!
!  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
!  SLEPc - Scalable Library for Eigenvalue Problem Computations
!  Copyright (c) 2002-2020, Universitat Politecnica de Valencia, Spain
!
!  This file is part of SLEPc.
!  SLEPc is distributed under a 2-clause BSD license (see LICENSE).
!  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
!
!  Program usage: mpiexec -n <np> ./test1f [-help]
!
!  Description: Test rational function in Fortran.
!
! ----------------------------------------------------------------------
!
      program main
#include <slepc/finclude/slepcfn.h>
      use slepcfn
      implicit none

! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
!     Declarations
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      FN             fn
      PetscInt       i,n,na,nb
      PetscMPIInt    rank
      PetscErrorCode ierr
      PetscScalar    x,y,yp,p(10),q(10),five
      PetscScalar    pp(10),qq(10),tau,eta

! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
!     Beginning of program
! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

      call SlepcInitialize(PETSC_NULL_CHARACTER,ierr)
      call MPI_Comm_rank(PETSC_COMM_WORLD,rank,ierr)
      call FNCreate(PETSC_COMM_WORLD,fn,ierr)

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!     Polynomial p(x)
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      na = 5
      p(1) = -3.1
      p(2) = 1.1
      p(3) = 1.0
      p(4) = -2.0
      p(5) = 3.5
      call FNSetType(fn,FNRATIONAL,ierr)
      call FNRationalSetNumerator(fn,na,p,ierr)
      call FNView(fn,PETSC_NULL_VIEWER,ierr)
      x = 2.2
      call FNEvaluateFunction(fn,x,y,ierr)
      call FNEvaluateDerivative(fn,x,yp,ierr)
      call PrintInfo(x,y,yp)

! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
!     Inverse of polynomial 1/q(x)
! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      na = 0
      nb = 3
      q(1) = -3.1
      q(2) = 1.1
      q(3) = 1.0
      call FNSetType(fn,FNRATIONAL,ierr)
      call FNRationalSetNumerator(fn,na,PETSC_NULL_SCALAR,ierr)
      call FNRationalSetDenominator(fn,nb,q,ierr)
      call FNView(fn,PETSC_NULL_VIEWER,ierr)
      x = 2.2
      call FNEvaluateFunction(fn,x,y,ierr)
      call FNEvaluateDerivative(fn,x,yp,ierr)
      call PrintInfo(x,y,yp)

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!     Rational p(x)/q(x)
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      na = 2
      nb = 3
      p(1) = 1.1
      p(2) = 1.1
      q(1) = 1.0
      q(2) = -2.0
      q(3) = 3.5
      call FNSetType(fn,FNRATIONAL,ierr)
      call FNRationalSetNumerator(fn,na,p,ierr)
      call FNRationalSetDenominator(fn,nb,q,ierr)
      tau = 1.2
      eta = 0.5
      call FNSetScale(fn,tau,eta,ierr)
      call FNView(fn,PETSC_NULL_VIEWER,ierr)
      x = 2.2
      call FNEvaluateFunction(fn,x,y,ierr)
      call FNEvaluateDerivative(fn,x,yp,ierr)
      call PrintInfo(x,y,yp)

      call FNRationalGetNumerator(fn,n,pp,ierr)
      if (rank .eq. 0) then
        write(*,100) 'Numerator',(PetscRealPart(pp(i)),i=1,n)
      end if
      call FNRationalGetDenominator(fn,n,qq,ierr)
      if (rank .eq. 0) then
        write(*,100) 'Denominator',(PetscRealPart(qq(i)),i=1,n)
      end if
 100  format (A15,10F6.1)

! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
!     Constant
! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      na = 1
      nb = 0
      five = 5.0
      call FNSetType(fn,FNRATIONAL,ierr)
      call FNRationalSetNumerator(fn,na,five,ierr)
      call FNRationalSetDenominator(fn,nb,PETSC_NULL_SCALAR,ierr)
      call FNView(fn,PETSC_NULL_VIEWER,ierr)
      x = 2.2
      call FNEvaluateFunction(fn,x,y,ierr)
      call FNEvaluateDerivative(fn,x,yp,ierr)
      call PrintInfo(x,y,yp)

!     *** Clean up
      call FNDestroy(fn,ierr)
      call SlepcFinalize(ierr)
      end

! -----------------------------------------------------------------

      subroutine PrintInfo(x,y,yp)
#include <slepc/finclude/slepcfn.h>
      use slepcfn
      implicit none
      PetscScalar    x,y,yp
      PetscReal      re,im
      PetscMPIInt    rank
      PetscErrorCode ierr

      call MPI_Comm_rank(PETSC_COMM_WORLD,rank,ierr)
      if (rank .eq. 0) then
        re = PetscRealPart(y)
        im = PetscImaginaryPart(y)
        if (abs(im).lt.1.d-10) then
          write(*,110) 'f', PetscRealPart(x), re
        else
          write(*,120) 'f', PetscRealPart(x), re, im
        endif
        re = PetscRealPart(yp)
        im = PetscImaginaryPart(yp)
        if (abs(im).lt.1.d-10) then
          write(*,110) 'f''', PetscRealPart(x), re
        else
          write(*,120) 'f''', PetscRealPart(x), re, im
        endif
      endif
 110  format (A2,'(',F4.1,') = ',F10.5)
 120  format (A2,'(',F4.1,') = ',F10.5,SP,F9.5,'i')
      return
      end

!/*TEST
!
!   test:
!      suffix: 1
!      nsize: 1
!      requires: !single
!
!TEST*/
