bg_strexp

Stretched-exponential background model

Syntax

info = bg_strexp()
P = bg_strexp(r,param)
P = bg_strexp(r,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) = \exp\left(-\lambda \kappa \vert t\vert^{d}\right)

Variable Symbol Default Lower bound Upper bound Description
param(1) \kappa 3.5 0 200 decay rate (1/us)
param(2) d 1 0 6 stretch factor

Although the bg_strexp model has the same functional form as bg_homfractal, it is distinct since its first parameter is a decay rate constant and not a spin concentration like for bg_homfractal.

Description

info = bg_strexp()

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_strexp(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_strexp(t,param,lambda)

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