# Thread: Matrix Mutliplication (Number of operations)

1. ## Matrix Mutliplication (Number of operations)

Hey guys,

This is a question i think fits into L+AA subforum, if not, I do apologise!

I have two n by n matrices, A and B. I need to specify the "number of operations" so I'm thinking (hoping) that will involve some sort of algebraic expression.

I've found so far:-

2x2 = 12 operations
3x3 = 45
4x4 = 112
5x5 = 225

Rubbish. All rubbish. Can anyone help me out?

2. Originally Posted by exphate
Hey guys,

This is a question i think fits into L+AA subforum, if not, I do apologise!

I have two n by n matrices, A and B. I need to specify the "number of operations" so I'm thinking (hoping) that will involve some sort of algebraic expression.

I've found so far:-

2x2 = 12 operations
3x3 = 45
4x4 = 112
5x5 = 225

Rubbish. All rubbish. Can anyone help me out?
Number of what kind of operations? There are only three elementary operations.

3. Sorry, what I mean is...

How many times you have to multiply and add to get AxB.

So for each element of a 2x2 AB, you have 3 operations (2 multiplications and 1 addition)