Determining return type in Perl/MySQL

[Gregg Allen]

I have a complex,  prewritten subroutine that is supposed to return a 
numeric value from a MySQL database table.  it actually works quite 
well, most of the time, but sometimes it returns an undefined value, a 
non-numeric value, or basically anything except a valid numeric value.

This is OK in the sense that it just means they are records to be 
ignored, but I am having trouble figuring out how to determine if it is 
just a simple numeric value or a string or null, or whatever, so I can 
decide how to process it.

Any Suggestions?

Thanks in Advance,

Gregg Allen