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Ratio Metric Sensitivity Tool

Return local partial derivatives of numerator/denominator with respect to its two supplied components.

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Description

For numerator / denominator, return partial derivatives 1 / denominator and -numerator / denominator².

A sensitivity is a local derivative with respect to a specified variable while other quantities are held fixed. Normalized metrics can have different derivatives from unnormalized sums.

For numerator / denominator, return partial derivatives 1 / denominator and -numerator / denominator².

When to use this tool

Use Ratio Metric Sensitivity when you need one clearly defined metric derivative.

How to use the tool and how it works

  1. Enter numerator, denominator. 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 numeratorDerivative, denominatorDerivative. Use the output convention below.

For numerator / denominator, return partial derivatives 1 / denominator and -numerator / denominator². Require a nonzero denominator.1

Input fieldMeaning and unitsAccepted input
numeratorNumeratorRequired. Finite number.
denominatorDenominatorRequired. Finite number.
Output fieldInterpretationReturned shape
numeratorDerivativeNumerator DerivativeRequired. Finite number.
denominatorDerivativeDenominator DerivativeRequired. Finite number.
json
{
  "input": {
    "numerator": 10,
    "denominator": 2
  },
  "output": {
    "numeratorDerivative": 0.5,
    "denominatorDerivative": -2.5
  }
}

Limitations and assumptions

  • These are local derivatives, not propagated uncertainty bounds; input covariance and nonlinear effects are omitted.
  • 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

Verify the aggregate definition and held-fixed quantities before using the derivative in optimization or uncertainty propagation.

References

  1. Calculation and input contract: metrics/ratio-metric-sensitivity — tool.io

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