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[matrix] Diff of /pkg/TODO
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Diff of /pkg/TODO

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revision 2005, Wed Jul 18 14:46:20 2007 UTC revision 2043, Sat Aug 11 03:18:26 2007 UTC
# Line 151  Line 151 
151    shows that the Cholesky factorization is computed ``too quickly''.    shows that the Cholesky factorization is computed ``too quickly''.
152    Can be a big pain for largish matrices, when it is unneeded.    Can be a big pain for largish matrices, when it is unneeded.
153    
154    - example(Cholesky, echo=FALSE) ; cm <- chol(mtm); str(cm); str(mtm)
155    
156      shows that chol() does not seems to make use of an already
157      present factorization and rather uses one with more '0' in x slot.
158    
159  - diag(m) <- val    currently automatically works via  m[cbind(i,i)] <- val  - diag(m) <- val    currently automatically works via  m[cbind(i,i)] <- val
160    However,    However,
161    we need methods for 'diag<-' at least for diagonalMatrix,    we need methods for 'diag<-' at least for diagonalMatrix,
162    triangularMatrix, and probably also "dense*general*Matrix" since the    triangularMatrix, and probably also "dense*general*Matrix" since the
163    above currently goes via "matrix" and back instead of using the 'x' slot    above currently goes via "matrix" and back instead of using the 'x' slot
164    directly.    directly.
165    
166    - image(M, aspect= "iso", colorkey = FALSE)
167      really should be default; {aspect: non-back comptible for users !!}
168      current default colorkey=TRUE is on abs(M[M > 0]).
169      Note: Think about an optional smart option which keeps "0 |-> transparent"
170      but allows colors to differentiate negative and positive entries.
171      --- and be documented! Maybe move from man/dgTMatrix-class.Rd to image.Rd ?
172    
173    - examples for solve( Cholesky(.), b, system = c("A", "LDLt"....))
174      probably rather in man/CHMfactor-class.Rd than man/Cholesky.Rd

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