operator types: sigmoid

sigmoid:
    description:
        sigmoid operator
        operators that change coefficients of kets, but not the structure of the input sequence
        the most commonly used sigmoid operator is the clean sigmoid that just sets coefficients to either 1 or 0

    examples:
        the |sp> => rank split |abcde>
        the |sp>
            |a> + 2|b> + 3|c> + 4|d> + 5|e>

        clean the |sp>
            |a> + |b> + |c> + |d> + |e>

    see also:
        clean