; lshift n_points
;
; makes a left shift of the data
;
; see also : rshift EXTRACT CHSIZE

if ($dim != 1) error "Implemented in 1D only"

message "Enter number of points for left shift"
set n = $_
set it = $itype_1d  itype 0
set sz = $si1_1d

extract (1+$n) $si1_1d   chsize $sz
itype $it
