sbgvd Interface

public interface sbgvd

SBGVD computes all the eigenvalues, and optionally, the eigenvectors of a real generalized symmetric-definite banded eigenproblem, of the form Ax=(lambda)B*x. Here A and B are assumed to be symmetric and banded, and B is also positive definite. If eigenvectors are desired, it uses a divide and conquer algorithm. The divide and conquer algorithm makes very mild assumptions about floating point arithmetic. It will work on machines with a guard digit in add/subtract, or on those binary machines without guard digits which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or Cray-2. It could conceivably fail on hexadecimal or decimal machines without guard digits, but we know of none.


Subroutines

public pure subroutine dsbgvd(jobz, uplo, n, ka, kb, ab, ldab, bb, ldbb, w, z, ldz, work, lwork, iwork, liwork, info)

Arguments

Type IntentOptional Attributes Name
character(len=1), intent(in) :: jobz
character(len=1), intent(in) :: uplo
integer(kind=ilp), intent(in) :: n
integer(kind=ilp), intent(in) :: ka
integer(kind=ilp), intent(in) :: kb
real(kind=dp), intent(inout) :: ab(ldab,*)
integer(kind=ilp), intent(in) :: ldab
real(kind=dp), intent(inout) :: bb(ldbb,*)
integer(kind=ilp), intent(in) :: ldbb
real(kind=dp), intent(out) :: w(*)
real(kind=dp), intent(out) :: z(ldz,*)
integer(kind=ilp), intent(in) :: ldz
real(kind=dp), intent(out) :: work(*)
integer(kind=ilp), intent(in) :: lwork
integer(kind=ilp), intent(out) :: iwork(*)
integer(kind=ilp), intent(in) :: liwork
integer(kind=ilp), intent(out) :: info

public pure subroutine ssbgvd(jobz, uplo, n, ka, kb, ab, ldab, bb, ldbb, w, z, ldz, work, lwork, iwork, liwork, info)

Arguments

Type IntentOptional Attributes Name
character(len=1), intent(in) :: jobz
character(len=1), intent(in) :: uplo
integer(kind=ilp), intent(in) :: n
integer(kind=ilp), intent(in) :: ka
integer(kind=ilp), intent(in) :: kb
real(kind=sp), intent(inout) :: ab(ldab,*)
integer(kind=ilp), intent(in) :: ldab
real(kind=sp), intent(inout) :: bb(ldbb,*)
integer(kind=ilp), intent(in) :: ldbb
real(kind=sp), intent(out) :: w(*)
real(kind=sp), intent(out) :: z(ldz,*)
integer(kind=ilp), intent(in) :: ldz
real(kind=sp), intent(out) :: work(*)
integer(kind=ilp), intent(in) :: lwork
integer(kind=ilp), intent(out) :: iwork(*)
integer(kind=ilp), intent(in) :: liwork
integer(kind=ilp), intent(out) :: info

Module Procedures

public interface stdlib_dsbgvd()

Arguments

None

public interface stdlib_ssbgvd()

Arguments

None