Need a cumulative field in a table

Question

Database: Sybase ASE 15.0.3

Tables:

authors(int author_id, varchar(20) author_name)
books(int author_id,int number_of_pages)

I need to add a new field to the table "authors" for total_number_of_pages (the sum of the number of pages for all the books written by the author).

Can this be done by a (possibly materialized) computed field?

I don't like the idea of a view, I really would prefer the field to be in the table authors, if possible.