\[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}\]
Test:
NMSE problem 3.3.3
Bits:
128 bits
Bits error versus x
Time: 21.7 s
Input Error: 4.1
Output Error: 0.4
Log:
Profile: 🕒
\(\begin{cases} \left(\frac{2}{{x}^{5}} + \frac{2}{{x}^{7}}\right) + \frac{2}{{x}^3} & \text{when } x \le -2.3631973f0 \\ \left(\left(\frac{1}{x - 1} + \frac{1}{1 + x}\right) - \frac{2}{x}\right) \cdot 1 & \text{when } x \le 9.955491f0 \\ \left(\frac{2}{{x}^{5}} + \frac{2}{{x}^{7}}\right) + \frac{2}{{x}^3} & \text{otherwise} \end{cases}\)

    if x < -2.3631973f0 or 9.955491f0 < x

    1. Started with
      \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}\]
      8.4
    2. Applied taylor to get
      \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1} \leadsto 2 \cdot \frac{1}{{x}^{5}} + \left(2 \cdot \frac{1}{{x}^{7}} + 2 \cdot \frac{1}{{x}^{3}}\right)\]
      0.8
    3. Taylor expanded around inf to get
      \[\color{red}{2 \cdot \frac{1}{{x}^{5}} + \left(2 \cdot \frac{1}{{x}^{7}} + 2 \cdot \frac{1}{{x}^{3}}\right)} \leadsto \color{blue}{2 \cdot \frac{1}{{x}^{5}} + \left(2 \cdot \frac{1}{{x}^{7}} + 2 \cdot \frac{1}{{x}^{3}}\right)}\]
      0.8
    4. Applied simplify to get
      \[\color{red}{2 \cdot \frac{1}{{x}^{5}} + \left(2 \cdot \frac{1}{{x}^{7}} + 2 \cdot \frac{1}{{x}^{3}}\right)} \leadsto \color{blue}{\left(\frac{2}{{x}^{5}} + \frac{2}{{x}^{7}}\right) + \frac{2}{{x}^3}}\]
      0.8

    if -2.3631973f0 < x < 9.955491f0

    1. Started with
      \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}\]
      0.1
    2. Using strategy rm
      0.1
    3. Applied flip-+ to get
      \[\color{red}{\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}} \leadsto \color{blue}{\frac{{\left(\frac{1}{x + 1} - \frac{2}{x}\right)}^2 - {\left(\frac{1}{x - 1}\right)}^2}{\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}}}\]
      13.8
    4. Using strategy rm
      13.8
    5. Applied *-un-lft-identity to get
      \[\frac{{\left(\frac{1}{x + 1} - \frac{2}{x}\right)}^2 - {\left(\frac{1}{x - 1}\right)}^2}{\color{red}{\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}}} \leadsto \frac{{\left(\frac{1}{x + 1} - \frac{2}{x}\right)}^2 - {\left(\frac{1}{x - 1}\right)}^2}{\color{blue}{1 \cdot \left(\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}\right)}}\]
      13.8
    6. Applied difference-of-squares to get
      \[\frac{\color{red}{{\left(\frac{1}{x + 1} - \frac{2}{x}\right)}^2 - {\left(\frac{1}{x - 1}\right)}^2}}{1 \cdot \left(\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}\right)} \leadsto \frac{\color{blue}{\left(\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}\right) \cdot \left(\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}\right)}}{1 \cdot \left(\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}\right)}\]
      13.8
    7. Applied times-frac to get
      \[\color{red}{\frac{\left(\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}\right) \cdot \left(\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}\right)}{1 \cdot \left(\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}\right)}} \leadsto \color{blue}{\frac{\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}}{1} \cdot \frac{\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}}{\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}}}\]
      0.1
    8. Applied simplify to get
      \[\color{red}{\frac{\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}}{1}} \cdot \frac{\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}}{\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}} \leadsto \color{blue}{\left(\left(\frac{1}{x - 1} + \frac{1}{1 + x}\right) - \frac{2}{x}\right)} \cdot \frac{\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}}{\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}}\]
      0.1
    9. Applied simplify to get
      \[\left(\left(\frac{1}{x - 1} + \frac{1}{1 + x}\right) - \frac{2}{x}\right) \cdot \color{red}{\frac{\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}}{\left(\frac{1}{x + 1} - \frac{2}{x}\right) - \frac{1}{x - 1}}} \leadsto \left(\left(\frac{1}{x - 1} + \frac{1}{1 + x}\right) - \frac{2}{x}\right) \cdot \color{blue}{1}\]
      0.1

  1. Removed slow pow expressions

Original test:


(lambda ((x default))
  #:name "NMSE problem 3.3.3"
  (+ (- (/ 1 (+ x 1)) (/ 2 x)) (/ 1 (- x 1)))
  #:target
  (/ 2 (* x (- (sqr x) 1))))