!   M01NDF Example Program Text
!   Mark 30.0 Release. NAG Copyright 2024.

    Module m01ndfe_mod

!     M01NDF Example Program Module:
!            Parameters and User-defined Routines

!     .. Use Statements ..
      Use nag_library, Only: nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Accessibility Statements ..
      Private
      Public                           :: ex1, ex2
!     .. Parameters ..
      Integer, Parameter, Public       :: nin = 5, nout = 6
    Contains
      Subroutine ex1(rv,n,m1,m2,item,m)
!       Example 1: Calling M01NDF in direct search mode

!       .. Use Statements ..
        Use nag_library, Only: m01ndf
!       .. Implicit None Statement ..
        Implicit None
!       .. Scalar Arguments ..
        Integer, Intent (In)           :: m, m1, m2, n
!       .. Array Arguments ..
        Real (Kind=nag_wp), Intent (In) :: item(m), rv(n)
!       .. Local Scalars ..
        Real (Kind=nag_wp)             :: h
        Integer                        :: i, ifail, lk, mode
        Logical                        :: valid
!       .. Local Arrays ..
        Integer                        :: dummy(1)
        Integer, Allocatable           :: idx(:), k(:)
!       .. Executable Statements ..

        Write (nout,*)
        Write (nout,*)
        Write (nout,*) 'Example 1'
        Write (nout,*)

        Allocate (idx(m))

!       Stop if an error occurs
        ifail = 0

!       First call M01NDF with MODE=0 to calculate the necessary values for H
!       and LK
        mode = 0
        lk = 1

!       Validate input parameters the first time M01NDF is called
        valid = .True.

!       Note the use of DUMMY instead of K in the first call to M01NDF
        Call m01ndf(valid,mode,rv,n,m1,m2,item,m,idx,h,dummy,lk,ifail)

!       Allocate K using the value of LK returned in the previous call
        Allocate (k(lk))

!       There is no need to validate input parameters again
        valid = .False.

!       Call M01NDF again with MODE=4 to populate K and to search RV
        mode = 4
        Call m01ndf(valid,mode,rv,n,m1,m2,item,m,idx,h,k,lk,ifail)

        Write (nout,99999)(item(i),idx(i),i=1,m)

        Deallocate (idx,k)

99999   Format (1X,'Search for item ',F7.1,' returned index: ',I4)

      End Subroutine ex1

      Subroutine ex2(rv,n,m1,m2,item,m)
!       Example 2: Calling M01NDF in binary search mode

!       .. Use Statements ..
        Use nag_library, Only: m01ndf
!       .. Implicit None Statement ..
        Implicit None
!       .. Scalar Arguments ..
        Integer, Intent (In)           :: m, m1, m2, n
!       .. Array Arguments ..
        Real (Kind=nag_wp), Intent (In) :: item(m), rv(n)
!       .. Local Scalars ..
        Real (Kind=nag_wp)             :: h
        Integer                        :: i, ifail, lk, mode
        Logical                        :: valid
!       .. Local Arrays ..
        Integer                        :: dummy(1)
        Integer, Allocatable           :: idx(:)
!       .. Executable Statements ..

        Write (nout,*)
        Write (nout,*)
        Write (nout,*) 'Example 2'
        Write (nout,*)

        Allocate (idx(m))

!       Stop if an error occurs
        ifail = 0

!       Validate input parameters
        valid = .True.

!       Mode 3 does not use H or K
        mode = 3
        h = 0.0_nag_wp
        lk = 1

!       Make a single call to M01NDF to search RV for the ITEMs without
!       using H or K
        Call m01ndf(valid,mode,rv,n,m1,m2,item,m,idx,h,dummy,lk,ifail)

        Write (nout,99999)(item(i),idx(i),i=1,m)

99999   Format (1X,'Search for item ',F7.1,' returned index: ',I4)

      End Subroutine ex2

    End Module m01ndfe_mod

    Program m01ndfe

!     M01NDF Example Main Program

!     This example reads the data file once and then searches the same data
!     twice using two different search algorithms.

!     .. Use Statements ..
      Use m01ndfe_mod, Only: ex1, ex2, nin, nout
      Use nag_library, Only: nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Local Scalars ..
      Integer                          :: i, m, m1, m2, n
!     .. Local Arrays ..
      Real (Kind=nag_wp), Allocatable  :: item(:), rv(:)
!     .. Executable Statements ..
      Write (nout,*) 'M01NDF Example Program Results'

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

!     Read in example parameters
      Read (nin,*) n, m1, m2
      Read (nin,*) m

      Allocate (rv(n),item(m))

!     Read in vector to be searched
      Read (nin,*)(rv(i),i=1,n)

      Write (nout,*)
      Write (nout,*) 'Vector to be searched is:'
      Write (nout,99999)(rv(i),i=1,n)

!     Read in items to search for
      Read (nin,*)(item(i),i=1,m)

      Call ex1(rv,n,m1,m2,item,m)

      Call ex2(rv,n,m1,m2,item,m)

      Deallocate (rv,item)

99999 Format (1X,8F7.1)

    End Program m01ndfe