# The form of a Matrix M help.

1. Apr 19, 2004

### n0_3sc

I need help finding the form of the matrix M, heres the question:
(n and n+1 is a subscript):

Xn =
[An]
[Bn]

Xn+1 = MXn

M is a 2 x 2 matrix. The question says - What is the precise form of the matrix M?

2. Apr 19, 2004

### HallsofIvy

You are going to need more information than that! For one thing, are An and Bn numbers? The real information you need is some definition of xn. Just "xn+1= Mxn isn't enough. Do you have formulas for An and Bn?

3. Apr 19, 2004

### n0_3sc

o sorry, the other information given is that the vectors with two components are A, & B so yes they are numbers. (which represents the concentration of a reactant-for the question).
After one time step (where n represents the timesteps thus n+1) 80% of A is transformed into B while 60% of B is tranformed into A.

Does this help?

4. Apr 23, 2004

### HallsofIvy

So An+1= 0.2An+ 0.6Bn (the 20% of A left over after 80% is transformed into B and the 60% of B that is transformed into A) and
Bn+1= 0.8An+ 0.4Bn.

Looks like M=
[0.2 0.6]
[0.8 0.4]

Last edited by a moderator: Apr 23, 2004