sbgst Interface

public interface sbgst

SBGST reduces a real symmetric-definite banded generalized eigenproblem Ax = lambdaBx to standard form Cy = lambday, such that C has the same bandwidth as A. B must have been previously factorized as STS by DPBSTF, using a split Cholesky factorization. A is overwritten by C = XTAX, where X = S(-1)*Q and Q is an orthogonal matrix chosen to preserve the bandwidth of A.


Subroutines

public pure subroutine dsbgst(vect, uplo, n, ka, kb, ab, ldab, bb, ldbb, x, ldx, work, info)

Arguments

Type IntentOptional Attributes Name
character(len=1), intent(in) :: vect
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(in) :: bb(ldbb,*)
integer(kind=ilp), intent(in) :: ldbb
real(kind=dp), intent(out) :: x(ldx,*)
integer(kind=ilp), intent(in) :: ldx
real(kind=dp), intent(out) :: work(*)
integer(kind=ilp), intent(out) :: info

public pure subroutine ssbgst(vect, uplo, n, ka, kb, ab, ldab, bb, ldbb, x, ldx, work, info)

Arguments

Type IntentOptional Attributes Name
character(len=1), intent(in) :: vect
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(in) :: bb(ldbb,*)
integer(kind=ilp), intent(in) :: ldbb
real(kind=sp), intent(out) :: x(ldx,*)
integer(kind=ilp), intent(in) :: ldx
real(kind=sp), intent(out) :: work(*)
integer(kind=ilp), intent(out) :: info

Module Procedures

public interface stdlib_dsbgst()

Arguments

None

public interface stdlib_ssbgst()

Arguments

None