sygvd Interface

public interface sygvd

SYGVD 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 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 dsygvd(itype, jobz, uplo, n, a, lda, b, ldb, w, 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) :: a(lda,*)
integer(kind=ilp), intent(in) :: lda
real(kind=dp), intent(inout) :: b(ldb,*)
integer(kind=ilp), intent(in) :: ldb
real(kind=dp), intent(out) :: w(*)
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 ssygvd(itype, jobz, uplo, n, a, lda, b, ldb, w, 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) :: a(lda,*)
integer(kind=ilp), intent(in) :: lda
real(kind=sp), intent(inout) :: b(ldb,*)
integer(kind=ilp), intent(in) :: ldb
real(kind=sp), intent(out) :: w(*)
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_dsygvd()

Arguments

None

public interface stdlib_ssygvd()

Arguments

None