# Product of more than two matrices

Discussion in 'Mac Programming' started by MorphingDragon, Sep 2, 2010.

1. ### MorphingDragon macrumors 603

Joined:
Mar 27, 2009
Location:
The World Inbetween
#1
This isn't really a computing question more of a maths question. For an assignment, we have to make classes that will work with vectors in the form of (i, j, k) and 3x3 matrices. Part of the requirements is a method that will take the product of 3 matrices (just to be really mean) Anyway, I cant remember how to get the product of 3 or more matrices. (Golly) I tried googling it and my maths textbooks are back at the youth hostel. (Its teaching break ATM)

So if A, B, C are matrices, what would the product of them be?

2. ### LPZ macrumors 65816

Joined:
Jul 11, 2006
#2
Well, matrix multiplication is not commutative, so the order of the terms matters. Matrix multiplication is associative, so how you group the terms doesn't matter.

So to calculate A*B*C you could do either (A*B)*C or A*(B*C). So you'd simply take your process for multiplying two matrices and use it twice:

MatrixMultiply(MatrixMultiply(A,B), C)

3. ### MorphingDragon thread starter macrumors 603

Joined:
Mar 27, 2009
Location:
The World Inbetween
#3
Thanks