Appending arrays in a table - Mailing list pgsql-sql

Let's say I have a table foobar with an element data of type float4[]
array. If I insert 100 values of data into the float4 array, can I then
append an additional 50 values at the end of the original 100 value
float4[] array within the table? Is there anything like an UPDATE APPEND
statement?

Thanks.
-Tony Reina