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Reciprocal Ratio Rounding Envelope Tool

Invert a strictly positive closed ratio interval; no decimal display rounding.

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Description

Invert a strictly positive closed ratio interval; no decimal display rounding.

A ratio compares quantities under a stated numerator and denominator. Fractions, percentage numerals, and percentage-point changes use different conventions, and changing a part can also change its whole. Unit consistency, zero denominators, rounding, and the order of adjustments determine the result.

Invert a strictly positive closed ratio interval; no decimal display rounding.

When to use this tool

Use Reciprocal Ratio Rounding Envelope when you need this specific ratio, allocation, transformation, interval, or adjustment-order calculation with an explicit base.

How to use the tool and how it works

  1. Enter ratio, absoluteError. 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 reciprocalLower, reciprocalUpper. Use the output convention below.

Return reciprocalLower=1/(ratio+absoluteError) and reciprocalUpper=1/(ratio-absoluteError). Require nonnegative error and ratio strictly above that error.1

Input fieldMeaning and unitsAccepted input
ratioRatio under the stated units and direction.Required. Finite number.
absoluteErrorAbsolute ErrorRequired. Finite number; minimum 0.
Output fieldInterpretationReturned shape
reciprocalLowerReciprocal LowerRequired. Finite number.
reciprocalUpperReciprocal UpperRequired. Finite number.
json
{
  "input": {
    "ratio": 2,
    "absoluteError": 0.5
  },
  "output": {
    "reciprocalLower": 0.4,
    "reciprocalUpper": 0.6666666666666666
  }
}

Limitations and assumptions

  • The original interval must remain positive. This is a deterministic reciprocal bound, not a confidence interval, uncertainty estimate, or rounding-policy verification.
  • The field tables state structural bounds; the mechanics also specify cross-field constraints. Malformed inputs and unsupported domains cause errors. A successful false flag, empty branch value, or zero placeholder has the meaning stated above and is distinct from an input error.
  • 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. Signed zero is exported as zero.

Alternative or Complementary methods

Check numerator, denominator, units, and adjustment order before comparing results. Use a complete allocation or physical mixture model when a single arithmetic term leaves relevant constraints unspecified.

References

  1. Calculation and input contract: proportions/reciprocal-ratio-rounding-envelope — tool.io

Similar or alternative tools

  • Ratio Preserving Integer Rounding Residual

    Return crossResidual=roundedNumerator*denominator-numerator*roundedDenominator, requiring nonzero original and rounded denominators and integer rounded components.

  • Reciprocal Ratio Spread

    Return ratio=first/second, reciprocal=second/first, and signedSpread=ratio-reciprocal, requiring both scalars nonzero.