n=3; A = matrix( runif(n*n), c(n,n)) 
A
n=3; A = matrix( round(runif(n*n), 3) , c(n,n)) 
A
iA = solve(A)
iA
iA %*% A 
n=1000; A = matrix( round(runif(n*n), 3) , c(n,n)) 
iA = solve(A)
iA %*% A -> I
sum(diag(I))
A = rbind( c(1, 3), c(-3, 5) )
rm(list=ls())
A = rbind( c(1, 3), c(-3, 5) )
A
A[1,2]
A[1,]
A[2,]
A[,2]
A[,2] = - A[,2]
A
A
diag(A) = c(-7, 7)
A
D = matrix(1:6, nrow=2)
D
dim(D) = c(3,2)
D
dim(D) = c(1,6)
D
as.vector(D)
A <- matrix(c(4, 2, 1,
              5, 6, 7,
              1, 0, 3), nrow=3, byrow=TRUE)
A
print(A)
t(1:3) %*% 1:3 
as.vector(t(1:3) %*% 1:3) 
1:3 %*% t(1:3)
outer(1:3, 1:3)
outer(1:3, 1:3, '+')
q()