[Numpy-tickets] [NumPy] #638: var should take absolute value for complex numbers.
NumPy
numpy-tickets@scipy....
Sun Dec 30 21:02:08 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 kumanna):
Dear Robert,
Replying to [comment:7 rkern]:
> 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.
Well, I do not wish to argue over this, since you have provided a
workaround. However, I would still like you to see the following before
closing this ticket:
http://books.google.com/books?id=seoUuxiqG-
oC&pg=PA408&dq=Variance+of+complex+random+variables&lr=&as_brr=0&sig=FTeiSD2WgxYYSg_F9vp5GiBMjAY
http://books.google.com/books?id=CVJf2vHEF4cC&pg=PA32&dq=Variance+of+complex+random+variables&lr=&as_brr=0&sig=tt4_9H3Ko5KQrW_aDN7JQKC933o
http://books.google.com/books?id=JKhw0jiqlckC&pg=PA194&dq=Variance+of+complex+random+variables&lr=&as_brr=0&sig=eumdxuzzpm1KtzMIbOY1KwAncDY
and more from:
http://books.google.com/books?as_q=Variance+of+complex+random+variables&num=10&btnG=Google+Search&as_epq=&as_oq=&as_eq=&as_libcat=0&as_brr=0&lr=&as_vt=&as_auth=&as_pub=&as_sub=&as_drrb=c&as_miny=&as_maxy=&as_isbn=
Of course, if you feel that is for `random variables' and not relevant for
a deterministic array, like in our case, you may close this ticket.
> You can use {{{cov()}}} by separating the real and imaginary components.
{{{cov([z.real, z.imag])}}}.
Right, what you mean. But still, I would request you to give it one more
thought before closing my request. :-)
Thanks for the time!
Kumar
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Ticket URL: <http://scipy.org/scipy/numpy/ticket/638#comment:8>
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