
Re: Working with arrays
Posted:
Jun 17, 2013 6:17 AM


On Sunday, June 16, 2013 2:12:22 AM UTC7, amannucci wrote: > I thought I understood variables. This sequence completely mystifies me: > > Clear[lA, xtest] > > lA = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; > > xtest = {4, 5, 6}; > > lA\[CenterDot]xtest (* First case *) > > {{a, b}, {c, d}} . {x, y} (* Second case *) > > > > The output is: > > > > {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}\[CenterDot]{4, 5, 6} > > > > {a x + b y, c x + d y} > > > > How do I force matrix multiplication to actually occur, as in the second answer? Why does Mathematica do the matrix multiply in the second case but not the first? > > > > Thanks for any help. > > > > Tony
I appreciate the replies I have received. Yes, CenterDot is the wrong operator! I am a little rusty here. I appreciate the helpful comments.

