Outputs a sigmoid function.
1 − e 2 {\displaystyle {\sqrt {1-e^{2}}}}
f ( a i , x ) = x 1 [ x 4 e − 4 ln ( 2 ) ( a i − x 2 ) 2 x 3 2 + ( 1 − x 4 ) [ x 3 2 ( a i − x 2 ) 2 + x 3 2 ] ] {\displaystyle f\left({{a}_{i}},\mathbf {x} \right)={{x}_{1}}\left[{{x}_{4}}{{\operatorname {e} }^{\frac {-4\ln \left(2\right){{\left({{a}_{i}}-{{x}_{2}}\right)}^{2}}}{x_{3}^{2}}}}+\left(1-{{x}_{4}}\right)\left[{\frac {x_{3}^{2}}{{{\left({{a}_{i}}-{{x}_{2}}\right)}^{2}}+x_{3}^{2}}}\right]\right]}
f ( a i , x ) = x 1 [ + ( 1 − x 4 ) [ 1 − x 3 2 ( a i − x 2 ) 2 + x 3 2 ] ] {\displaystyle f\left({{a}_{i}},\mathbf {x} \right)={{x}_{1}}\left[{}+\left(1-{{x}_{4}}\right)\left[{\frac {1-x_{3}^{2}}{{{\left({{a}_{i}}-{{x}_{2}}\right)}^{2}}+x_{3}^{2}}}\right]\right]}
![{\displaystyle f\left({{a}_{i}},\mathbf {x} \right)={{x}_{1}}\left[{{x}_{4}}{{\operatorname {e} }^{\frac {-4\ln \left(2\right){{\left({{a}_{i}}-{{x}_{2}}\right)}^{2}}}{x_{3}^{2}}}}+\left(1-{{x}_{4}}\right)\left[{\frac {x_{3}^{2}}{{{\left({{a}_{i}}-{{x}_{2}}\right)}^{2}}+x_{3}^{2}}}\right]\right]}](https://wikimedia.org/api/rest_v1/media/math/render/svg/965a5fa73fcc814b61ed64985798616e4e0a5843)
![{\displaystyle f\left({{a}_{i}},\mathbf {x} \right)={{x}_{1}}\left[{}+\left(1-{{x}_{4}}\right)\left[{\frac {1-x_{3}^{2}}{{{\left({{a}_{i}}-{{x}_{2}}\right)}^{2}}+x_{3}^{2}}}\right]\right]}](https://wikimedia.org/api/rest_v1/media/math/render/svg/8644f1f4c5e45c6a8d7ce847f64693cb119690ab)
