[Numpy-tickets] [NumPy] #638: var should take absolute value for complex numbers.
NumPy
numpy-tickets@scipy....
Sun Dec 30 15:37:42 CST 2007
#638: var should take absolute value for complex numbers.
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Reporter: akumar | Owner: somebody
Type: defect | Status: new
Priority: normal | Milestone: 1.0.5
Component: numpy.core | Version: none
Severity: normal | Resolution:
Keywords: var complex |
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Comment (by rkern):
I honestly don't care about compatibility with Matlab or Octave where I
think they're wrong.
Note that the formula given in the Wikipedia article does not match the
sentence following it. I think the sentence makes more sense than the
formula. Complex numbers have two components. The appropriate (default)
measure of spread of a distribution of complex numbers would be an ellipse
(covariance matrix) rather than a circle (real scalar value). As far as
statistical distributions are concerned, complex numbers are no different
than 2-vectors. I need another reference to be convinced otherwise.
You can use {{{cov()}}} by separating the real and imaginary components.
{{{cov([z.real, z.imag])}}}.
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Ticket URL: <http://scipy.org/scipy/numpy/ticket/638#comment:7>
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