Re: [Numpy-discussion] svd and eigh

2008-05-03 Thread Matthieu Brucher
Hi, The opposite of an eigenvector is an eigenvector as well, with the same eigenvalue. Depending on the algorithm, both can be returned. Matthieu 2008/5/3 wilson <[EMAIL PROTECTED]>: > thanks for the links.. > but why the different signs for entries in eigenvectors? is it a > library specific

Re: [Numpy-discussion] svd and eigh

2008-05-03 Thread wilson
thanks for the links.. but why the different signs for entries in eigenvectors? is it a library specific thing? shouldn't they be identical? W ___ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-di

Re: [Numpy-discussion] svd and eigh

2008-05-02 Thread Nils Wagner
On Fri, 2 May 2008 23:34:19 -0700 (PDT) wilson <[EMAIL PROTECTED]> wrote: > I am trying out the eigenvectors related functions in >numpy.linalg.I > came across some portions where i have doubts. > 1). > i have an array X > if i calculate L=dot(X,X.transpose()) > can L be called the covariance m

[Numpy-discussion] svd and eigh

2008-05-02 Thread wilson
I am trying out the eigenvectors related functions in numpy.linalg.I came across some portions where i have doubts. 1). i have an array X if i calculate L=dot(X,X.transpose()) can L be called the covariance matrix of X?I read so in a paper by Turk&Pentland(equation 3 i think) can someone clarify t

Re: [Numpy-discussion] svd() and eigh()

2008-03-01 Thread Arnar Flatberg
On Sat, Mar 1, 2008 at 2:43 PM, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > hi > i have a set of images of faces which i make into a 2d array using > numpy.ndarray > each row represents a face image > faces= > [[ 173. 87. ... 88. 165.] > [ 158. 103. .. 73. 143.] > [ 180. 87

[Numpy-discussion] svd() and eigh()

2008-03-01 Thread [EMAIL PROTECTED]
hi i have a set of images of faces which i make into a 2d array using numpy.ndarray each row represents a face image faces= [[ 173. 87. ... 88. 165.] [ 158. 103. .. 73. 143.] [ 180. 87. .. 55. 143.] [ 155. 117. .. 93. 155.]] from which i can get the mean image => avgface=a