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

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revision 1751, Tue Jan 30 17:41:02 2007 UTC revision 1887, Thu Jun 7 09:04:34 2007 UTC
# Line 107  Line 107 
107    "dCHMsimpl" and  "dCHMsuper"  -- currently have no *decent* way to get at    "dCHMsimpl" and  "dCHMsuper"  -- currently have no *decent* way to get at
108    the matrix factors of the corresponding matrix factorization !!    the matrix factors of the corresponding matrix factorization !!
109    
110    - rbind(<sparse>, <dense>) does not work  (e.g. <dgC>, <dge>)
111    
112    - setAs(<Mcl>,  "[dln]Matrix" )  for <Mcl> in {Matrix or denseMatrix + sparseMatrix}
113    
114    - Tell users about the possibility to disable the "S4-generic but somewhat slow"
115      cbind/rbind, e.g. via
116    
117      setHook(packageEvent("Matrix", "onLoad"),
118              function(...) methods:::bind_activation(FALSE))
119    
120    - ensure that  M[0], M[FALSE], M[1:2]  works as for traditional Matrices
121    
122    - make sure  M[FALSE, FALSE]  works for all Matrices
123      {e.g. fails for M <- Diagonal(4)}
124    
125    - <sparse> %*% <dense>  {also in crossprod/tcrossprod}  currently always
126      returns <dense>, since --> Csparse_dense_prod --> cholmod_sdmult
127      and that does only return dense.
128      When the sparse matrix is very sparse, i.e. has many rows with only zero
129      entries, it would make much sense to return sparse.
130    
131    - sparse-symmetric + diagonal should stay sparse-symmetric
132      (only stays sparse): Matrix(0, 4, 4) + Diagonal(4, 1:4)
133      --> R/diagMatrix.R ('FIXME')
134      but also R/Ops.R  to ensure  sp-sym. + sp-sym. |-> sp-sym.  etc
135    
136    - For a square sparse matrix 'b' {typically dgCMatrix or dgTMatrix},
137      we'd want a function  "Mat_plus_t_Mat" <- function(b) {....}
138      which computes the symmetric sparse matrix   b + t(b)
139      in way that never works with size-doubled vectors from  b@i etc..
140    
141    - ! <symmetricMatrix>  loses symmetry, both for dense and sparse matrices.
142      !M  where M is "sparseMatrix", currently always gives dense. This only
143      makes sense when M is ``really sparse''.
144    
145    - column names of sparse matrices are not printed;
146      we now "mention" them (if they are non-empty).
147      Option:
148            build show( <sparseMatrix>) on a function, possibly
149            print.sparseMatrix(), which gets an argument such as
150            'col.names.show  = FALSE' which is documented and can be set to TRUE
151    
152    - 'arules' needs fast colSums() and rowSums() - for ngCMatrix;
153      do it for "nMatrix" and "lMatrix" and return *integer*

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