Mod 6: Matrices II

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The provided matices

A = 2,0,1,3
B = 5,2,4,-1

Add and subtract the matrices.

A <- matrix(c(2,0,1,3), ncol=2)
B <- matrix(c(5,2,4,-1), ncol=2)
A+B

##      [,1] [,2]
## [1,]    7    5
## [2,]    2    2

A-B

##      [,1] [,2]
## [1,]   -3   -3
## [2,]   -2    4

Use diag() function to build a matrix with 4,1,2,3 the diagonal.

vect <- c(4,1,2,3)
diag(vect)

##      [,1] [,2] [,3] [,4]
## [1,]    4    0    0    0
## [2,]    0    1    0    0
## [3,]    0    0    2    0
## [4,]    0    0    0    3

Generate sample matrix

dm <- diag(3,5,5)
a <- c(1,0,0,0,0)
sdm1 <- sweep(dm,1,a,"+")
b <- c(2,0,0,0,0)
sdm2 <- sweep(sdm1,2,b,"+")
sdm2[1,1] <- sdm2[sdm2[2],sdm2[2]]
sdm2

##      [,1] [,2] [,3] [,4] [,5]
## [1,]    3    1    1    1    1
## [2,]    2    3    0    0    0
## [3,]    2    0    3    0    0
## [4,]    2    0    0    3    0
## [5,]    2    0    0    0    3

GitHub

Related file(s) can be found at Git Me