Program x04defe

!     X04DEF Example Program Text

!     Mark 27.3 Release. NAG Copyright 2021.

!     .. Use Statements ..
      Use nag_library, Only: f01zdf, nag_wp, x04def
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: nout = 6
!     .. Local Scalars ..
      Real (Kind=nag_wp)               :: aa
      Integer                          :: i, ifail, j, kl, ku, lda, ldab, m, n
      Character (1)                    :: job
!     .. Local Arrays ..
      Complex (Kind=nag_wp), Allocatable :: a(:,:), ab(:,:)
!     .. Intrinsic Procedures ..
      Intrinsic                        :: cmplx, max, min, real
!     .. Executable Statements ..
      Write (nout,*) 'X04DEF Example Program Results'

      Write (nout,*)
      Flush (nout)

!     Generate a square array of data.

      m = 5
      n = m
      kl = 1
      ku = 1

      lda = m
      Allocate (a(lda,n))

      Do j = 1, n

        Do i = max(1,j-ku), min(m,j+kl)
          aa = real(10*i+j,kind=nag_wp)
          a(i,j) = cmplx(aa,-aa,kind=nag_wp)
        End Do

      End Do

!     Convert to packed storage.

      ldab = kl + ku + 1
      Allocate (ab(ldab,n))

      job = 'P'

      ifail = 0
      Call f01zdf(job,m,n,kl,ku,a,lda,ab,ldab,ifail)

!     Print m by n band matrix with kl subdiagonals and ku superdiagonals.

      ifail = 0
      Call x04def(m,n,kl,ku,ab,ldab,'Band Matrix:',ifail)

    End Program x04defe