[R] Factor Rotation

[Barry Cooke]

How does one rotate the loadings from a principal component analysis?
Help on function prcomp() from package mva mentions rotation:

Arguments

retx		a logical value indicating whether the rotated
		variables should be returned.

Values

rotation	the matrix of variable loadings (i.e., a matrix 
		whose olumns contain the eigenvectors).  The 
		function princomp returns this in the element 
		loadings.

x		if retx is true the value of the rotated data
		(the data multiplied by the rotation matrix) 
		is returned.

but it is unclear to me exactly how the rotation is to be done.
For instance how would one specify a varimax rotation?  Or are
loadings, by default, rotated by the varimax method in prcomp()?

MASS v2 describes the function rotate() on p. 409-410; however R
complements does not cover this.  A search of CRAN indicates Peter
Ho <peter at esb.ucp.pt> asked the same question Sept 29, 1999, but
I found no reply.

Thanks. Using R 1.0.0 on Windows 9x.

Barry J. Cooke                      Current mailing address:
Ph.D. Candidate                     #219 - 1810 NW 23 Blvd 
Environmental Biology and Ecology   Gainesville, Florida, USA 
Department of Biological Sciences   32605 
University of Alberta
Edmonton, AB, T6G 2E9               http://www.ualberta.ca/~bcooke 
bcooke at gpu.srv.ualberta.ca
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