NAG Library Manual, Mark 28.6
```    Program g02akfe

!     G02AKF Example Program Text

!     Mark 28.6 Release. NAG Copyright 2022.

!     .. Use Statements ..
Use nag_library, Only: g02akf, nag_wp, x04caf
!     .. Implicit None Statement ..
Implicit None
!     .. Parameters ..
Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
Real (Kind=nag_wp)               :: errtol, f, rankerr, ranktol
Integer                          :: i, ifail, ldg, ldx, maxit, maxits,   &
n, nsub, rank
!     .. Local Arrays ..
Real (Kind=nag_wp), Allocatable  :: g(:,:), x(:,:)
!     .. Executable Statements ..

Write (nout,*) 'G02AKF Example Program Results'
Write (nout,*)
Flush (nout)
!     skip heading in data file
!     read in the problem size

ldg = n
ldx = n

Allocate (g(ldg,n),x(ldx,n))
!     read in the rank constraint
!     read in the matrix G

!     use te defaults for errtol, ranktol, maxits, maxit
errtol = 0.0E0_nag_wp
ranktol = 0.0E0_nag_wp
maxits = 0
maxit = 0
!     calculate rank constrained nearest correlation matrix
ifail = 0
Call g02akf(g,ldg,n,rank,errtol,ranktol,maxits,maxit,x,ldx,f,rankerr,    &
nsub,ifail)
!     display results
ifail = 0
Call x04caf('General',' ',n,n,x,ldx,'NCM with rank constraint',ifail)
Write (nout,*)
Write (nout,99999) 'Number of subproblems solved:', nsub
Write (nout,*)
Write (nout,99998) 'Squared Frobenius norm of difference:', f
Write (nout,*)
Write (nout,99997) 'Rank error:', rankerr

99999 Format (1X,A,I12)
99998 Format (1X,A,F9.4)
99997 Format (1X,A,F35.4)
End Program g02akfe
```