Basic principles

Having made the dependence of ub on Uh explicit in (2.14), we can go back

to (2.6) and take VA — ^h] inserting (2.7) and (2.14) we obtain:

{find Uh G Vh such that : (2.15) C{uh,vh) + J2K £{LB K (f - Luh),vh) = {f,vh), Vvh € Vh.