explicitly casting return value of avg() to float4

Is the preferred way to return the average of ::float4 values to
explicitly cast the returned value of avg() to ::float4?

If so, how do people deal with this in end user apps?  Do you check to
see whether the column is ::float8 or ::float4 and then use a different
SQL statement?  Ugh, I hope not.

main_v0_8=# select version();
                            version
-------------------------------------------------------------
  PostgreSQL 7.2.1 on i686-pc-linux-gnu, compiled by GCC 2.96
(1 row)

main_v0_8=# select avg(0.01::float4);
          avg
---------------------
  0.00999999977648258
(1 row)

main_v0_8=# select avg(0.01::float4)::float4;
  avg
------
  0.01
(1 row)


--

-**-*-*---*-*---*-*---*-----*-*-----*---*-*---*-----*-----*-*-----*---
  Jon Lapham
  Extracta Moléculas Naturais, Rio de Janeiro, Brasil
  email: lapham@extracta.com.br      web: http://www.extracta.com.br/
***-*--*----*-------*------------*--------------------*---------------