Get Accumulated Depreciation in PostgreSQL Function

-- select * from fnt_get_depreciation_acum('20190620', '20190930', 244685.29, 10);

-- select * from tmp_asset_periods;

create or replace function fnt_get_depreciation_acum(p_activationdate date, p_enddate date, p_asset_value numeric(20,2), p_uselifeyears numeric(10,2))
returns numeric(20,2)
as $$
declare
    v_depreciation_value numeric(20,2) = 0.00;
    v_qty_period int = (p_uselifeyears * 12);
   
    v_dep_date date = p_activationdate;
    v_yearno int = 0;
    v_monthno int = 0;

    v_enddate date = p_enddate;
    v_current_year int = 0;
    v_current_month int = 0;

    v_current_period int = 0;
    v_depreciation_acum numeric(20,2) = 0.00;
    v_current_dep_acum numeric(20,2) = 0.00;
begin
    v_depreciation_value =
    coalesce((
        p_asset_value / v_qty_period
    ), 0.00);

    drop table if exists tmp_asset_periods;

    create temporary table tmp_asset_periods
    as
    select
        1::int periodno,
        now()::date as dep_date,
        0.00::numeric(20,2) as dep_amt,
        0.00::numeric(20,2) as dep_acum;
   
    truncate table tmp_asset_periods;

    for k in 1..v_qty_period loop
        v_yearno = extract(year from v_dep_date);
        v_monthno = extract(month from v_dep_date);
   
        v_current_year = extract(year from v_enddate);
        v_current_month = extract(month from v_enddate);
       
        if(k = v_qty_period)then
            v_depreciation_value = p_asset_value - v_depreciation_acum;
        end if;
   
        v_depreciation_acum = v_depreciation_acum + v_depreciation_value;
       
        insert into tmp_asset_periods
        select
            k,
            v_dep_date,
            v_depreciation_value,
            v_depreciation_acum;
       
        v_dep_date = p_activationdate + (k::varchar || ' month'::varchar)::interval;
       
        if((v_yearno = v_current_year) and (v_monthno = v_current_month))then
            v_current_period = k;
            v_current_dep_acum = v_depreciation_acum;
        end if;
    end loop;

    return v_current_dep_acum;
end;
$$ language plpgsql;