spgvd Interface

public interface spgvd

SPGVD computes all the eigenvalues, and optionally, the eigenvectors of a real generalized symmetric-definite eigenproblem, of the form Ax=(lambda)Bx, ABx=(lambda)x, or BAx=(lambda)x. Here A and B are assumed to be symmetric, stored in packed format, 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 subroutine dspgvd(itype, jobz, uplo, n, ap, bp, w, z, ldz, work, lwork, iwork, liwork, info)

Arguments

Type IntentOptional Attributes Name
integer(kind=ilp), intent(in) :: itype
character(len=1), intent(in) :: jobz
character(len=1), intent(in) :: uplo
integer(kind=ilp), intent(in) :: n
real(kind=dp), intent(inout) :: ap(*)
real(kind=dp), intent(inout) :: bp(*)
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 subroutine sspgvd(itype, jobz, uplo, n, ap, bp, w, z, ldz, work, lwork, iwork, liwork, info)

Arguments

Type IntentOptional Attributes Name
integer(kind=ilp), intent(in) :: itype
character(len=1), intent(in) :: jobz
character(len=1), intent(in) :: uplo
integer(kind=ilp), intent(in) :: n
real(kind=sp), intent(inout) :: ap(*)
real(kind=sp), intent(inout) :: bp(*)
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_dspgvd()

Arguments

None

public interface stdlib_sspgvd()

Arguments

None