Program f11jpfe
! F11JPF Example Program Text
! Mark 30.1 Release. NAG Copyright 2024.
! .. Use Statements ..
Use nag_library, Only: f11jnf, f11jpf, nag_wp
! .. Implicit None Statement ..
Implicit None
! .. Parameters ..
Integer, Parameter :: nin = 5, nout = 6
! .. Local Scalars ..
Real (Kind=nag_wp) :: dscale, dtol
Integer :: i, ifail, la, lfill, liwork, n, nnz, &
nnzc, npivm
Character (1) :: check, mic, pstrat
! .. Local Arrays ..
Complex (Kind=nag_wp), Allocatable :: a(:), x(:), y(:)
Integer, Allocatable :: icol(:), ipiv(:), irow(:), istr(:), &
iwork(:)
! .. Executable Statements ..
Write (nout,*) 'F11JPF Example Program Results'
! Skip heading in data file
Read (nin,*)
! Read order of matrix and number of nonzero entries
Read (nin,*) n
Read (nin,*) nnz
la = 3*nnz
liwork = 2*la + 7*n + 1
Allocate (a(la),x(n),y(n),icol(la),ipiv(n),irow(la),istr(n+1), &
iwork(liwork))
! Read the matrix A
Do i = 1, nnz
Read (nin,*) a(i), irow(i), icol(i)
End Do
! Read the vector y
Read (nin,*) y(1:n)
! Calculate Cholesky factorization
lfill = -1
dtol = 0.0E0_nag_wp
mic = 'N'
dscale = 0.0E0_nag_wp
pstrat = 'M'
! ifail: behaviour on error exit
! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
ifail = 0
Call f11jnf(n,nnz,a,la,irow,icol,lfill,dtol,mic,dscale,pstrat,ipiv,istr, &
nnzc,npivm,iwork,liwork,ifail)
! Check the output value of NPIVM
If (npivm/=0) Then
Write (nout,*) 'Factorization is not complete'
Else
! Solve P L D L^H P^T x = y
check = 'C'
ifail = 0
Call f11jpf(n,a,la,irow,icol,ipiv,istr,check,y,x,ifail)
! Output results
Write (nout,*) 'Solution of linear system'
Write (nout,99999) x(1:n)
End If
99999 Format (1X,'(',E16.4,',',E16.4,')')
End Program f11jpfe