Module interpolate 

Interpolation primitives (linear, cubic spline). Interpolation & Curve Fitting

Provides deterministic interpolation and polynomial fitting primitives:

• Piecewise linear interpolation
• Nearest-neighbor interpolation
• Least-squares polynomial fitting (via Vandermonde + QR)
• Polynomial evaluation (Horner’s method)
• Natural cubic spline interpolation

Determinism Contract

All summation reductions use BinnedAccumulatorF64 for bit-identical results across platforms and execution orders. No HashMap or non-deterministic iteration is used.

Structs

CubicSpline

Natural cubic spline representation.

Functions

interp1d_linear

Piecewise linear interpolation.

interp1d_nearest

Nearest-neighbor interpolation.

polyfit

Least-squares polynomial fit of given degree.

polyval

Evaluate polynomial at given points using Horner’s method.

spline_cubic_natural

Construct a natural cubic spline (second derivative = 0 at boundaries).

spline_eval

Evaluate a cubic spline at query points.