matrix multiplication



"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