Average Error: 14.0 → 14.0
Time: 7.4s
Precision: binary64
\[1 - \left(\frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(0.25482959199999999 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-0.284496735999999972 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(1.42141374100000006 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-1.45315202700000001 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot 1.0614054289999999\right)\right)\right)\right)\right) \cdot e^{-\left|x\right| \cdot \left|x\right|}\]
\[1 - \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \frac{\sqrt[3]{{\left(0.25482959199999999 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-0.284496735999999972 + 1 \cdot \frac{1.42141374100000006 + \left(\frac{1.0614054289999999}{{\left(1 + 0.32759110000000002 \cdot \left|x\right|\right)}^{2}} - \frac{1.45315202700000001}{1 + 0.32759110000000002 \cdot \left|x\right|}\right)}{1 + 0.32759110000000002 \cdot \left|x\right|}\right)\right)}^{3}}}{{\left(e^{\left|x\right|}\right)}^{\left(\left|x\right|\right)}}\]

Error

Bits error versus x

Derivation

  1. Initial program 14.0

    \[1 - \left(\frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(0.25482959199999999 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-0.284496735999999972 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(1.42141374100000006 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-1.45315202700000001 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot 1.0614054289999999\right)\right)\right)\right)\right) \cdot e^{-\left|x\right| \cdot \left|x\right|}\]
  2. Simplified14.0

    \[\leadsto \color{blue}{1 - \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \frac{0.25482959199999999 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-0.284496735999999972 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(1.42141374100000006 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-1.45315202700000001 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot 1.0614054289999999\right)\right)\right)}{{\left(e^{\left|x\right|}\right)}^{\left(\left|x\right|\right)}}}\]
  3. Taylor expanded around 0 14.0

    \[\leadsto 1 - \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \frac{0.25482959199999999 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-0.284496735999999972 + \color{blue}{1 \cdot \frac{\left(1.0614054289999999 \cdot \frac{1}{{\left(0.32759110000000002 \cdot \left|x\right| + 1\right)}^{2}} + 1.42141374100000006\right) - 1.45315202700000001 \cdot \frac{1}{0.32759110000000002 \cdot \left|x\right| + 1}}{0.32759110000000002 \cdot \left|x\right| + 1}}\right)}{{\left(e^{\left|x\right|}\right)}^{\left(\left|x\right|\right)}}\]
  4. Simplified14.0

    \[\leadsto 1 - \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \frac{0.25482959199999999 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-0.284496735999999972 + \color{blue}{1 \cdot \frac{1.42141374100000006 + \left(\frac{1.0614054289999999}{{\left(1 + 0.32759110000000002 \cdot \left|x\right|\right)}^{2}} - \frac{1.45315202700000001}{1 + 0.32759110000000002 \cdot \left|x\right|}\right)}{1 + 0.32759110000000002 \cdot \left|x\right|}}\right)}{{\left(e^{\left|x\right|}\right)}^{\left(\left|x\right|\right)}}\]
  5. Using strategy rm
  6. Applied add-cbrt-cube14.0

    \[\leadsto 1 - \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \frac{\color{blue}{\sqrt[3]{\left(\left(0.25482959199999999 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-0.284496735999999972 + 1 \cdot \frac{1.42141374100000006 + \left(\frac{1.0614054289999999}{{\left(1 + 0.32759110000000002 \cdot \left|x\right|\right)}^{2}} - \frac{1.45315202700000001}{1 + 0.32759110000000002 \cdot \left|x\right|}\right)}{1 + 0.32759110000000002 \cdot \left|x\right|}\right)\right) \cdot \left(0.25482959199999999 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-0.284496735999999972 + 1 \cdot \frac{1.42141374100000006 + \left(\frac{1.0614054289999999}{{\left(1 + 0.32759110000000002 \cdot \left|x\right|\right)}^{2}} - \frac{1.45315202700000001}{1 + 0.32759110000000002 \cdot \left|x\right|}\right)}{1 + 0.32759110000000002 \cdot \left|x\right|}\right)\right)\right) \cdot \left(0.25482959199999999 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-0.284496735999999972 + 1 \cdot \frac{1.42141374100000006 + \left(\frac{1.0614054289999999}{{\left(1 + 0.32759110000000002 \cdot \left|x\right|\right)}^{2}} - \frac{1.45315202700000001}{1 + 0.32759110000000002 \cdot \left|x\right|}\right)}{1 + 0.32759110000000002 \cdot \left|x\right|}\right)\right)}}}{{\left(e^{\left|x\right|}\right)}^{\left(\left|x\right|\right)}}\]
  7. Simplified14.0

    \[\leadsto 1 - \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \frac{\sqrt[3]{\color{blue}{{\left(0.25482959199999999 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-0.284496735999999972 + 1 \cdot \frac{1.42141374100000006 + \left(\frac{1.0614054289999999}{{\left(1 + 0.32759110000000002 \cdot \left|x\right|\right)}^{2}} - \frac{1.45315202700000001}{1 + 0.32759110000000002 \cdot \left|x\right|}\right)}{1 + 0.32759110000000002 \cdot \left|x\right|}\right)\right)}^{3}}}}{{\left(e^{\left|x\right|}\right)}^{\left(\left|x\right|\right)}}\]
  8. Final simplification14.0

    \[\leadsto 1 - \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \frac{\sqrt[3]{{\left(0.25482959199999999 + \frac{1}{1 + 0.32759110000000002 \cdot \left|x\right|} \cdot \left(-0.284496735999999972 + 1 \cdot \frac{1.42141374100000006 + \left(\frac{1.0614054289999999}{{\left(1 + 0.32759110000000002 \cdot \left|x\right|\right)}^{2}} - \frac{1.45315202700000001}{1 + 0.32759110000000002 \cdot \left|x\right|}\right)}{1 + 0.32759110000000002 \cdot \left|x\right|}\right)\right)}^{3}}}{{\left(e^{\left|x\right|}\right)}^{\left(\left|x\right|\right)}}\]

Reproduce

herbie shell --seed 2020185 
(FPCore (x)
  :name "Jmat.Real.erf"
  :precision binary64
  (- 1.0 (* (* (/ 1.0 (+ 1.0 (* 0.3275911 (fabs x)))) (+ 0.254829592 (* (/ 1.0 (+ 1.0 (* 0.3275911 (fabs x)))) (+ -0.284496736 (* (/ 1.0 (+ 1.0 (* 0.3275911 (fabs x)))) (+ 1.421413741 (* (/ 1.0 (+ 1.0 (* 0.3275911 (fabs x)))) (+ -1.453152027 (* (/ 1.0 (+ 1.0 (* 0.3275911 (fabs x)))) 1.061405429))))))))) (exp (neg (* (fabs x) (fabs x)))))))