#$
#$=head1 NAME
#$
#$heliarr  - two helix convolutions
#$
#$=head1 SYNOPSIS
#$
#$Initialize: C<call heliarr_init(nx,aa1,aa2)>
#$
#$Operator  : C<ierr= heliarr_lop(adj,add, xx,yy)>
#$
#$=head1 PARAMETERS
#$
#$=over 4
#$
#$=item  aa1,aa2  - type(filter)  
#$
#$       Helix filters 
#$
#$=item  nx1      - integer       
#$
#$       Size of model space where aa1 will be applied
#$
#$=item  adj,add,xx,yy  
#$
#$       standard operator conventions;
#$
#$=back
#$
#$=head1 DESCRIPTION
#$
#$An array of helix convolutions.  aa1 Will be applied to  points
#$(1:nx1) operator two to the remaining data.
#$
#$=head1 SEE ALSO
#$
#$L<helicon>
#$
#$=head1 LIBRARY
#$
#$B<geef90>
#$
#$=cut
#$
module heliarr { # an array of two helix convolutions
  use helicon
  type (filter) :: aa1, aa2
  integer       :: nx
#% _init (nx, aa1, aa2)
#% _lop (xx, yy)
  integer stat1, stat2
  call helicon_init (aa1)
  stat1 = helicon_lop (adj, .true., xx, yy (:nx))
  call helicon_init (aa2)
  stat2 = helicon_lop (adj, .true., xx, yy (1+nx:)) 
}