Numerical solution of the linear two-dimensional Fredholm integral equations of the second kind via two-dimensional triangular orthogonal functions

In this paper, we will give some results for developing the two-dimensional triangular orthogonal functions (2d-tfs) for numerical solution of the linear two-dimensional fredholm integral equations of the second kind. the product of 2d-tfs and some formulas for calculating definite integral of them are derived and utilized to reduce the solution of two-dimensional fredholm integral equation to the solution of algebraic equations. also a theorem is proved for convergence analysis. numerical examples are presented and results are compared with analytical solution to demonstrate the validity and applicability the method.