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Gaussian Activation Width Sensitivity Tool

Differentiate exp(-(x/width)²) with respect to positive width.

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Description

Let z=x/width; return 2*z²*exp(-z²)/width as the width partial derivative, or zero when z is nonfinite or abs(z)>40.

A Gaussian-shaped activation exp(-(x/width)²) depends on the dimensionless ratio of input to positive width. Sensitivity to width is distinct from the input derivative; increasing width changes the spread rather than translating the activation.

Let z=x/width; return 2*z²*exp(-z²)/width as the width partial derivative, or zero when z is nonfinite or abs(z)>40.

When to use this tool

Use Gaussian Activation Width Sensitivity when checking the stated Gaussian width sensitivity convention.

How to use the tool and how it works

  1. Enter x, width. Use the units and conventions below.
  2. Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
  3. Read derivative. Use the output convention below.

Require width>0 for exp(-(x/width)²). Let z=x/width; return 2*z²*exp(-z²)/width as the width partial derivative, or zero when z is nonfinite or abs(z)>40.1

Input fieldMeaning and unitsAccepted input
xFinite scalar input coordinate; use the mathematical scale specified above.Required. Finite number.
widthWidthRequired. Finite number; strictly above 0.
Output fieldInterpretationReturned shape
derivativeWidth partial of exp(-(x/width)^2); set to zero when x/width is nonfinite or has magnitude>40.Required. Finite number.
json
{
  "input": {
    "x": 2,
    "width": 2
  },
  "output": {
    "derivative": 0.36787944117144233
  }
}

Limitations and assumptions

  • Width is held in the same input-coordinate scale as x; the numerical tail cutoff is explicit and this is not an input derivative.
  • 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

  1. Calculation and input contract: activation/gaussian-activation-width-sensitivity — tool.io

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