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Quadratic Discriminant Roundoff Scale Tool

Compute quadratic discriminant roundoff scale from explicit bounded inputs.

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Description

Return a magnitude scale for discriminant arithmetic.

Polynomial coefficients encode powers in a chosen order, with zeros, multiplicities and leading terms carrying different meanings. Local coefficient identities and necessary divisibility conditions can be checked without finding every root or proving a proposed factorization. Floating-point comparisons use the exact supplied values unless an explicit tolerance is provided.

Return a magnitude scale for discriminant arithmetic.

When to use this tool

Use Quadratic Discriminant Roundoff Scale when checking the stated coefficient, root-identity, index or divisibility term.

How to use the tool and how it works

  1. Enter a, b, c. 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 scale. Use the output convention below.

Return a magnitude scale for discriminant arithmetic. scale = abs(b²)+abs(4*a*c).1

Input fieldMeaning and unitsAccepted input
aARequired. Finite number.
bBRequired. Finite number.
cCRequired. Finite number.
Output fieldInterpretationReturned shape
scaleabs(b)^2+abs(4*a*c); a magnitude reference, not a certified roundoff bound or tolerance.Required. Finite number.
json
{
  "input": {
    "a": 2,
    "b": 3,
    "c": -4
  },
  "output": {
    "scale": 41
  }
}

Limitations and assumptions

  • This is a cancellation/reference scale, not a rigorous roundoff bound, tolerance or proof of discriminant sign; a may be zero.
  • 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 a complete symbolic or numerically appropriate polynomial method for root finding, full factorization and robust treatment of near-degenerate coefficients.

References

  1. Calculation and input contract: algebra/quadratic-discriminant-roundoff-scale — tool.io

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