Description
Invert softsign x/(1+abs(x)) as x=y/(1-abs(y)).
Softsign uses x/(1+abs(x)); its finite-input range is between -1 and 1. It has a first derivative at zero but different one-sided second derivatives there. Changing an additive denominator scale is distinct from multiplying the function’s input by a scale.
Invert softsign x/(1+abs(x)) as x=y/(1-abs(y)).
When to use this tool
Use Activation: Softsign Scalar Inverse when checking the stated softsign inverse, saturation or derivative convention.
How to use the tool and how it works
- Enter y. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read result. Expand result to inspect the returned fields.
Require abs(y)<1. Invert softsign x/(1+abs(x)) as x=y/(1-abs(y)).1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| y | Y | Required. Finite number. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| result | Object containing the operation-specific returned members listed below. | Required. Object. |
| result.x | Finite scalar input coordinate; use the mathematical scale specified above. | Calculated result member: number. |
{
"input": {
"y": 0.5
},
"output": {
"result": {
"x": 1
}
}
}Limitations and assumptions
- Output limits ±1 have no finite preimage; floating-point inversion near those limits can be very sensitive.
- Outputs are nested inside result. Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use the complete explicit function and the intended parameter, branch and numerical conventions for symbolic, tensor or model-level differentiation; assess training behavior independently.
References
Similar or alternative tools
- Softsign Scalar Second Derivative
For x!=0, return -2*sign(x)/(1+abs(x))³.
- Activation: Softsign Scalar Derivative
Return 1/(1+abs(x))² as the first scalar derivative of x/(1+abs(x)), including derivative one at zero.