[Boost-bugs] [Boost C++ Libraries] #3510: Introduce new diag function for creating diagonal matrices and for returning the diagonal of a matrix

Subject: [Boost-bugs] [Boost C++ Libraries] #3510: Introduce new diag function for creating diagonal matrices and for returning the diagonal of a matrix
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-10-05 08:37:11

#3510: Introduce new diag function for creating diagonal matrices and for
returning the diagonal of a matrix
--------------------------------------+-------------------------------------
 Reporter:  marco.guazzone@…          |       Owner:  guwi17        
     Type:  Feature Requests          |      Status:  new           
Milestone:  Boost 1.41.0              |   Component:  uBLAS         
  Version:  Boost 1.40.0              |    Severity:  Not Applicable
 Keywords:                            |  
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 Introduce a new '''diag''' free function in the spirit of the MATLAB's
 ''diag'' function and Mathematica's ''DiagonalMatrix function''.

 Basically it allows both the creation of a ''generalized'' diagonal matrix
 and the creation of a ''diagonal'' view of an existing matrix.

 A ''generalized'' k-th diagonal matrix is a special kind of matrix which
 has all elements set to zero but the ones on its k-th diagonal. The
 integer k is the offset from the main diagonal, that is:

 * k = 0: the elements on the main diagonal can be different from zero.

 * k > 0: only the elements on the k-th upper diagonal can be different
 from zero.

 * k < 0: only the elements on the k-th lower diagonal can be different
 from zero.

 A generalized diagonal matrix can be a rectangular matrix.



 Here below is a list of the requested cases:

 * Create a square diagonal matrix M with vector V
 being the k-th diagonal
   {{{M = diag(v,k)}}}

 * Like the above, but M has layout l (e.g., column major)
   {{{M = diag(v,k,l)}}}

 * Create a rectangular diagonal matrix M of size mXn with vector V being
 the k-th diagonal
   {{{M = diag(v,m,n,k)}}}


 * Like the above, but M has layout l (e.g., column major)
   {{{M = diag(v,m,n,k,l)}}}

 * Create a diagonal view of the k-th diagonal of matrix M
   {{{v = diag(M,k)}}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3510>
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