PRO nul_data,times=times,varname=vnames ,appname=appname, no_verify=no_verify
if not keyword_set(times) then begin
print, 'pick start and end times of data to nulify'
ctime,times,y,vname=vnames,npoints=2
if n_elements(vnames) ne 2 then return
if vnames(0) ne vnames(1) then return
vnames=vnames[0]
endif
tnams = tnames(vnames,dtype=dtype)
if not keyword_set(no_verify) then begin
print, 'Do you really want to NULL the following data quantities:'
print,tnams
print, 'in the following time periods:'
print,time_string(times)
ans='n'
read,ans,prompt='? '
if strlowcase(ans) ne 'y' then return
print,'ok'
endif
if dimen1(times) ne 2 then message,'Time must have at least 2 elements'
for i=0,n_elements(tnams)-1 do begin
vname = tnams[i]
if dtype[i] ne 1 then continue
get_data,vname,data=d, dlimits = dl
if size(/type,d) ne 8 then continue
nd2 = dimen2(times)
for ns=0,nd2-1 do begin
t = time_double(times(*,ns))
w = where(d.x gt t(0) and d.x lt t(1),c)
if c ne 0 then begin
if ndimen(d.y) eq 1 then d.y(w) = !values.f_nan
if ndimen(d.y) eq 2 then d.y(w,*) = !values.f_nan
endif
endfor
if keyword_set(appname) then vname=vname+appname
store_data,vname,data=d, dlimits=dl
endfor
return
end