CREATE TABLE t
(
    yf float,
    yd decimal
);

INSERT INTO t (yf,yd)
VALUES (1.0, 1.0),
       (20.0, 20.0),
       (25.0, 25.0),
       (41.0, 41.0),
       (55.5, 55.5),
       (60.9, 60.9),
       (72.0, 72.0),
       (88.0, 88.0),
       (88.0, 88.0),
       (89.0, 89.0);

select sqrdiff(yf)     as sqrdiff_float,
       sqrdiff(yd)     as sqrdiff_decimal,
       var_pop(yf)     as var_pop_float,
       var_pop(yd)     as var_pop_decimal,
       var_samp(yf)    as var_samp_float,
       var_samp(yd)    as var_samp_decimal,
       stddev_pop(yf)  as stddev_pop_float,
       stddev_pop(yd)  as stddev_pop_decimal,
       stddev_samp(yf) as stddev_samp_float,
       stddev_samp(yd) as stddev_samp_decimal
from t;

-- returns

    sqrdiff_float   | sqrdiff_decimal |   var_pop_float   | var_pop_decimal |  var_samp_float   | var_samp_decimal | stddev_pop_float  |  stddev_pop_decimal   | stddev_samp_float |  stddev_samp_decimal
--------------------+-----------------+-------------------+-----------------+-------------------+------------------+-------------------+-----------------------+-------------------+------------------------
  8885.844000000001 |        8885.844 | 888.5844000000001 |        888.5844 | 987.3160000000001 |          987.316 | 29.80913282871543 | 29.809132828715430446 | 31.42158493774622 | 31.421584937746218024
(1 row)

-- Note that the results for floats and decimals are the same and these values correspond to what PG returns.

select sqrdiff(yf) over (order by yf)     as sqrdiff_float,
       sqrdiff(yd) over (order by yd)     as sqrdiff_decimal,
       var_pop(yf) over (order by yf)     as var_pop_float,
       var_pop(yd) over (order by yd)     as var_pop_decimal,
       var_samp(yf) over (order by yf)    as var_samp_float,
       var_samp(yd) over (order by yd)    as var_samp_decimal,
       stddev_pop(yf) over (order by yf)  as stddev_pop_float,
       stddev_pop(yd) over (order by yd)  as stddev_pop_decimal,
       stddev_samp(yf) over (order by yf) as stddev_samp_float,
       stddev_samp(yd) over (order by yd) as stddev_samp_decimal
from t;

-- returns:

sqrdiff_float    |       sqrdiff_decimal       |   var_pop_float   |    var_pop_decimal    |   var_samp_float   |   var_samp_decimal    |  stddev_pop_float  |  stddev_pop_decimal   | stddev_samp_float  |  stddev_samp_decimal
---------------------+-----------------------------+-------------------+-----------------------+--------------------+-----------------------+--------------------+-----------------------+--------------------+------------------------
                   0 |                           0 |                 0 |                     0 | NULL               | NULL                  |                  0 |                     0 | NULL               | NULL
               180.5 |                       180.5 |             90.25 |                 90.25 |              180.5 |                 180.5 |                9.5 |                   9.5 | 13.435028842544403 | 13.435028842544402964
   320.6666666666667 | 1563.5500000000000000000001 | 106.8888888888889 | 52.738888888888888889 | 160.33333333333334 | 79.108333333333333333 | 10.338708279513883 | 7.2621545624483157849 | 12.662279942148386 | 8.8942865556116041596
              814.75 | 1563.5500000000000000000001 |          203.6875 |               163.075 |  271.5833333333333 | 217.43333333333333333 | 14.271912976192084 | 12.770082223697700217 | 16.479785597310826 | 14.745620818851043999
                1726 |        57131586605212041.25 |             345.2 |                312.71 |              431.5 |              390.8875 | 18.579558659989747 | 17.683608229091708760 |  20.77257807784099 | 19.770875043861867471
              2600.8 | 13317.319002524018247997853 | 433.4666666666667 | 145.82459565876494609 |  520.1600000000001 | 174.98951479051793531 | 20.819862311424316 | 12.075785508974765907 | 22.807016464237492 | 13.228360245718965727
  3845.0371428571434 |  1859.455475739525896765693 | 549.2910204081634 | 190.24741432177168926 |  640.8395238095239 | 221.95531670873363747 | 23.436958429117105 | 13.793020493052697892 | 25.314808389745398 | 14.898164877216711669
   7527.842222222223 |  18594.55475739525896765693 | 836.4269135802471 | 557.17077551305346554 |  940.9802777777779 | 626.81712245218514873 | 28.921046204801222 | 23.604465160495661304 |  30.67540183563661 | 25.036316071902134954
   7527.842222222223 |  18594.55475739525896765693 | 836.4269135802471 | 557.17077551305346554 |  940.9802777777779 | 626.81712245218514873 | 28.921046204801222 | 23.604465160495661304 |  30.67540183563661 | 25.036316071902134954
   8885.844000000001 |  1859.455475739525896765693 | 888.5844000000001 | 185.94554757395258968 |  987.3160000000001 | 206.60616397105843297 |  29.80913282871543 | 13.636185228059663963 |  31.42158493774622 | 14.373801305537044085
(10 rows)