Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2013-04-28 05:05:49

genericname
Member
Registered: 2012-05-16
Posts: 52

Matrix chain multiplication question

Let's say for example,
Matrices A1;A2;A3 with dimensions:

A1 = 5x10
A2 = 10x3
A3 = 3x10

Would M[2,3] be equal to (10*3*10) or (10*3)?

Offline

#2 2013-04-28 06:24:09

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 82,989

Re: Matrix chain multiplication question

Hi;

Okay I got the definitions of your 3 matrices.

What is M[2,3]?

You want the dimensions of A1 x A2 x A3?


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Online

#3 2013-04-29 07:11:25

genericname
Member
Registered: 2012-05-16
Posts: 52

Re: Matrix chain multiplication question

Dimensions A2 x A3. Sorry.

Offline

#4 2013-04-29 07:19:22

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 82,989

Re: Matrix chain multiplication question

Hi;

That would yield a 10 x 10


The number of columns of the 1st matrix must equal the number of rows of the 2nd matrix.
    And the result will have the same number of rows as the 1st matrix, and the same number of columns as the 2nd matrix.

http://www.mathsisfun.com/algebra/matri … lying.html


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Online

Board footer

Powered by FluxBB