Generate a tridiagonal matrix.

Generate a tridiagonal matrix with upperDiag as superdiagonal, lowerDiag as subdiagonal and mainDiag as diagonal.

Usage

tridiag(mainDiag, upperDiag, lowerDiag)

Arguments

mainDiag

Diagonal of tridiagonal matrix.

upperDiag

Superdiagonal of tridiagonal matrix. Must have length length(mainDiag) - 1.

lowerDiag

Subdiagonal of tridiagonal matrix. Must have length length(mainDiag) - 1.

Value

Tridiagonal matrix.

Examples

set.seed(987)
mainDiag <- sample(100:110, size = 6, replace = TRUE)
upperDiag <- sample(10:20, size = 5, replace = TRUE)
lowerDiag <- sample(1:10, size = 5, replace = TRUE)

tridiag(mainDiag, upperDiag, lowerDiag)  
#>      [,1] [,2] [,3] [,4] [,5] [,6]
#> [1,]  108   10    0    0    0    0
#> [2,]    2  108   12    0    0    0
#> [3,]    0    2  106   11    0    0
#> [4,]    0    0    5  101   17    0
#> [5,]    0    0    0   10  107   13
#> [6,]    0    0    0    0    3  100