[Numpy-discussion] finding eigenvectors etc

Matthieu Brucher matthieu.brucher@gmail....
Wed Feb 20 07:53:03 CST 2008


You should have such differences, that's strange. Are you sure you're using
the correct eigenvectors ?

Matthieu

2008/2/20, devnew@gmail.com <devnew@gmail.com>:
>
>
> > How are you using the values? How significant are the differences?
> >
>
>
> i am using these eigenvectors to do PCA on a set of images(of faces).I
> sort the eigenvectors in descending order of their eigenvalues and
> this is multiplied with the  (orig data of some images viz a matrix)to
> obtain a facespace.
> like
> #pseudocode...
> sortedeigenvectors=mysort(eigenvectors)
> facespace=sortedeigenvectors*adjfaces  /* adjfaces is a matrix */
>
> if i do this in python i get a facespace
> [[-1028755.44341439,  1480864.32750018,  1917712.0162213,
> -983526.60328021,
>   -1662357.13091294,  -499792.41540038,   208696.97376238,
> -916628.92613255,
>   -1454071.95225114, -1563209.39113008,  -231969.96968212 ,
> -768417.98606125]
>   [ -866174.88336972,  1212934.33524067,   543013.86361006,
> -1352625.86282073,
>    -309872.30710619 ,  466301.12884198,
> 216088.93319292 ,-1512378.8688779,
>    2581349.03171275,  1797812.01270033,  1876754.7339826 ,
> 751781.8166291 ]
>   [  -57026.32567001 ,  -69918.94570563,  -399715.51441018,
> -233720.8360051,
>     188227.41229887,   177341.47889165 ,  -65241.23138424 ,
> -311917.28253664,
>    1133399.70627111,  1089028.99019462,   684854.41725944 ,
> 413465.86494352]
>   [  405955.15245412,   562832.78296479 ,  864334.63457882 ,
> 629752.80210603,
>     894768.52572026,   578460.80766675 ,  629146.32442893 ,
> 768037.57754708,
>    -485157.28573271, -1718776.11176486 , -780929.18155991 ,
> -165391.19551137]]
>
> whereas the same steps
> in java
> [
> [-516653.73649950844, 274000.54127598763, -108557.2732037272,
> -799041.4108906921, -495577.7478765989, -49125.38109725664,
> -162041.57505147497, -917033.3002665655, 1207264.8912226136,
> 1384551.3481945703, 1056098.9289163304, 357801.9553511339],
> [-956064.0724430305, 1424775.0801567277, 898684.8188346579,
> -1385008.5401600213, -514677.038573372, 387195.56502804917,
> 281164.65362325957, -1512307.8891047493, 2114204.697920214,
> 1280391.7056360755, 1650660.0594245053, 554096.482085637],
> [-666313.7580419029, 1365981.2428742633, 2011095.455319733,
> -453217.29083790665, -1199981.2283586136, -358852.32104592584,
> 375855.4012532809, -311436.16701894277, -2033000.776565753,
> -2418152.391663846, -847661.841421182, -926486.0374297247],
> [593030.0669844414, 121955.63569302124, 124121.99904933537,
> 697146.7418886195, 1321002.514808584, 743093.1371151333,
> 493712.52017493406, 767889.8563902564, 487050.6874229272,
> -641935.1621667973, -310387.14691965195, 246026.0999929544]
> ]
>
> such difference causes diff results in all calculations involving the
> facespace
>
>
> dn
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-- 
French PhD student
Website : http://matthieu-brucher.developpez.com/
Blogs : http://matt.eifelle.com and http://blog.developpez.com/?blog=92
LinkedIn : http://www.linkedin.com/in/matthieubrucher
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