#	convolution:	Y(Z) = X(Z) * B(Z)
#
subroutine convolve( nb, bb, nx, xx, yy )
integer nb,	# number of coefficients in filter
	nx	# number of coefficients in input
		# number of coefficients in output will be nx+nb-1
real	bb(nb),	# filter coefficients
	xx(nx),	# input trace
	yy(1)	# output trace
integer ib, ix, iy, ny
ny = nx + nb -1
call null( yy, ny)
do ib= 1, nb
	do ix= 1, nx
		yy( ix+ib-1) = yy( ix+ib-1) + xx(ix) * bb(ib)
return; end