Primero, convierta la matriz en un conjunto usando unnest:
> SELECT n FROM unnest(ARRAY[1.53224,0.23411234]) AS n;
n
------------
1.53224
0.23411234
(2 rows)
Luego, aplique una expresión a la columna:
> SELECT ROUND(n, 2) FROM unnest(ARRAY[1.53224,0.23411234]) AS n;
round
-------
1.53
0.23
(2 rows)
Finalmente, use array_agg para volver a convertir el conjunto en una matriz:
> SELECT array_agg(ROUND(n, 2)) FROM unnest(ARRAY[1.53224,0.23411234]) AS n;
array_agg
-------------
{1.53,0.23}
(1 row)