Wallpaper Roll Calculator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t3-019

Effect

Computation or source lookup only

Input and validation requirements

A zero wall height combined with zero pattern repeat makes the effective strip length zero, causing division by zero and an undefined roll count; the calculator must reject the input.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "wall_perimeter_m": 16,
    "roll_width_m": 0.53,
    "wall_height_m": 2.4,
    "repeat_waste_m": 0.3,
    "roll_length_m": 10.05,
    "total_strips_needed": 31
  },
  "expected_outputs": {
    "strips_per_roll": 3,
    "rolls_required": 11
  },
  "working": "Cut length per strip = 2.4 + 0.3 = 2.7 m. Strips per roll = floor(10.05 / 2.7) = floor(3.7222...) = 3. Total strips from wall width = ceil(16 / 0.53) = ceil(30.1886...) = 31. Rolls required = ceil(31 / 3) = ceil(10.3333...) = 11."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche3/tranche3-results.json