wtfa Documentation


PLS_Toolbox Documentation: wtfa	< wrtpulse	xclgetdata >

wtfa

Purpose

Window target factor analysis.

Synopsis

[rho,angl,q,skl] = wtfa(spec,tspec,window,p,options)

Description

Inputs are a M by N data matrix spec, a K by N matrix of target spectra tspec, the window width window > 1, and the number of principal components, PCs, for modelling each window of spectra, p. The input p is used to govern the PCA model in each window:

牋牋牋牋牋牋牋牋 p >= 1:牋 (integer) number PCs is a constant p,

牋牋牋牋牋 0 < p < 1:牋 sets a relative criteria for selecting number of PCs in each window i.e. PCs that capture <p*100% of the variance in the window are not used, or

牋牋牋牋牋牋牋牋牋 p < 0:牋 sets an absolute value for number of PCs i.e. factors with singular values <|p| are not used. EWFA (see EWFA) can be used as a guide for setting p when p<0.

Outputs are the cosines rho between tspec and a p component PCA model of spec in each window, angl [= acos(rho)], and Q residuals q. Note that the output values near the end of the record (less than the half width of the window) are plotted as dashed lines and the window center is output in the variable skl.

This routine is based on work in: Lohnes, M.T., Guy, R.D., and Wentzell, P.D., "Window Target-Testing Factor Analysis: Theory and Application to the Chromatographic Analysis of Complex Mixtures with Multiwavelength Flourescence Detection", Anal. Chim. Acta, 389, 95-113 (1999).

Options

牋牋牋牋牋牋 options =牋 a structure array with the following fields:

牋牋牋牋牋牋牋牋牋牋 name:牋 'options', name indicating that this is an options structure,

牋牋牋牋牋牋牋牋牋 plots:牋 [ 'none' | {'angle'} | 'rho' | 'q' ], governs plotting,

牋牋牋牋牋牋牋牋牋牋牋牋牋牋牋牋 'angle', plots projection angle {default},

牋牋牋牋牋牋牋牋牋牋牋牋牋牋牋牋 'rho', plots direction cosine, and

牋牋牋牋牋牋牋牋牋牋牋牋牋牋牋牋 'q', plots Q residuals.

牋牋牋牋牋牋牋牋牋 scale:牋 [ ], is a M element time scale to plot against

The default options can be retreived using: options = wtfa('options');.