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Implicit Second Partial Diagonal Term Tool

Calculate implicit second partial diagonal term from explicit caller-supplied inputs.

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Description

Return a second derivative for a supplied implicit planar curve.

An implicit relation defines local derivatives only where its smoothness and nonzero-partial hypotheses apply. Gradient and Hessian components supplied as numbers do not establish that a point lies on the level set or that a regular implicit function exists there.

Return a second derivative for a supplied implicit planar curve.

When to use this tool

Use Implicit Second Partial Diagonal Term when evaluating the stated implicit-derivative or level-set term from supplied partial derivatives.

How to use the tool and how it works

  1. Enter fx, fy, fxx, fxy, fyy. 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 secondDerivative. Use the output convention below.

Return a second derivative for a supplied implicit planar curve. Require fy != 0; y1 = -fx/fy, secondDerivative = -(fxx+2*fxy*y1+fyy*y1²)/fy.1

Input fieldMeaning and unitsAccepted input
fxFxRequired. Finite number.
fyFyRequired. Finite number.
fxxFxxRequired. Finite number.
fxyFxyRequired. Finite number.
fyyFyyRequired. Finite number.
Output fieldInterpretationReturned shape
secondDerivativeSecond DerivativeRequired. Finite number.
json
{
  "input": {
    "fx": 2,
    "fy": 4,
    "fxx": 6,
    "fxy": 1,
    "fyy": 2
  },
  "output": {
    "secondDerivative": -1.375
  }
}

Limitations and assumptions

  • All partials must come from the same sufficiently differentiable level-set point; existence and mixed-partial conventions are supplied assumptions.
  • 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

Check the original level-set equation, differentiability and the relevant implicit-function hypotheses before interpreting these local derivative formulas.

References

  1. Calculation and input contract: calculus/implicit-second-partial-diagonal-term — tool.io

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