[SciPy-user] eigenvector values (negative where it should be positive)
Carlos "Guâno" Grohmann
carlos.grohmann@gmail....
Sun May 24 21:07:55 CDT 2009
Hello all
I'm working on some structural geology data, using numpy (I'm
following some class notes, so I can check my results). I have a set
of directional data (azimuth/dip):
12 42
18 40
22 48
15 30
10 42
20 30
First I read the data and create a matrix with the direction cosines like this:
#direction cosines relative to axis oriented north, east and down
# phi = longitude = azimuth (dip direction)
# theta = latitude = dip
# xi = cos(theta[i])*cos(phi[i])
# yi = cos(theta[i])*sin(phi[i])
# zi = sin(theta[i])
# Tmat = orientation matrix T
# Tmat = sum(xi2) sum(xi.yi) sum(xi.zi)
# sum(yi.xi) sum(yi2) sum(yi.zi)
# sum(zi.xi) sum(zi.yi) sum(zi2)
This is the matrix:
[[ 3.34172131 0.96327612 2.73061427]
[ 0.96327612 0.29736701 0.78834422]
[ 2.73061427 0.78834422 2.36091168]]
So far so good, but according to my example, the eigenvectors should look like:
Vector 1 Vector 2 Vector 3
X 0.749 -0.590 -0.300
Y 0.217 -0.210 0.953
Z 0.626 0.779 0.029
and I have this:
[[-0.74913585 -0.59037777 0.30041565]
[-0.21679731 -0.21002264 -0.95335692]
[-0.62593482 0.77932315 -0.02934318]]
So, the values are OK, but the negative signs I don't understand.
any ideas are welcome
TIA
Carlos
--
Carlos Henrique Grohmann - Geologist D.Sc.
a.k.a. Guano - Linux User #89721
ResearcherID: A-9030-2008
carlos dot grohmann at gmail dot com
http://www.igc.usp.br/pessoais/guano/
_________________
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Can’t stop the signal.
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