LARRD: computes the eigenvalues of a symmetric tridiagonal matrix T to suitable accuracy. This is an auxiliary code to be called from DSTEMR. The user may ask for all eigenvalues, all eigenvalues in the half-open interval (VL, VU], or the IL-th through IU-th eigenvalues. To avoid overflow, the matrix must be scaled so that its largest element is no greater than overflow**(1/2) * underflow**(1/4) in absolute value, and for greatest accuracy, it should not be much smaller than that. See W. Kahan "Accurate Eigenvalues of a Symmetric Tridiagonal Matrix", Report CS41, Computer Science Dept., Stanford University, July 21, 1966. More...

Public Member Functions
pure subroutine	dlarrd (range, order, n, vl, vu, il, iu, gers, reltol, d, e, e2, pivmin, nsplit, isplit, m, w, werr, wl, wu, iblock, indexw, work, iwork, info)

	la_dlarrd

	la_qlarrd

pure subroutine	slarrd (range, order, n, vl, vu, il, iu, gers, reltol, d, e, e2, pivmin, nsplit, isplit, m, w, werr, wl, wu, iblock, indexw, work, iwork, info)

	la_slarrd

Detailed Description

LARRD: computes the eigenvalues of a symmetric tridiagonal matrix T to suitable accuracy. This is an auxiliary code to be called from DSTEMR. The user may ask for all eigenvalues, all eigenvalues in the half-open interval (VL, VU], or the IL-th through IU-th eigenvalues. To avoid overflow, the matrix must be scaled so that its largest element is no greater than overflow**(1/2) * underflow**(1/4) in absolute value, and for greatest accuracy, it should not be much smaller than that. See W. Kahan "Accurate Eigenvalues of a Symmetric Tridiagonal Matrix", Report CS41, Computer Science Dept., Stanford University, July 21, 1966.

Member Function/Subroutine Documentation

◆ dlarrd()

pure subroutine la_lapack::larrd::dlarrd	(	character, intent(in)	range,
		character, intent(in)	order,
		integer(ilp), intent(in)	n,
		real(dp), intent(in)	vl,
		real(dp), intent(in)	vu,
		integer(ilp), intent(in)	il,
		integer(ilp), intent(in)	iu,
		real(dp), dimension(*), intent(in)	gers,
		real(dp), intent(in)	reltol,
		real(dp), dimension(*), intent(in)	d,
		real(dp), dimension(*), intent(in)	e,
		real(dp), dimension(*), intent(in)	e2,
		real(dp), intent(in)	pivmin,
		integer(ilp), intent(in)	nsplit,
		integer(ilp), dimension(*), intent(in)	isplit,
		integer(ilp), intent(out)	m,
		real(dp), dimension(*), intent(out)	w,
		real(dp), dimension(*), intent(out)	werr,
		real(dp), intent(out)	wl,
		real(dp), intent(out)	wu,
		integer(ilp), dimension(*), intent(out)	iblock,
		integer(ilp), dimension(*), intent(out)	indexw,
		real(dp), dimension(*), intent(out)	work,
		integer(ilp), dimension(*), intent(out)	iwork,
		integer(ilp), intent(out)	info
	)

◆ la_dlarrd()

la_lapack::larrd::la_dlarrd

◆ la_qlarrd()

la_lapack::larrd::la_qlarrd

◆ la_slarrd()

la_lapack::larrd::la_slarrd

◆ slarrd()

pure subroutine la_lapack::larrd::slarrd	(	character, intent(in)	range,
		character, intent(in)	order,
		integer(ilp), intent(in)	n,
		real(sp), intent(in)	vl,
		real(sp), intent(in)	vu,
		integer(ilp), intent(in)	il,
		integer(ilp), intent(in)	iu,
		real(sp), dimension(*), intent(in)	gers,
		real(sp), intent(in)	reltol,
		real(sp), dimension(*), intent(in)	d,
		real(sp), dimension(*), intent(in)	e,
		real(sp), dimension(*), intent(in)	e2,
		real(sp), intent(in)	pivmin,
		integer(ilp), intent(in)	nsplit,
		integer(ilp), dimension(*), intent(in)	isplit,
		integer(ilp), intent(out)	m,
		real(sp), dimension(*), intent(out)	w,
		real(sp), dimension(*), intent(out)	werr,
		real(sp), intent(out)	wl,
		real(sp), intent(out)	wu,
		integer(ilp), dimension(*), intent(out)	iblock,
		integer(ilp), dimension(*), intent(out)	indexw,
		real(sp), dimension(*), intent(out)	work,
		integer(ilp), dimension(*), intent(out)	iwork,
		integer(ilp), intent(out)	info
	)

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

la_lapack.f90