\[\frac{\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}}{a}\]
Test:
NMSE problem 3.2.1, negative
Bits:
128 bits
Bits error versus a
Bits error versus b/2
Bits error versus c
Time: 11.1 s
Input Error: 33.5
Output Error: 32.6
Log: ⚲
Profile: 🕒
\(\frac{\frac{a}{1} \cdot \frac{c}{\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}}}{a}\)
  1. Started with
    \[\frac{\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}}{a}\]
    33.5
  2. Using strategy rm
    33.5
  3. Applied flip-- to get
    \[\frac{\color{red}{\left(-b/2\right) - \sqrt{{b/2}^2 - a \cdot c}}}{a} \leadsto \frac{\color{blue}{\frac{{\left(-b/2\right)}^2 - {\left(\sqrt{{b/2}^2 - a \cdot c}\right)}^2}{\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}}}}{a}\]
    44.0
  4. Applied simplify to get
    \[\frac{\frac{\color{red}{{\left(-b/2\right)}^2 - {\left(\sqrt{{b/2}^2 - a \cdot c}\right)}^2}}{\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}}}{a} \leadsto \frac{\frac{\color{blue}{a \cdot c}}{\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}}}{a}\]
    33.4
  5. Using strategy rm
    33.4
  6. Applied *-un-lft-identity to get
    \[\frac{\frac{a \cdot c}{\color{red}{\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}}}}{a} \leadsto \frac{\frac{a \cdot c}{\color{blue}{1 \cdot \left(\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}\right)}}}{a}\]
    33.4
  7. Applied times-frac to get
    \[\frac{\color{red}{\frac{a \cdot c}{1 \cdot \left(\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}\right)}}}{a} \leadsto \frac{\color{blue}{\frac{a}{1} \cdot \frac{c}{\left(-b/2\right) + \sqrt{{b/2}^2 - a \cdot c}}}}{a}\]
    32.6

Original test:


(lambda ((a default) (b/2 default) (c default))
  #:name "NMSE problem 3.2.1, negative"
  (/ (- (- b/2) (sqrt (- (sqr b/2) (* a c)))) a))