Program f08lsfe
! F08LSF Example Program Text
! Mark 30.1 Release. NAG Copyright 2024.
! .. Use Statements ..
Use nag_library, Only: nag_wp, zgbbrd
! .. Implicit None Statement ..
Implicit None
! .. Parameters ..
Integer, Parameter :: nin = 5, nout = 6
Character (1), Parameter :: vect = 'N'
! .. Local Scalars ..
Integer :: i, info, j, kl, ku, ldab, ldc, ldpt, &
ldq, m, n, ncc
! .. Local Arrays ..
Complex (Kind=nag_wp), Allocatable :: ab(:,:), c(:,:), pt(:,:), q(:,:), &
work(:)
Real (Kind=nag_wp), Allocatable :: d(:), e(:), rwork(:)
! .. Intrinsic Procedures ..
Intrinsic :: max, min
! .. Executable Statements ..
Write (nout,*) 'F08LSF Example Program Results'
! Skip heading in data file
Read (nin,*)
Read (nin,*) m, n, kl, ku, ncc
ldab = kl + ku + 1
ldc = m
ldpt = n
ldq = m
Allocate (ab(ldab,n),c(m,ncc),pt(ldpt,n),q(ldq,m),work(m+n),d(n),e(n-1), &
rwork(m+n))
! Read A from data file
Read (nin,*)((ab(ku+1+i-j,j),j=max(i-kl,1),min(i+ku,n)),i=1,m)
! Reduce A to upper bidiagonal form
! The NAG name equivalent of zgbbrd is f08lsf
Call zgbbrd(vect,m,n,ncc,kl,ku,ab,ldab,d,e,q,ldq,pt,ldpt,c,ldc,work, &
rwork,info)
! Print bidiagonal form
Write (nout,*)
Write (nout,*) 'Diagonal'
Write (nout,99999) d(1:min(m,n))
Write (nout,*) 'Superdiagonal'
Write (nout,99999) e(1:min(m,n)-1)
99999 Format (1X,8F9.4)
End Program f08lsfe