Update Query in SQL Server using a View as source

I have a view that I want to use to update a field in a table. The view is pulling data from this table and then I am doing some calculations to change the values. Now I want to take that new value from the view and update it back into this table's field. How do I use a view as the source for a update query? This view is also joined with other tables because it needs other data to do these calculations. Just not sure how to write the update query to use the view as the source.