bg_sumstrexp

Sum of two stretched exponentials background model

Syntax

info = bg_sumstrexp()
P = bg_sumstrexp(t,param)
P = bg_sumstrexp(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) = A_1\exp \left(-\lambda\kappa_1 \vert t \vert^{d_1}\right) + (1-A_1)\exp\left(-\lambda\kappa_2 \vert t \vert^{d_2}\right)

Variable Symbol Default Lower bound Upper bound Description
param(1) \kappa_1 3.5 0 200 1st strexp decay rate
param(2) d_1 1 0 6 1st strexp stretch factor
param(3) \kappa_2 3.5 0 200 2nd strexp decay rate
param(4) d_2 1 0 6 2nd strexp stretch factor
param(5) A_1 0.5 0 1 Relative amplitude

Description

info = bg_sumstrexp()

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_sumstrexp(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_sumstrexp(t,param,lambda)

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