Sept 12 Class

Stephanie says:

The lesson that we learnt on Tuesday was about Matrix Multiplication. To start off your must consider theses “rules of engagement” which means that the matrix multiplication can only happen under certain circumstances.

Example A: A= [ a b] [e f ]=B
[ c d] x [g h]
2x2

your end result would be: [ae+bg af+bh]
[cg+dg x cf+dh]

Tip: You can also use your hands to assist you in creating a new matrix. Make a “L” with your hands, and move then as you change columns to columns and rows to rows. The left hand only moves up and down, while your right hand only moves left to right. It works really well if you can’t remember what to multiply by what next.

Rule: If Amn (row x column) is to be multiplied by Bpq, then the “Inner Dimensions” must be equal, that is n=p and;; the size of the product matrix is given by the “Outer Dimensions” or in this case mxq (which tells how big it will be)

To simplify what I just said; the “Inner Dimensions” tell you if the multiplication will work or not and the “Outer Dimensions” tell you what the new dimensions will be.

So in the case of A45 * B59, the multiplication would work because the inner dimensions are the same therefore the new matrix dimensions will be 4 x 9.

This concludes the end of my blog, and the next blogger will be number 16.

Thanks Stephanie