opclass for real[] - Mailing list pgsql-general

Hi,
I have a column real[] in my table. I need to create a gist index on
it. But the error is obvious as follows.

ERROR:  data type real[] has no default operator class for access
method "gist"
HINT:  You must specify an operator class for the index or define a
default operator class for the data type.

Is there a opclass defined in 8.2 or I have to create one. In either
case can you please give a link for information on opclasses.

Thanks
Abhang