#$=head1 NAME
#$
#$compress - compress a helix filter
#$
#$=head1 SYNOPSIS
#$
#$C<call resize(aa)>
#$
#$=head1 PARAMETERS
#$
#$=over 4
#$
#$=item aa  - type(filter)  
#$
#$      helix filter
#$
#$=back
#$
#$=head1 DESCRIPTION
#$
#$Compress a helix filter, remove all filter coefs < epsilon
#$
#$=head1 LIBRARY
#$
#$B<geef90>
#$
#$=cut
module compress {
 use helix
contains
  subroutine resize( aa) {
    type( filter)                      :: aa, bb
    logical, dimension( size( aa%lag)) :: keep
    keep = ( abs( aa%flt) > epsilon( aa%flt))
    call allocatehelix( bb, count( keep))
    bb%flt = pack( aa%flt, keep)
    bb%lag = pack( aa%lag, keep)
    call deallocatehelix( aa); aa = bb
  }
}