fitbackground

Fit a parametric background model function to a dipolar signal

Warning

This is a legacy function. Its use is not recommended for routine or accurate data analysis.

Syntax

B = fitbackground(V,t,@model)
[B,lambda,param,tstart] = fitbackground(V,t,@model)
[B,lambda,param,tstart] = fitbackground(V,t,@model,tstart)
[B,lambda,param,tstart] = fitbackground(V,t,@model,[tstart tend])
[B,lambda,param,tstart] = fitbackground(___,'Property',Value)
Parameters
  • V - Data to fit (M-element array)
  • t - Time axis, in microseconds (N-element array)
  • @model - Background model (function handle)
  • tstart - Time at which fit starts, in microseconds (scalar)
  • tend - Time at which fit ends, in microseconds (scalar)
Returns
  • B - Fitted background function evaluated over t (M-element array)
  • lambda - Fitted modulation depth (scalar)
  • param - Fitted parameter values (array)
  • tstart - Automatically determined starting time (if not given as input), in microseconds (scalar)

Description

[B,lambda,param,tstart] = fitbackground(V,t,@model)

Fits the time-domain parametric background model @model and the modulation depth lambda to a time-domain signal V with time-axis t, resulting in a fitted background B . When not specified, the optimal fitting start time tstart is computed automatically by means of the backgroundstart function and returned as an output. The fitted parameters of the model are returned as a last output argument.

[B,lambda,param] = fitbackground(V,t,@model,tstart)

The time at which the background starts to be fitted can be passed as an additional argument tstart.

[B,lambda,param] = fitbackground(V,t,@model,[tstart tend])

The start and end times of the fitting can be specified by passing a two-element array [tstart, tend] as the argument. If tend is not specified, the end of the signal is selected as the default.

Additional Settings

Additional settings can be specified via name-value pairs. All property names are case insensitive and the property-value pairs can be passed in any order after the required input arguments have been passed.

B = fitbackground(___,'Property1',Value1,'Property2',Value2,___)
  • 'ModDepth - Modulation depth

    Fixes the modulation depth to a user-defined value instead of fitting it along with the background parameters.

    Default: [] (empty) (automatically fitted)

    Example:

    B = fitbackground(___,'ModDepth',0.45)
  • 'InitialGuess - Initial parameter values

    User-given estimation of the background parameters, passed as an array. If not specified, the parametric model defaults are employed.

    Default: [] (empty)

    Example:

    B = fitbackground(___,'InitialGuess',[0.75 3])
  • 'LogFit - Fit in log-scale

    Specifies whether to use the signal (false) or the logarithm of the signal (true) during fitting.

    Default: false

    Example:

    B = fitbackground(___,tstart,'LogFit',true)
  • 'Solver' - Optimization solver

    Specifies the solver used for fitting the background model (lsqnonlin, fminsearchcon, nlsqbnd).

    Default: 'lsqnonlin' (Optimization Toolbox installed) or 'fminsearchcon' (Optimization Toolbox not installed)

    Example:

    B = fitbackground(___,'Solver','nlsqbnd')