NAG Library Manual, Mark 28.7
Interfaces:  FL   CL   CPP   AD 

NAG FL Interface Introduction
Example description
    Program g03ehfe

!     G03EHF Example Program Text

!     Mark 28.7 Release. NAG Copyright 2022.

!     .. Use Statements ..
      Use nag_library, Only: g03eaf, g03ecf, g03ehf, nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: llen = 50, nin = 5, nout = 6
!     .. Local Scalars ..
      Real (Kind=nag_wp)               :: dmin, dstep
      Integer                          :: ellen, i, ifail, ld, ldx, lenc,      &
                                          liwk, m, method, n, n1, nsym, olenc
      Character (1)                    :: dist, orient, scal, update
!     .. Local Arrays ..
      Real (Kind=nag_wp), Allocatable  :: cd(:), d(:), dord(:), s(:), x(:,:)
      Integer, Allocatable             :: ilc(:), iord(:), isx(:), iuc(:),     &
      Character (llen), Allocatable    :: c(:)
!     .. Executable Statements ..
      Write (nout,*) 'G03EHF Example Program Results'
      Write (nout,*)

!     Skip heading in data file
      Read (nin,*)

!     Read in the problem size
      Read (nin,*) n, m

!     Read in information on the type of distance matrix to use
      Read (nin,*) update, dist, scal

      ldx = n
      ld = n*(n-1)/2
      n1 = n - 1
      liwk = 2*n
      Allocate (x(ldx,m),isx(m),s(m),d(ld),ilc(n1),iuc(n1),cd(n1),iord(n),     &

!     Read in the data used to construct distance matrix
      Read (nin,*)(x(i,1:m),i=1,n)

!     Read in variable inclusion flags
      Read (nin,*) isx(1:m)

!     Read in scaling
      If (scal=='G' .Or. scal=='g') Then
        Read (nin,*) s(1:m)
      End If

!     Compute the distance matrix
      ifail = 0
      Call g03eaf(update,dist,scal,n,m,x,ldx,isx,s,d,ifail)

!     Read in information on the clustering method to use
      Read (nin,*) method

!     Perform clustering
      ifail = 0
      Call g03ecf(method,n,d,ilc,iuc,cd,iord,dord,iwk,ifail)

!     Produce some example dendrogram
      olenc = 0
d_lp: Do
        Read (nin,*,Iostat=ifail) orient, dmin, dstep, nsym
        If (ifail/=0) Then
          Go To 100
        End If

!       Display the dendrogram
        Select Case (orient)
        Case ('N')
          Write (nout,*) 'Dendrogram, Orientation North'
          lenc = nsym
          ellen = n
        Case ('E')
          Write (nout,*) 'Dendrogram, Orientation East'
          lenc = n
          ellen = nsym
        Case ('S')
          Write (nout,*) 'Dendrogram, Orientation South'
          lenc = nsym
          ellen = n
        Case ('W')
          Write (nout,*) 'Dendrogram, Orientation West'
          lenc = n
          ellen = nsym
        End Select

!       Check that each element in the character array is sufficiently large
        If (llen<ellen) Then
          Write (nout,*)                                                       &
            'Each element of character array C needs to be at least ', ellen
          Write (nout,*) 'elements long, current length is ', llen
          Go To 100
        End If

        If (olenc<lenc) Then
!         Reallocate matrix
          Deallocate (c)
          Allocate (c(lenc))
        End If

!       Generate character array holding the dendrogram
        ifail = 0
        Call g03ehf(orient,n,dord,dmin,dstep,nsym,c,lenc,ifail)

        Write (nout,99999) c(1:lenc)
        Write (nout,*)
      End Do d_lp

100   Continue

99999 Format (1X,A)
    End Program g03ehfe