Chapter 2 CT4 Q11 (iii)

Discussion in 'CS2' started by Peter Cook, Sep 7, 2022.

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  1. Peter Cook

    Peter Cook Made first post

    To find the stationary distribution we want to find values of pi_0, pi_1 & pi_2 in pi. Which satisfies pi=pi*P.

    Where P =
    0 0 1
    0 1-p p
    1-p p 0
    In the solution to this question the matrix equations are as follows:
    (1) pi_0 = (1-p)*pi_2
    (2) pi_1 = (1-p)*pi_1 + p*pi_2
    (3) pi_2 = pi_0 + p*pi_1

    But when doing the vector-matrix multiplication the result comes out as:
    (1) pi_0 = pi_2
    (2) pi_1 = (1-p)*pi_1 + p*pi_2
    (3) pi_2 = (1-p)*pi_0 + p*pi_1


    I feel like I'm missing something, please can you help show where this result comes from?
     
  2. Peter Cook

    Peter Cook Made first post

    Sorry should have stated which year, this is from the September 2011 paper
     
  3. Andrew Martin

    Andrew Martin ActEd Tutor Staff Member

    Hi Peter

    I think you may be using the rows instead of the columns of P in the matrix multiplication.

    When we have <row vector> * <matrix>, the result is going to be another row vector where the first element is given by the dot product of <row vector> and the first column of <matrix>. The second element will be the dot product of <row vector> and the second column of <matrix> and so on.

    Hope this helps!

    Andy
     
    Peter Cook likes this.

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