\[\left|\frac{1}{\sqrt{\pi}} \cdot \left(\left(\left(2 \cdot \left|x\right| + \frac{2}{3} \cdot \left(\left(\left|x\right| \cdot \left|x\right|\right) \cdot \left|x\right|\right)\right) + \frac{1}{5} \cdot \left(\left(\left(\left(\left|x\right| \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right)\right) + \frac{1}{21} \cdot \left(\left(\left(\left(\left(\left(\left|x\right| \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right)\right)\right|\]
Test:
Jmat.Real.erfi, branch x less than or equal to 0.5
Bits:
128 bits
Bits error versus x
Time: 16.8 s
Input Error: 0.3
Output Error: 0.4
Log: ⚲
Profile: 🕒
\(\left|\frac{(\left(\frac{\left|x\right|}{5} \cdot {\left(\left|x\right|\right)}^3\right) * \left(\left|x\right|\right) + \left((\left(\frac{2}{3}\right) * \left({\left(\left|x\right|\right)}^3\right) + \left(2 \cdot \left|x\right|\right))_*\right))_* + \frac{{\left(\left|{\left(\left|x\right|\right)}^3\right|\right)}^2}{\frac{21}{\left|x\right|}}}{\sqrt{\pi}}\right|\)
  1. Started with
    \[\left|\frac{1}{\sqrt{\pi}} \cdot \left(\left(\left(2 \cdot \left|x\right| + \frac{2}{3} \cdot \left(\left(\left|x\right| \cdot \left|x\right|\right) \cdot \left|x\right|\right)\right) + \frac{1}{5} \cdot \left(\left(\left(\left(\left|x\right| \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right)\right) + \frac{1}{21} \cdot \left(\left(\left(\left(\left(\left(\left|x\right| \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right)\right)\right|\]
    0.3
  2. Applied simplify to get
    \[\color{red}{\left|\frac{1}{\sqrt{\pi}} \cdot \left(\left(\left(2 \cdot \left|x\right| + \frac{2}{3} \cdot \left(\left(\left|x\right| \cdot \left|x\right|\right) \cdot \left|x\right|\right)\right) + \frac{1}{5} \cdot \left(\left(\left(\left(\left|x\right| \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right)\right) + \frac{1}{21} \cdot \left(\left(\left(\left(\left(\left(\left|x\right| \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right) \cdot \left|x\right|\right)\right)\right|} \leadsto \color{blue}{\left|\frac{(\left(\frac{\left|x\right|}{5} \cdot {\left(\left|x\right|\right)}^3\right) * \left(\left|x\right|\right) + \left((\left(\frac{2}{3}\right) * \left({\left(\left|x\right|\right)}^3\right) + \left(2 \cdot \left|x\right|\right))_*\right))_* + \frac{{\left({\left(\left|x\right|\right)}^2\right)}^3}{\frac{21}{\left|x\right|}}}{\sqrt{\pi}}\right|}\]
    0.4
  3. Using strategy rm
    0.4
  4. Applied add-sqr-sqrt to get
    \[\left|\frac{(\left(\frac{\left|x\right|}{5} \cdot {\left(\left|x\right|\right)}^3\right) * \left(\left|x\right|\right) + \left((\left(\frac{2}{3}\right) * \left({\left(\left|x\right|\right)}^3\right) + \left(2 \cdot \left|x\right|\right))_*\right))_* + \frac{\color{red}{{\left({\left(\left|x\right|\right)}^2\right)}^3}}{\frac{21}{\left|x\right|}}}{\sqrt{\pi}}\right| \leadsto \left|\frac{(\left(\frac{\left|x\right|}{5} \cdot {\left(\left|x\right|\right)}^3\right) * \left(\left|x\right|\right) + \left((\left(\frac{2}{3}\right) * \left({\left(\left|x\right|\right)}^3\right) + \left(2 \cdot \left|x\right|\right))_*\right))_* + \frac{\color{blue}{{\left(\sqrt{{\left({\left(\left|x\right|\right)}^2\right)}^3}\right)}^2}}{\frac{21}{\left|x\right|}}}{\sqrt{\pi}}\right|\]
    0.4
  5. Applied simplify to get
    \[\left|\frac{(\left(\frac{\left|x\right|}{5} \cdot {\left(\left|x\right|\right)}^3\right) * \left(\left|x\right|\right) + \left((\left(\frac{2}{3}\right) * \left({\left(\left|x\right|\right)}^3\right) + \left(2 \cdot \left|x\right|\right))_*\right))_* + \frac{{\color{red}{\left(\sqrt{{\left({\left(\left|x\right|\right)}^2\right)}^3}\right)}}^2}{\frac{21}{\left|x\right|}}}{\sqrt{\pi}}\right| \leadsto \left|\frac{(\left(\frac{\left|x\right|}{5} \cdot {\left(\left|x\right|\right)}^3\right) * \left(\left|x\right|\right) + \left((\left(\frac{2}{3}\right) * \left({\left(\left|x\right|\right)}^3\right) + \left(2 \cdot \left|x\right|\right))_*\right))_* + \frac{{\color{blue}{\left(\left|{\left(\left|x\right|\right)}^3\right|\right)}}^2}{\frac{21}{\left|x\right|}}}{\sqrt{\pi}}\right|\]
    0.4
  6. Removed slow pow expressions

Original test:


(lambda ((x default))
  #:name "Jmat.Real.erfi, branch x less than or equal to 0.5"
  (fabs (* (/ 1 (sqrt PI)) (+ (+ (+ (* 2 (fabs x)) (* (/ 2 3) (* (* (fabs x) (fabs x)) (fabs x)))) (* (/ 1 5) (* (* (* (* (fabs x) (fabs x)) (fabs x)) (fabs x)) (fabs x)))) (* (/ 1 21) (* (* (* (* (* (* (fabs x) (fabs x)) (fabs x)) (fabs x)) (fabs x)) (fabs x)) (fabs x)))))))