Isoparametric mesh

Hello evryone,

I am trying to figure out how to implement an iso-parametric mesh. By that I mean that my boundaries are curved and that I am seeking for an integral computation within mass and stifness matrices that takes the curves into account, and doesn’t consider the curved geometry as a set of small linear segments defined by a set of boundary nodes deduced from the initial curve introduced as an input when defining mesh boundaries.
More precisely, If I define the boundary by circle, I need the integrals on the boundary elements to take the curved edge into account, and not replace it by a line.