In this paper, numerical solution of third order integro-differential equation with boundary conditions is given utilizing Haar collocation technique. Both nonlinear and linear integro-differential equations are solved using this method. The third order derivative is approximated using Haar functions in both nonlinear and linear integro-differential equations. Integration is used to obtain the expression of lower order derivatives as well as the solution for the unknown function. The Gauss elimination approach is utilized for linear systems and Broyden approach is adopted for nonlinear systems. Validation and convergence of the proposed approach are illustrated using some examples. At various collocation and gauss points, the maximum absolute and root mean square errors are compared to the exact solution. The convergence rate is also measured using different numbers of nodal points, and it is nearly equal to $2$.

本文利用Haar配点技术给出了带边界条件的三阶积分微分方程的数值解。非线性和线性积分微分方程都可以用这种方法求解。在非线性和线性积分微分方程中都使用Haar函数来近似三阶导数。积分用于获得低阶导数的表达式以及未知函数的解。高斯消除方法用于线性系统，而Broyden方法用于非线性系统。使用一些示例说明了所提出方法的验证和收敛性。在各种搭配和高斯点，将最大绝对误差和均方根误差与精确解进行比较。$\mathrm{2个}$。