CVP verified calculation capability
Signed percent change (V₂ − V₁)/|V₁|×100% with reverse solve for V₁ or V₂.
Math Capability ID math.percent_change version 1.1.1 CVP VERIFIED STALE Core
Percent change
% change = (V₂ − V₁) / |V₁| × 100%V₂ = V₁(1 + P/100) if V₁ > 0; V₁(1 − P/100) if V₁ < 0V₁ = V₂ / (1 + P/100)V₁ = V₂ / (1 − P/100)Modes: p · v1 · v2
Canonical symbols for this capability. Agent schemas remain the contract.
| Symbol | Quantity | Unit | Role |
|---|---|---|---|
v1 | — | — | input / output |
v2 | — | — | input / output |
p | — | — | input / output |
solution_type | — | — | output |
direction | — | — | output |
code | — | — | output |
formula_branch | — | — | output |
constraint | — | — | output |
percent_change | — | — | output |
entered_percent_change | — | — | output |
value | — | — | output |
delta | — | — | output |
abs_v1 | — | — | output |
signed_factor | — | — | output |
multiplier | — | — | output |
percent_of_initial | — | — | output |
solutions | — | — | output |
candidates | — | — | output |
rounding | — | — | output |
resolution_limited | — | — | output |
branches | — | — | output |
omitted_branches | — | — | output |
Inspectable numeric contract for this Capability@Version. Not a rewrite of the engine.
| Field | Declaration |
|---|---|
numeric_domain | real |
exactness | float64 |
algorithm | Signed |v1| change and both signed inverse branches; exact rational formulas of normalized binary64 inputs, one ties-even output rounding. |
valid_domain | Finite decimal binary64 operands; up to512 characters per string; matching aliases; nonzero initial value. All published numeric fields/candidates must be representable. |
singularity_policy | INITIAL_VALUE_ZERO; complete two/unique/infinite sets; NO_REAL_SOLUTION; NUMERIC_RANGE for nonzero under/overflow including any valid branch or secondary field: rescale. |
branch_policy | not applicable — real principal value only |
tolerance | not applicable — closed form; capability Evidence owns comparison, no global default |
convergence | not applicable — non-iterative |
conditioning | Near v1=0 and inverse P=±100 is sensitive to input rounding. Triple consistency uses8ULP for same-sign nonzero percentages, strict zero. Requested P preserved in final solve. |
rounding | ieee754_round_ties_to_even |
overflow | ieee754_nonfinite_or_coded_error |
reproducibility | deterministic algorithm + Capability@Version |
independent_oracle | Private independent CPython Fraction/float; public summary Evidence. |
golden_vectors | Evidence golden + boundary + property (and published_reference_case when listed) |
Declared scope for this capability. Do not use it outside this domain.
Assumptions
One numerical check. The calculator page holds worked steps and FAQ.
(72−60)/|60|×100% = 20%
CVP VERIFIED · production STALE · CVP protocol 1.0.0-proposed · Core assurance. Computational verification is defined by CVP. Supplemental domain review (internal) and named expert review are defined by the Review policy and do not by themselves determine CVP conformance.
Human page, REST, and MCP share the same engine and calculation_version.
Build verified hashes workspace artifacts only. After deploy, attest:production GETs canonical URLs twice — the public/cached view an Agent actually hits, and origin — including every /capabilities/{id} HTML page. Public Capability HTML version must match catalog before production attestation passes. Live Trust rows above fetch /.well-known/calculatorx-production-attestation.json
and the output schema const. Build hashes: release integrity. That proves currently published page / engine / schema / evidence / MCP agree — not that a historical version is independently immutable. Reference Calculation Standard — Production surface contract 6/6.
curl -sS -X POST 'https://www.calculatorx.com/api/v1/calc/percent-change' \
-H 'Content-Type: application/json' \
-d '{"inputs":{"oldV":60,"newV":72},"calculation_version":"1.1.1"}'{
"inputs": {
"oldV": 60,
"newV": 72
},
"calculation_version": "1.1.1"
}POST /api/v1/calc/percent-change. This is a POST calculate endpoint — do not GET it.
Full REST contract: REST API docs.
Declared calculation modes for this capability.
pv1v2Human-readable sources plus CVP reference evidence classes.
Sources
Derived identities
Reference evidence classes: O1 model · O2 expected_values · O2 numerical_behavior
Inspect, then execute. Same engine as REST and the human calculator.
curl -sS -X POST 'https://www.calculatorx.com/mcp' \
-H 'Content-Type: application/json' \
-H 'MCP-Protocol-Version: 2026-07-28' \
-H 'Mcp-Method: tools/call' \
-H 'Mcp-Name: inspect_capability' \
-d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"inspect_capability","arguments":{"capability_id":"math.percent_change"},"_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientInfo":{"name":"calculatorx-docs-example","version":"1.0.0"},"io.modelcontextprotocol/clientCapabilities":{}}}}'curl -sS -X POST 'https://www.calculatorx.com/mcp' \
-H 'Content-Type: application/json' \
-H 'MCP-Protocol-Version: 2026-07-28' \
-H 'Mcp-Method: tools/call' \
-H 'Mcp-Name: execute_calculation' \
-d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"execute_calculation","arguments":{"capability_id":"math.percent_change","inputs":{"oldV":60,"newV":72},"calculation_version":"1.1.1"},"_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientInfo":{"name":"calculatorx-docs-example","version":"1.0.0"},"io.modelcontextprotocol/clientCapabilities":{}}}}'Pin calculation_version (1.1.1) when the result must stay reproducible.
Inspect the trust tier and required assurance level before execution. Full protocol notes: MCP docs.