bg_poly3

Third-order polynomial (cubic) background model

Syntax

info = bg_poly3()
P = bg_poly3(t,param)
P = bg_poly3(t,param,lambda)
Inputs
  • t – Time axis (N-array)
  • param – Model parameters
  • lambda – Modulation amplitude (between 0 and 1)
Outputs
  • B – Model background (N-array)
  • info – Model information (struct)

Model

B(t) = p_0 + p_1(\lambda t) + p_2(\lambda t)^2 + p_3(\lambda t)^3

Variable Symbol Default Lower bound Upper bound Description
param(1) p_0 1 0 200 Intercept
param(2) p_1 -1 -200 200 1st order weight
param(3) p_2 -1 -200 200 2nd order weight
param(3) p_3 -1 -200 200 3rd order weight

Description

info = bg_poly3()

Returns an info structure containing the specifics of the model:

  • info.model – Full name of the parametric model.
  • info.nparam – Total number of adjustable parameters.
  • info.parameters – Structure array with information on individual parameters.
B = bg_poly3(t,param)

Computes the background model B from the axis t according to the parameters array param for a modulation amplitude lambda=1. The required parameters can also be found in the info structure.

B = bg_poly3(t,param,lambda)

Computes the background model B for a given modulation amplitude lambda.