[NumPy-Tickets] [NumPy] #1742: cholesky error ?

NumPy Trac numpy-tickets@scipy....
Fri Feb 11 13:43:39 CST 2011


#1742: cholesky error ?
---------------------------+------------------------------------------------
  Reporter:  pcrs          |       Owner:  pv    
      Type:  defect        |      Status:  closed
  Priority:  normal        |   Milestone:  2.0.0 
 Component:  numpy.linalg  |     Version:  1.5.1 
Resolution:  invalid       |    Keywords:        
---------------------------+------------------------------------------------

Comment(by charris):

 It only looks at the lower (upper) triangular part of the matrix and
 assumes symmetry. With your matrix it becomes positive definite either
 way.


 {{{
 In [2]: a = array([[cos(k), -sin(k)], [-sin(k), cos(k)]])

 In [3]: eigh(a)
 Out[3]:
 (array([ 0.65981628,  1.2508567 ]),
  array([[-0.70710678, -0.70710678],
        [-0.70710678,  0.70710678]]))

 In [4]: a = array([[cos(k), +sin(k)], [+sin(k), cos(k)]])

 In [5]: eigh(a)
 Out[5]:
 (array([ 0.65981628,  1.2508567 ]),
  array([[-0.70710678,  0.70710678],
        [ 0.70710678,  0.70710678]]))

 }}}

-- 
Ticket URL: <http://projects.scipy.org/numpy/ticket/1742#comment:3>
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