converting float4 to float8 - Mailing list pgsql-sql

I'm trying to get a query to return a float8 for a field defined as
float4.  When I use

select cast(attname as float8) from table1;

I get the error:

ERROR:  function ftod(float4) does not exist

Any ideas how I can do this?  I'm trying to use this select in an
"insert into" statement where the target table needs to have the
target field defined as float8.

--
William D. McCoy
Geosciences
University of Massachusetts
Amherst, MA  01003