LANEG: computes the Sturm count, the number of negative pivots encountered while factoring tridiagonal T - sigma I = L D L^T. This implementation works directly on the factors without forming the tridiagonal matrix T. The Sturm count is also the number of eigenvalues of T less than sigma. This routine is called from DLARRB. The current routine does not use the PIVMIN parameter but rather requires IEEE-754 propagation of Infinities and NaNs. This routine also has no input range restrictions but does require default exception handling such that x/0 produces Inf when x is non-zero, and Inf/Inf produces NaN. For more information, see: Marques, Riedy, and Voemel, "Benefits of IEEE-754 Features in Modern Symmetric Tridiagonal Eigensolvers," SIAM Journal on Scientific Computing, v28, n5, 2006. DOI 10.1137/050641624 (Tech report version in LAWN 172 with the same title.) More...

Public Member Functions
pure integer(ilp) function	dlaneg (n, d, lld, sigma, pivmin, r)

	la_dlaneg

	la_qlaneg

pure integer(ilp) function	slaneg (n, d, lld, sigma, pivmin, r)

	la_slaneg

Detailed Description

LANEG: computes the Sturm count, the number of negative pivots encountered while factoring tridiagonal T - sigma I = L D L^T. This implementation works directly on the factors without forming the tridiagonal matrix T. The Sturm count is also the number of eigenvalues of T less than sigma. This routine is called from DLARRB. The current routine does not use the PIVMIN parameter but rather requires IEEE-754 propagation of Infinities and NaNs. This routine also has no input range restrictions but does require default exception handling such that x/0 produces Inf when x is non-zero, and Inf/Inf produces NaN. For more information, see: Marques, Riedy, and Voemel, "Benefits of IEEE-754 Features in Modern Symmetric Tridiagonal Eigensolvers," SIAM Journal on Scientific Computing, v28, n5, 2006. DOI 10.1137/050641624 (Tech report version in LAWN 172 with the same title.)

Member Function/Subroutine Documentation

◆ dlaneg()

pure integer(ilp) function la_lapack::laneg::dlaneg	(	integer(ilp), intent(in)	n,
		real(dp), dimension(*), intent(in)	d,
		real(dp), dimension(*), intent(in)	lld,
		real(dp), intent(in)	sigma,
		real(dp), intent(in)	pivmin,
		integer(ilp), intent(in)	r
	)

◆ la_dlaneg()

la_lapack::laneg::la_dlaneg

◆ la_qlaneg()

la_lapack::laneg::la_qlaneg

◆ la_slaneg()

la_lapack::laneg::la_slaneg

◆ slaneg()

pure integer(ilp) function la_lapack::laneg::slaneg	(	integer(ilp), intent(in)	n,
		real(sp), dimension(*), intent(in)	d,
		real(sp), dimension(*), intent(in)	lld,
		real(sp), intent(in)	sigma,
		real(sp), intent(in)	pivmin,
		integer(ilp), intent(in)	r
	)

The documentation for this interface was generated from the following file:

la_lapack.f90