relfactorInv {pedigreeTools}

Inverse relationship factor from a pedigree

Description

Get inverse of the left Cholesky factor of the relationship matrix for the pedigree ped.

Usage

relfactorInv(ped)

getLInv(ped)

Arguments

ped

pedigree

Details

Note that the inverse of the left Cholesky factor is returned, which is lower triangular, that is from A = LL' (lower inv(A) = inv(LL') = inv(L)' inv(L) (upper triangular).

Value

matrix (dtCMatrix - triangular sparse)

Functions

• getLInv(): Inverse relationship factor from a pedigree

Examples

ped <- pedigree(sire = c(NA, NA, 1,  1, 4, 5),
                dam =  c(NA, NA, 2, NA, 3, 2),
                label = 1:6)
(LInv <- getLInv(ped))
solve(Matrix::t(getL(ped)))

# Test for correctness
LInvExp <- matrix(data = c( 1.0000,  0.0000,  0.0000,  0.0000,  0.0000, 0.0000,
                            0.0000,  1.0000,  0.0000,  0.0000,  0.0000, 0.0000,
                           -0.7071, -0.7071,  1.4142,  0.0000,  0.0000, 0.0000,
                           -0.5774,  0.0000,  0.0000,  1.1547,  0.0000, 0.0000,
                            0.0000,  0.0000, -0.7071, -0.7071,  1.4142, 0.0000,
                            0.0000, -0.7303,  0.0000,  0.0000, -0.7303, 1.4606),
                  byrow = TRUE, nrow = 6)
stopifnot(!any(abs(round(LInv, digits = 4) - LInvExp) > .Machine$double.eps))
L <- t(chol(getA(ped)))
LInvExp <- solve(L)
stopifnot(!any(abs(LInv - LInvExp) > .Machine$double.eps))
stopifnot(is(LInv, "sparseMatrix"))