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Periodic Boundary Two Image Distance Tool

One-axis minimum image in [-period/2,period/2); exact half-period ties select the negative image.

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Description

Return minimum-image signed displacement and distance.

Numerical grids and sampled modes require explicit coordinate, boundary and sign conventions. A staggered location, minimum-image gap or Nyquist label is one component of a discretization rather than a complete field solve or unique physical interpretation.

Return minimum-image signed displacement and distance.

When to use this tool

Use Periodic Boundary Two Image Distance when checking the stated grid-coordinate, periodic-image or sampled-mode convention.

How to use the tool and how it works

  1. Enter first, second, period. 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 signedDisplacement, distance. Use the output convention below.

Return minimum-image signed displacement and distance. Require period > 0; signedDisplacement = modulo(second-first+period/2,period)-period/2 and distance is its magnitude.1

Input fieldMeaning and unitsAccepted input
firstFirstRequired. Finite number.
secondSecondRequired. Finite number.
periodPeriodRequired. Finite number; strictly above 0.
Output fieldInterpretationReturned shape
signedDisplacementSigned DisplacementRequired. Finite number.
distanceDistanceRequired. Finite number.
json
{
  "input": {
    "first": 9,
    "second": 1,
    "period": 10
  },
  "output": {
    "signedDisplacement": 2,
    "distance": 2
  }
}

Limitations and assumptions

  • The exact half-period tie is negative; this is one periodic axis, not a full nearest-image search in an arbitrary cell.
  • 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 mesh, transform convention and boundary conditions for a consistent numerical simulation or physical interpretation.

References

  1. Calculation and input contract: computational-physics/periodic-boundary-two-image-distance — tool.io

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