Robert Dodier wrote:
> On 4/3/07, Bowo Prasetyo <prazjp at gmail.com> wrote:
> > 'eigenvectors' failed to work on numeric 2x2 matrix below..
> >
> > m: matrix( [10.48273938962865,14.15187882832064],
> > [21.22781824248096,31.71055763210962] );
> > eigenvectors(m)
>
> For purely numerical matrices, probably the LAPACK stuff is
> the way to go. The function for computing eigen-stuff is dgeev
> if I remember correctly. There were some notes about LAPACK
> and dgeev in particular a while ago --- take a look at the mailing
> list archive.
;; loading #P"/usr/local/share/maxima/5.11.0cvs/share/lapack/eigensys.fasl"
(%o1) /usr/local/share/maxima/5.11.0cvs/share/lapack/lapack.mac
(%i2) display2d:false;
(%o2) false
(%i3) m: matrix( [10.48273938962865,14.15187882832064],
[21.22781824248096,31.71055763210962] );
(%o3) matrix([10.48273938962865,14.15187882832064],
[21.22781824248096,31.71055763210962])
(%i4) dgeev(m,true,true); /* eigen-values,right left and left eigen vectors */
(%o4) [[.7725598869933563,41.42073713474492],
matrix([-.8245648401323938,-.4159735579192843],
[.5657674649689923,-.9093767091321241]),
matrix([-.9093767091321241,-.5657674649689923],
[.4159735579192843,-.8245648401323938])]
(%i5) dgeev(m,true);/* eigen-values,right eigen vectors */
(%o5) [[.7725598869933563,41.42073713474492],
matrix([-.8245648401323938,-.4159735579192843],
[.5657674649689923,-.9093767091321241])]
(%i6) dgeev(m);/* eigen-values */
(%o6) [[.7725598869933563,41.42073713474492]]