module refine2 { # Refine mesh.
# Input mm(m1,m2) is coarse.  Output dd(n1,n2) linear interpolated.
#
use lint2
real, dimension( :, :), pointer, private :: xy
#% _init( co1,cd1,co2,cd2, m1,m2, fo1,fd1,fo2,fd2, n1,n2)
  integer, intent( in)  :: m1,m2, n1,n2
  real,    intent( in)  :: co1,cd1,co2,cd2                 # coarse grid
  real,    intent( out) :: fo1,fd1,fo2,fd2                 # fine grid
  integer               :: i1,i2, id
  real                  :: xmin,xmax, ymin,ymax, x,y
  allocate (xy( n1*n2, 2))
  xmin = co1-cd1/2;   xmax = co1 +cd1*(m1-1) +cd1/2        # Great formula!
  ymin = co2-cd2/2;   ymax = co2 +cd2*(m2-1) +cd2/2
  fd1= (xmax-xmin)/n1;  fo1= (xmin*(n1-.5) + xmax/2)/n1    # Great formula!
  fd2= (ymax-ymin)/n2;  fo2= (ymin*(n2-.5) + ymax/2)/n2
  do i2=1,n2 {  y = fo2 + fd2*(i2-1)
  do i1=1,n1 {  x = fo1 + fd1*(i1-1)
        id = i1+n1*(i2-1)
        xy( id, :) = (/ x, y /)
        }}
  call lint2_init( m1,m2, co1,cd1, co2,cd2, xy)
#% _lop (mm, dd) 
  integer stat1
  stat1 = lint2_lop( adj, .true., mm, dd)
#% _close
deallocate (xy)
}