Program f07krfe
! F07KRF Example Program Text
! Mark 30.1 Release. NAG Copyright 2024.
! .. Use Statements ..
Use nag_library, Only: nag_wp, x04dbf, x04ebf, zpstrf
! .. Implicit None Statement ..
Implicit None
! .. Parameters ..
Complex (Kind=nag_wp), Parameter :: zero = (0.0E0_nag_wp,0.0E0_nag_wp)
Integer, Parameter :: nin = 5, nout = 6
! .. Local Scalars ..
Real (Kind=nag_wp) :: tol
Integer :: i, ifail, info, j, lda, n, rank
Character (1) :: uplo
! .. Local Arrays ..
Complex (Kind=nag_wp), Allocatable :: a(:,:)
Real (Kind=nag_wp), Allocatable :: work(:)
Integer, Allocatable :: piv(:)
Character (1) :: clabs(1), rlabs(1)
! .. Executable Statements ..
Write (nout,*) 'F07KRF Example Program Results'
! Skip heading in data file
Read (nin,*)
Read (nin,*) n, uplo
lda = n
Allocate (a(lda,n),piv(n),work(2*n))
! Read A from data file
If (uplo=='U') Then
Read (nin,*)(a(i,i:n),i=1,n)
Else If (uplo=='L') Then
Read (nin,*)(a(i,1:i),i=1,n)
End If
tol = -1.0_nag_wp
! Factorize A
! The NAG name equivalent of zpstrf is f07krf
Call zpstrf(uplo,n,a,lda,piv,rank,tol,work,info)
! Zero out columns rank+1 to n
If (uplo=='U') Then
Do j = rank + 1, n
a(rank+1:j,j) = zero
End Do
Else If (uplo=='L') Then
Do j = rank + 1, n
a(j:n,j) = zero
End Do
End If
! Print rank
Write (nout,*)
Write (nout,'(1X,A15,I3)') 'Computed rank: ', rank
! Print factor
Write (nout,*)
Flush (nout)
ifail = 0
Call x04dbf(uplo,'Nonunit',n,n,a,lda,'Bracketed','F5.2','Factor', &
'Integer',rlabs,'Integer',clabs,80,0,ifail)
! Print pivot indices
Write (nout,*)
Write (nout,*) 'PIV'
Flush (nout)
ifail = 0
Call x04ebf('General','Non-unit',1,n,piv,1,'I14',' ','No',rlabs,'No', &
clabs,80,1,ifail)
End Program f07krfe