DATA 605 FUNDAMENTALS OF COMPUTATIONAL MATHEMATICS

Discussion W10: 11.1 #2

Kyle Gilde

10/18/2017

## prettydoc 
##      TRUE

2. In Example 11.4, let a = 0 and b = 1/2. Find P, P^2 , and P^3 .

matrix_power <- function(M, exponent) {
  ans <- M
  for (i in 1:(exponent - 1)){
    ans <- M %*% ans
    }
  return(ans)
}

a <-  0 
b  <-  1/2

d <- c(1 - a, a, b, 1 - b)
P <- matrix(d, nrow = 2, byrow = T)
row_col <- c("Yes", "No")
row.names(P) <- row_col
colnames(P) <- row_col

P; matrix_power(P, 2); matrix_power(P, 3)
##     Yes  No
## Yes 1.0 0.0
## No  0.5 0.5
##      Yes   No
## Yes 1.00 0.00
## No  0.75 0.25
##       Yes    No
## Yes 1.000 0.000
## No  0.875 0.125

What would P^n be? What happens to P n as n tends to infinity? Interpret this result.

matrix_power(P, 10000)
##     Yes No
## Yes   1  0
## No    1  0
\[\begin{equation} P^n = \begin{bmatrix} 1, 0 \\ \frac{2n - 1}{2n}, \frac{1}{2n} \end{bmatrix} \end{equation}\]