NAG Library Manual, Mark 30.1
Interfaces:  FL   CL   CPP   AD 

NAG AD Library Introduction
Example description
    Program f07fd_p0w_fe

!     F07FD_P0W_F Example Program Text
!     Mark 30.1 Release. NAG Copyright 2024.

!     .. Use Statements ..
      Use iso_c_binding, Only: c_ptr
      Use nagad_library, Only: f07fd_p0w_f
      Use nag_library, Only: nag_wp, x04caf
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
      Type (c_ptr)                     :: ad_handle
      Integer                          :: i, ifail, info, lda, n
      Character (1)                    :: uplo
!     .. Local Arrays ..
      Real (Kind=nag_wp), Allocatable  :: a(:,:)
!     .. Executable Statements ..
      Write (nout,*) 'F07FD_P0W_F Example Program Results'
!     Skip heading in data file
      Read (nin,*)
      Read (nin,*) n
      lda = n
      Allocate (a(lda,n))

!     Read A from data file
      Read (nin,*) uplo
      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

!     Factorize A
!     The NAG name equivalent of dpotrf is f07fd_p0w_f
      ifail = 0
      Call f07fd_p0w_f(ad_handle,uplo,n,a,lda,info)

!     Print factor
      ifail = 0
      Call x04caf(uplo,'Nonunit',n,n,a,lda,'Factor',ifail)

    End Program f07fd_p0w_fe