about summary refs log tree commit diff
path: root/sourcecodes/bnt-master/nethelp3.3/pca.htm
blob: 84fe3e386712e0e20ad5f0310d85c0ec05b269d7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
<html>
<head>
<title>
Netlab Reference Manual pca
</title>
</head>
<body>
<H1> pca
</H1>
<h2>
Purpose
</h2>
Principal Components Analysis

<p><h2>
Synopsis
</h2>
<PRE>
PCcoeff = pca(data)
PCcoeff = pca(data, N)
[PCcoeff, PCvec] = pca(data)
</PRE>


<p><h2>
Description
</h2>

<CODE>PCcoeff = pca(data)</CODE> computes the eigenvalues of the covariance
matrix of the dataset <CODE>data</CODE> and returns them as <CODE>PCcoeff</CODE>.  These
coefficients give the variance of <CODE>data</CODE> along the corresponding 
principal components.  

<p><CODE>PCcoeff = pca(data, N)</CODE> returns the largest <CODE>N</CODE> eigenvalues.

<p><CODE>[PCcoeff, PCvec] = pca(data)</CODE> returns the principal components as
well as the coefficients.  This is considerably more computationally
demanding than just computing the eigenvalues.

<p><h2>
See Also
</h2>
<CODE><a href="eigdec.htm">eigdec</a></CODE>, <CODE><a href="gtminit.htm">gtminit</a></CODE>, <CODE><a href="ppca.htm">ppca</a></CODE><hr>
<b>Pages:</b>
<a href="index.htm">Index</a>
<hr>
<p>Copyright (c) Ian T Nabney (1996-9)


</body>
</html>