Deterministic sensitivity analysis

This experimental example varies declared model parameters over finite grids while freezing every other coordinate at the baseline. It reports the complete evaluated points, decision ties, adjacent switch brackets, named scenarios and one-way grid extrema used by a tornado plot. It is deterministic sensitivity analysis—not probabilistic sensitivity analysis, EVPPI, EVSI or a global sensitivity index.

Run the normalized-record fixture from the repository root:

voiage --format json calculate-deterministic-sensitivity \
  specs/frontier/deterministic-sensitivity-analysis/v1/fixtures/normative/input.json \
  --output dsa-result.json

The installed package validates the exact v1 request contract without reading schema files from a source checkout. Unknown fields, missing units, mismatched parameter/output units, incomplete coordinate vectors, and incomplete alternative sets fail closed.

Python callback and tornado plot

from voiage import deterministic_sensitivity
from voiage.plot import plot_deterministic_sensitivity_tornado


def model(parameters):
    x, y = parameters["x"], parameters["y"]
    return {"a": 10 + x - y, "b": 8 + 2 * x + y}


result = deterministic_sensitivity(
    model,
    baseline_parameters={"x": 0.0, "y": 0.0},
    parameter_grids={"x": [-2.0, 0.0, 2.0], "y": [-1.0, 0.0, 1.0]},
    parameter_units={"x": "point", "y": "point"},
    alternative_names=["a", "b"],
    output_unit="net-benefit-point",
    direction="maximize",
)
ax = plot_deterministic_sensitivity_tornado(result)
ax.figure.savefig("dsa-tornado.png", bbox_inches="tight")

Each bar spans the minimum and maximum optimal metric actually observed on the declared one-way grid; the dashed line is the baseline optimum. The function does not interpolate between coordinates or infer a root. An exact tie or plateau is reported as observed; a change between adjacent non-tied points is reported only as a bracket.

Python is the only executable surface in v1. Rust, R and Julia are explicitly unsupported and Mojo remains external. Scientific review, cross-language parity, stable promotion and release are separate gates.