\[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}\]
Test:
NMSE problem 3.3.3
Bits:
128 bits
Bits error versus x
Time: 6.4 s
Input Error: 4.0
Output Error: 0.1
Log:
Profile: 🕒
\(\frac{\frac{2}{x}}{\left(x - 1\right) \cdot \left(1 + x\right)}\)
  1. Started with
    \[\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}\]
    4.0
  2. Using strategy rm
    4.0
  3. Applied add-cube-cbrt to get
    \[\color{red}{\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}} \leadsto \color{blue}{{\left(\sqrt[3]{\left(\frac{1}{x + 1} - \frac{2}{x}\right) + \frac{1}{x - 1}}\right)}^3}\]
    4.3
  4. Using strategy rm
    4.3
  5. Applied frac-sub to get
    \[{\left(\sqrt[3]{\color{red}{\left(\frac{1}{x + 1} - \frac{2}{x}\right)} + \frac{1}{x - 1}}\right)}^3 \leadsto {\left(\sqrt[3]{\color{blue}{\frac{1 \cdot x - \left(x + 1\right) \cdot 2}{\left(x + 1\right) \cdot x}} + \frac{1}{x - 1}}\right)}^3\]
    11.6
  6. Applied frac-add to get
    \[{\left(\sqrt[3]{\color{red}{\frac{1 \cdot x - \left(x + 1\right) \cdot 2}{\left(x + 1\right) \cdot x} + \frac{1}{x - 1}}}\right)}^3 \leadsto {\left(\sqrt[3]{\color{blue}{\frac{\left(1 \cdot x - \left(x + 1\right) \cdot 2\right) \cdot \left(x - 1\right) + \left(\left(x + 1\right) \cdot x\right) \cdot 1}{\left(\left(x + 1\right) \cdot x\right) \cdot \left(x - 1\right)}}}\right)}^3\]
    11.5
  7. Applied cbrt-div to get
    \[{\color{red}{\left(\sqrt[3]{\frac{\left(1 \cdot x - \left(x + 1\right) \cdot 2\right) \cdot \left(x - 1\right) + \left(\left(x + 1\right) \cdot x\right) \cdot 1}{\left(\left(x + 1\right) \cdot x\right) \cdot \left(x - 1\right)}}\right)}}^3 \leadsto {\color{blue}{\left(\frac{\sqrt[3]{\left(1 \cdot x - \left(x + 1\right) \cdot 2\right) \cdot \left(x - 1\right) + \left(\left(x + 1\right) \cdot x\right) \cdot 1}}{\sqrt[3]{\left(\left(x + 1\right) \cdot x\right) \cdot \left(x - 1\right)}}\right)}}^3\]
    11.6
  8. Applied cube-div to get
    \[\color{red}{{\left(\frac{\sqrt[3]{\left(1 \cdot x - \left(x + 1\right) \cdot 2\right) \cdot \left(x - 1\right) + \left(\left(x + 1\right) \cdot x\right) \cdot 1}}{\sqrt[3]{\left(\left(x + 1\right) \cdot x\right) \cdot \left(x - 1\right)}}\right)}^3} \leadsto \color{blue}{\frac{{\left(\sqrt[3]{\left(1 \cdot x - \left(x + 1\right) \cdot 2\right) \cdot \left(x - 1\right) + \left(\left(x + 1\right) \cdot x\right) \cdot 1}\right)}^3}{{\left(\sqrt[3]{\left(\left(x + 1\right) \cdot x\right) \cdot \left(x - 1\right)}\right)}^3}}\]
    11.6
  9. Applied simplify to get
    \[\frac{\color{red}{{\left(\sqrt[3]{\left(1 \cdot x - \left(x + 1\right) \cdot 2\right) \cdot \left(x - 1\right) + \left(\left(x + 1\right) \cdot x\right) \cdot 1}\right)}^3}}{{\left(\sqrt[3]{\left(\left(x + 1\right) \cdot x\right) \cdot \left(x - 1\right)}\right)}^3} \leadsto \frac{\color{blue}{\left(x + x \cdot x\right) + \left(\left(x - 2\right) - x \cdot 2\right) \cdot \left(x - 1\right)}}{{\left(\sqrt[3]{\left(\left(x + 1\right) \cdot x\right) \cdot \left(x - 1\right)}\right)}^3}\]
    11.6
  10. Applied simplify to get
    \[\frac{\left(x + x \cdot x\right) + \left(\left(x - 2\right) - x \cdot 2\right) \cdot \left(x - 1\right)}{\color{red}{{\left(\sqrt[3]{\left(\left(x + 1\right) \cdot x\right) \cdot \left(x - 1\right)}\right)}^3}} \leadsto \frac{\left(x + x \cdot x\right) + \left(\left(x - 2\right) - x \cdot 2\right) \cdot \left(x - 1\right)}{\color{blue}{x \cdot \left(\left(x + 1\right) \cdot \left(x - 1\right)\right)}}\]
    11.3
  11. Applied taylor to get
    \[\frac{\left(x + x \cdot x\right) + \left(\left(x - 2\right) - x \cdot 2\right) \cdot \left(x - 1\right)}{x \cdot \left(\left(x + 1\right) \cdot \left(x - 1\right)\right)} \leadsto \frac{2}{x \cdot \left(\left(x + 1\right) \cdot \left(x - 1\right)\right)}\]
    0.4
  12. Taylor expanded around 0 to get
    \[\frac{\color{red}{2}}{x \cdot \left(\left(x + 1\right) \cdot \left(x - 1\right)\right)} \leadsto \frac{\color{blue}{2}}{x \cdot \left(\left(x + 1\right) \cdot \left(x - 1\right)\right)}\]
    0.4
  13. Applied simplify to get
    \[\frac{2}{x \cdot \left(\left(x + 1\right) \cdot \left(x - 1\right)\right)} \leadsto \frac{\frac{2}{x}}{\left(x - 1\right) \cdot \left(1 + x\right)}\]
    0.1

  14. Applied final simplification

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))))