rlkk_extrapolate

Builtin index · Signal processing

result = rlkk_extrapolate(Z, freqs, target_freqs, [lambda=1e-4])

Input: Z, freqs, target_freqs, lambda · Output: result

What it is

Z: a length-N complex vector (CVec); freqs: a length-N real vector (Hz); target_freqs: a length-M real vector (Hz), which may extend beyond the measured band; lambda (optional number).

Overloads

One call shape — this function is not overloaded.

Examples

From the documentation, and run by the build -- the output and the figure below are what the engine actually produced. Simplest first.

freqs = logspace(0, 4, 20)
R = 100
C = 1e-6
w = 2 * pi * freqs
Z = R / (1 + 1j * w * R * C)         # a simple RC impedance, as measured data


target = logspace(-1, 5, 10)         # extends past the measured band on both sides

Z_ext = rlkk_extrapolate(Z, freqs, target, lambda=1e-4)
print("extrapolated {length(Z_ext)} points, first = {Z_ext[0]}, last = {Z_ext[9]}")

extrapolated 10 points, first = 100.003341 + 0.005947j, last = 0.110709 - 2.404278j

from signal-processing

How it works

rlkk_extrapolate(Z, freqs, target_freqs, [lambda=1e-4]) — refits the DRT from (Z, freqs) and evaluates it at target_freqs, which may extend beyond the measured band — the "reconstruct truncated/incomplete data" use case. A single value (CVec), not a model: there is only one output.

From the note above this builtin in the interpreter, where the reasoning was written down as it was built.