sdpar-methods {dti}R Documentation

Methods for Function ‘sdpar’ in Package ‘dti’

Description

This function estimates the parameters of a piecewise linear model for the dependence between error standard deviation and mean.

Usage

  ## S4 method for signature 'dtiData':
  sdpar(object,level=NULL,sdmethod="sd",interactive=TRUE)

Arguments

object An object of class dtiData
level Suggested value for slot level. As a default the value in object@level is used. The value determines the lower endpoint of the linear section in the model for error standard deviation as a function of the mean.
sdmethod Method for estimating voxelwise standard deviations if replicates of zero weighted images are available, either "sd" or "mad".
interactive If TRUE a density of values in zero weighted images is plotted together with the specification of the lower endpoint of the interval of linearity. A good choice of this point should correspond, if present, to the minimum between the first two modes of the density estimate. The value can be changed or accepted. If changed a new value for slot lambda is set.

Value

The function returns an object of class dtiData.

Methods

obj = "ANY"
Returns a warning
obj = "dtiData"
Estimate parameters of a model for the dependence between error standard deviation and mean.

Author(s)

Karsten Tabelow tabelow@wias-berlin.de
J"org Polzehl polzehl@wias-berlin.de

See Also

dtiData, readDWIdata, dti.smooth, dtiTensor,

Examples

  ## Not run: demo(dti_art)

[Package dti version 0.6-0 Index]