Matrices

Question 1

t(x)

Answer 1

transpose

Question 2

diag(x)

Answer 2

diagonal

Question 3

%*%

Answer 3

matrix multiplication

Question 4

solve(a,b)

Answer 4

solves a %*% x = b for x

Question 5

solve(a)

Answer 5

matrix inverse of a

Question 6

rowsum(x)

Answer 6

sum of rows for a matrix-like object; rowSums(x) is a faster

version

Question 7

colsum(x), colSums(x)

Answer 7

sum of columns for a matrix-like object; colSums(x) is a faster
version

Question 8

rowMeans(x)

Answer 8

fast version of row means

Question 9

colMeans(x)

Answer 9

fast version of col means