Aliases: drop0
### ** Examples m <- spMatrix(10,20, i= 1:8, j=2:9, x = c(0:2,3:-1)) m
10 x 20 sparse Matrix of class "dgTMatrix"
[1,] . 0 . . . . . . . . . . . . . . . . . .
[2,] . . 1 . . . . . . . . . . . . . . . . .
[3,] . . . 2 . . . . . . . . . . . . . . . .
[4,] . . . . 3 . . . . . . . . . . . . . . .
[5,] . . . . . 2 . . . . . . . . . . . . . .
[6,] . . . . . . 1 . . . . . . . . . . . . .
[7,] . . . . . . . 0 . . . . . . . . . . . .
[8,] . . . . . . . . -1 . . . . . . . . . . .
[9,] . . . . . . . . . . . . . . . . . . . .
[10,] . . . . . . . . . . . . . . . . . . . .
drop0(m)
10 x 20 sparse Matrix of class "dgCMatrix"
[1,] . . . . . . . . . . . . . . . . . . . .
[2,] . . 1 . . . . . . . . . . . . . . . . .
[3,] . . . 2 . . . . . . . . . . . . . . . .
[4,] . . . . 3 . . . . . . . . . . . . . . .
[5,] . . . . . 2 . . . . . . . . . . . . . .
[6,] . . . . . . 1 . . . . . . . . . . . . .
[7,] . . . . . . . . . . . . . . . . . . . .
[8,] . . . . . . . . -1 . . . . . . . . . . .
[9,] . . . . . . . . . . . . . . . . . . . .
[10,] . . . . . . . . . . . . . . . . . . . .
## A larger example: t5 <- new("dtCMatrix", Dim = c(5L, 5L), uplo = "L", x = c(10, 1, 3, 10, 1, 10, 1, 10, 10), i = c(0L,2L,4L, 1L, 3L,2L,4L, 3L, 4L), p = c(0L, 3L, 5L, 7:9)) TT <- kronecker(t5, kronecker(kronecker(t5,t5), t5)) IT <- solve(TT) I. <- TT %*% IT ; nnzero(I.) # 697 ( = 625 + 72 )
[1] 697
I.0 <- drop0(zapsmall(I.)) ## which actually can be more efficiently achieved by I.. <- drop0(I., tol = 1e-15) stopifnot(all(I.0 == Diagonal(625)), nnzero(I..) == 625)