#9011: the numpy SVD decomposition docstring is wrong
------------------------------+---------------------------------------------
   Reporter:  was             |       Owner:  jason, was
       Type:  defect          |      Status:  new       
   Priority:  minor           |   Milestone:  sage-4.6.2
  Component:  linear algebra  |    Keywords:            
     Author:                  |    Upstream:  N/A       
   Reviewer:                  |      Merged:            
Work_issues:                  |  
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Changes (by rbeezer):

 * cc: jason (added)


Comment:

 This still looks wrong for a rectangular matrix, just based on the
 dimensions of the matrices.  The .H is an improvement, though.  I couldn't
 find anything any better in the NumPy docs online.

 u  and  v  are returned as square (by default) and `np.diag()` is going to
 be square, when it really needs to have the same dimensions as the
 original matrix.

 To wit, in Sage 4.6.2.alpha2:

 {{{
 sage: A = np.array([[2,0,0,0],[0,0,0,0]])
 sage: ans = np.linalg.svd(A)
 sage: ans[0]*np.diag(ans[1])*ans[2]
 ValueError                                Traceback (most recent call
 last)

 /home/sage/sage-4.6.2.alpha2/<ipython console> in <module>()

 ValueError: shape mismatch: objects cannot be broadcast to a single shape
 }}}

 Jason - can you send this upstream easily?

 Rob

-- 
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9011#comment:2>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica, 
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