matrix multiplication



Thanks Jay.  Try it again after load("vect");.

On 3/22/07, Jay Belanger <belanger at truman.edu> wrote:
>
> "Ryan Krauss" <ryanlists at gmail.com> writes:
> ...
> > Ry(thy):=matrix([cos(thy),0,-sin(thy)],[0,1,0],[sin(thy),0,cos(thy)])$
> ...
> > R2:Ry(th);
> ...
> > cv:matrix([0],[0],[1]);
> ...
> > R2.cv;
> ...
> > and I get the message that the dimensions are incompatible.
> >
> > What am I doing wrong?  R2 appears to be 3x3 on the screen and cv
> > displays as a 3x1.
>
> I just tried it here, first with a couple days old cvs Maxima, then
> with the latest cvs Maxima, both compiled with sbcl, and had no problems.
>
> (%i1) Ry(thy):=matrix([cos(thy),0,-sin(thy)],[0,1,0],[sin(thy),0,cos(thy)])$
>
> (%i2) R2:Ry(th);
>                            [ cos(th)  0  - sin(th) ]
>                            [                       ]
> (%o2)                      [    0     1      0     ]
>                            [                       ]
>                            [ sin(th)  0   cos(th)  ]
> (%i3) cv:matrix([0],[0],[1]);
>                                      [ 0 ]
>                                      [   ]
> (%o3)                                [ 0 ]
>                                      [   ]
>                                      [ 1 ]
> (%i4) R2.cv;
>                                  [ - sin(th) ]
>                                  [           ]
> (%o4)                            [     0     ]
>                                  [           ]
>                                  [  cos(th)  ]
>
> Jay
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