# shaping filter
# minimize  SUM rr(i)**2  by finding ff and rr where
#
# rr = yy - xx (convolve) ff
#
subroutine shaper( nf,ff, nx,xx, ny, yy, rr, niter)
integer	i, iter,   nf,    nx,    ny,         niter
real	ff(nf), xx(nx), yy(ny), rr(ny)
temporary real	df(nf), dr(ny), sf(nf), sr(ny)
if( ny != nx+nf-1)   call erexit('data length error')
do i= 1, nf
	ff(i) = 0.
do i= 1, ny
	rr(i) =  yy(i)
do iter= 0, niter {
	call contran( 1, 0, nx,xx,  nf,df,  rr)		# df=xx*rr
	call contran( 0, 0, nx,xx,  nf,df,  dr)		# dr=xx*df
	call cgstep( iter, nf,ff,df,sf,  ny,rr,dr,sr)	# rr=rr-dr; ff=ff+df
	}
return; end