description:
sdrop seq
sequence version of drop
ie, drop all kets with coeff <= 0, and |>, from the given sequence
examples:
sdrop (|a> . 0|b> . -2|c> . 7.1|d>)
|a> . 7.1|d>
sdrop (|a> . |> . |b> . |> . |> . |c> . |>)
|a> . |b> . |c>
see also:
drop