lasd4 Interface

public interface lasd4

This subroutine computes the square root of the I-th updated eigenvalue of a positive symmetric rank-one modification to a positive diagonal matrix whose entries are given as the squares of the corresponding entries in the array d, and that 0 <= D(i) < D(j) for i < j and that RHO > 0. This is arranged by the calling routine, and is no loss in generality. The rank-one modified system is thus diag( D ) * diag( D ) + RHO * Z * Z_transpose. where we assume the Euclidean norm of Z is 1. The method consists of approximating the rational functions in the secular equation by simpler interpolating rational functions.


Subroutines

public pure subroutine dlasd4(n, i, d, z, delta, rho, sigma, work, info)

Arguments

Type IntentOptional Attributes Name
integer(kind=ilp), intent(in) :: n
integer(kind=ilp), intent(in) :: i
real(kind=dp), intent(in) :: d(*)
real(kind=dp), intent(in) :: z(*)
real(kind=dp), intent(out) :: delta(*)
real(kind=dp), intent(in) :: rho
real(kind=dp), intent(out) :: sigma
real(kind=dp), intent(out) :: work(*)
integer(kind=ilp), intent(out) :: info

public pure subroutine slasd4(n, i, d, z, delta, rho, sigma, work, info)

Arguments

Type IntentOptional Attributes Name
integer(kind=ilp), intent(in) :: n
integer(kind=ilp), intent(in) :: i
real(kind=sp), intent(in) :: d(*)
real(kind=sp), intent(in) :: z(*)
real(kind=sp), intent(out) :: delta(*)
real(kind=sp), intent(in) :: rho
real(kind=sp), intent(out) :: sigma
real(kind=sp), intent(out) :: work(*)
integer(kind=ilp), intent(out) :: info

Module Procedures

public interface stdlib_dlasd4()

Arguments

None

public interface stdlib_slasd4()

Arguments

None