Struct NearestRegular 

pub struct NearestRegular<'a, T: Float, const N: usize> { /* private fields */ }

An arbitrary-dimensional multilinear interpolator / extrapolator on a regular grid.

Assumes C-style ordering of vals (z(x0, y0), z(x0, y1), …, z(x0, yn), z(x1, y0), …).

Operation Complexity

• O(2^N) for interpolation and extrapolation in all regions.

Memory Complexity

• Peak stack usage is O(N), which is minimally O(N).
• While evaluation is recursive, the recursion has constant max depth of N, which provides a guarantee on peak memory usage.

Timing

• Timing determinism is guaranteed to the extent that floating-point calculation timing is consistent. That said, floating-point calculations can take a different number of clock-cycles depending on numerical values.

Implementations

impl<'a, T: Float, const N: usize> NearestRegular<'a, T, N>

pub fn new( dims: [usize; N], starts: [T; N], steps: [T; N], vals: &'a [T], ) -> Result<Self, &'static str>

Build a new interpolator, using O(N) calculations and storage.

This method does not handle degenerate dimensions; all grids must have at least 2 entries.

Assumes C-style ordering of vals (z(x0, y0), z(x0, y1), …, z(x0, yn), z(x1, y0), …).

Errors

• If any input dimensions do not match
• If any dimensions have size < 2
• If any step sizes have zero or negative magnitude

pub fn interp(&self, x: &[&[T]; N], out: &mut [T]) -> Result<(), &'static str>

Interpolate on a contiguous list of observation points.

Assumes C-style ordering of vals (z(x0, y0), z(x0, y1), …, z(x0, yn), z(x1, y0), …).

Errors

• If the dimensionality of the point does not match the data
• If the dimensionality of point or data does not match the grid

pub fn interp_one(&self, x: [T; N]) -> Result<T, &'static str>

Interpolate the value at a point, using fixed-size intermediate storage of O(N) and no allocation.

Assumes C-style ordering of vals (z(x0, y0), z(x0, y1), …, z(x0, yn), z(x1, y0), …).

Errors

• If the dimensionality of the point does not match the data
• If the dimensionality of either one exceeds the fixed maximum
• If the index along any dimension exceeds the maximum representable integer value within the value type T