breakpoint_curve()

MAYAFLUX_API double MayaFlux::Kinesis::Discrete::breakpoint_curve ( std::span< const double >  window, std::span< const double >  coefs  )

noexcept

Piecewise linear curve through (x, y) points.

coefs: pairs (x, y) with ascending x. The input is window[0], held at the first and last y outside the span of x. Uneven spacing is fine; unsorted x is not. An empty array gives zero.

Definition at line 316 of file Kernels.cpp.

{
    const size_t points = coefs.size() / 2;
    if (points == 0)
        return 0.0;
 
    const double x = window.empty() ? 0.0 : window.front();
    if (x <= coefs[0])
        return coefs[1];
    if (x >= coefs[2 * (points - 1)])
        return coefs[2 * (points - 1) + 1];
 
    size_t i = 0;
    while (i + 2 < points && x > coefs[2 * (i + 1)])
        ++i;
 
    const double x0 = coefs[2 * i];
    const double x1 = coefs[2 * (i + 1)];
    const double y0 = coefs[2 * i + 1];
    const double y1 = coefs[2 * (i + 1) + 1];
    if (x1 <= x0)
        return y0;
    return y0 + (y1 - y0) * (x - x0) / (x1 - x0);
}

References points, and window.