[Numpy-tickets] [NumPy] #638: var should take absolute value for complex numbers.

NumPy numpy-tickets@scipy....
Sat Dec 29 22:14:28 CST 2007


#638: var should take absolute value for complex numbers.
------------------------+---------------------------------------------------
 Reporter:  akumar      |       Owner:  somebody   
     Type:  defect      |      Status:  new        
 Priority:  normal      |   Milestone:  1.0.5      
Component:  numpy.core  |     Version:  none       
 Severity:  normal      |    Keywords:  var complex
------------------------+---------------------------------------------------
 Hi!

 I was just wondering why numpy.var gives me complex variances for complex
 numbers.

 e.g.

 {{{
 h1 = (randn(1000,1) + 1j *randn(1000,1)) / sqrt(2)
 var(h1)
 }}}
 gives: {{{ (-0.00757596036094-0.0234608549341j) }}}

 While I actually expect the output to be similar to that which is from
 {{{
 var(square(abs(h1)))
 }}}
 which gives: {{{ 0.994899762171 }}}

 I feel this is an error, though I may be wrong. :-)

 Thanks.

 Kumar

-- 
Ticket URL: <http://scipy.org/scipy/numpy/ticket/638>
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