Struct FmmSpline 

pub struct FmmSpline {
    pub x: Vec<f64>,
    pub y: Vec<f64>,
    pub b: Vec<f64>,
    pub c: Vec<f64>,
    pub d: Vec<f64>,
}

Cubic spline coefficients in the Forsythe, Malcolm and Moler form.

On segment i the spline is

S(t) = y[i] + b[i] * t + c[i] * t^2 + d[i] * t^3,   t = x_eval - x[i]

the layout R’s splines.c writes and edgeR’s find_max reads. All vectors have one entry per knot; the last entry of b, c and d is the extrapolating polynomial right of the final knot.

References

Forsythe, Malcolm and Moler, Computer Methods for Mathematical Computations, Prentice-Hall, 1977, chapter 4.

Fields

x: Vec<f64>

Knot abscissae, strictly increasing.

y: Vec<f64>

Knot ordinates, i.e. the constant term of each segment polynomial.

b: Vec<f64>

Linear coefficients, one per knot.

c: Vec<f64>

Quadratic coefficients, one per knot.

d: Vec<f64>

Cubic coefficients, one per knot.

Implementations

impl FmmSpline

pub fn eval(&self, x: f64) -> f64

Evaluates the spline at one abscissa.

Outside the knot range the nearest end segment’s cubic is extended, as in R’s spline_eval. It diverges quickly, so far-out values are meaningless.

Params

• x - Abscissa to evaluate at

Returns

The spline value.

Trait Implementations

impl Clone for FmmSpline

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FmmSpline

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.