{\left(\left(\sqrt{\color{blue}{\left(\frac{\left(\frac{\left(b_2 \cdot b_2\right)}{\left(c \cdot a\right)}\right)}{\left(\frac{\left(\frac{\left(b_2 \cdot b_2\right)}{\left(c \cdot a\right)}\right)}{\left(\left(b_2 \cdot b_2\right) - \left(c \cdot a\right)\right)}\right)}\right)}}\right) - b_2\right)}{a}\]
  8. Final simplification1.7

    \[\leadsto \frac{\sqrt{\frac{b_2 \cdot b_2 + c \cdot a}{\frac{b_2 \cdot b_2 + c \cdot a}{b_2 \cdot b_2 - c \cdot a}}} - b_2}{a}\]

Reproduce

herbie shell --seed 2019093 
(FPCore (a b_2 c)
  :name "quad2p (problem 3.2.1, positive)"
  (/.p16 (+.p16 (neg.p16 b_2) (sqrt.p16 (-.p16 (*.p16 b_2 b_2) (*.p16 a c)))) a))