| Ref. | Name | Expression | Notes |
| [14, 15] | Step-like | | | Linear | | | Saturated linear | | Where to ensure continuity is α | Sigmoid | | | Hyp. tangent | | |
| [16] | Arctangent | | |
| [18] | Quadratic sigmoid function | | |
| [19, 22] | Logarithmic-Exponential | | is responsible for centering the function, distances the sigmoid, and is a coefficient that controls the slope |
| [19] | Triangular approximation | | Where , , , , , and are −0.54324, −0.16957, 1, 0.42654, 1.52, and 2.57, respectively. and are 0.016 and 0.4519, respectively |
| [21] | Hermite polyn. | , where , , with
| |
| [22] | Gaussian | | |
| [26] | PolyExp | | Where , , and are tunable constants |
| [24, 26] | Wave | | |
| [22, 23] | Neural | | Where controls the slope while governs the frequency of the resultant function |
| [23] | Sinusoidal | | Where is a parameter related to the frequency of the sine function |
| [25] | CosGauss | | The parameter in the function scales the gradient of the Gaussian function; meanwhile controls the frequency of repetition of the “hills” |
| [26] | Sinc | | |
| [26] | SinCos | | Where and are frequencies and and are proportional parameters |
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