stellinstall/r8mkherm2_8f_source.html

      subroutine r8mkherm2(fun,x,nx,y,ny,fherm)

C

C  create a data set for Hermite interpolation, from evaluation of

C  function and derivatives.  function of 2 indep. coordinates.

C

C  input:

C

!============

! idecl:  explicitize implicit INTEGER declarations:

      IMPLICIT NONE

      INTEGER, PARAMETER :: R8=selected_real_kind(12,100)

      INTEGER ny,nx,ix,iy

!============

! idecl:  explicitize implicit REAL declarations:

      real*8 fun,dfdx,dfdy,d2fdxdy

!============

      external fun                      ! passed real function(x,y)

      real*8 x(nx)                        ! x coordinate array

      real*8 y(ny)                        ! y coordinate array

C

C  the passed function fun must have the interface:

C

C        real function <name>(x,y,dfdx,dfdy,d2fdxdy)

C  where x,y are input, the function returns the function value,

C  and the arguments dfdx and dfdy return as output the function

C  derivative at the point (x,y).

C

C  output:

C

      real*8 fherm(0:3,nx,ny)             ! function data & derivatives

C

C  fherm(0,i,j) = function value f at x(i),y(j)

C  fherm(1,i,j) = derivative df/dx at x(i),y(j)

C  fherm(2,i,j) = derivative df/dy at x(i),y(j)

C  fherm(3,i,j) = derivative d2f/dxdy at x(i),y(j)

C

C----------------------------

C

      do ix=1,nx

         do iy=1,ny

            fherm(0,ix,iy)=fun(x(ix),y(iy),dfdx,dfdy,d2fdxdy)

            fherm(1,ix,iy)=dfdx

            fherm(2,ix,iy)=dfdy

            fherm(3,ix,iy)=d2fdxdy

         enddo

      enddo

C

      return

      end