Why O Why, can't Mathematica add to Matrices?
First I enter a simple Matrix, a simple 3X3, with the Input\Create Table\Matrix\Vector
Menu, being very careful to select Matrix. a = 3 X 3. Then I did a -- b = IdentityMatrix.
It gave me a very pretty Identity matrix, just like any $50 calculator.
Then I type d = a + b. It gave me the two matrices side by side with a + sign between them.
My TI-86 knows that when you have two matrices with + sign between them,
it means add them, not to echo them back to the screen for general inspection.
There has to be alot of work done on the front-end of this thing, before I would consider it
a piece of reliable software. It corrupts files all the time, it nevers tells you when it's having
problems. You just have to try everything you can think of, and must of the time that doesn't work!