Abstract
In this paper, We solved the system of differential-algebraic equation (DAEs) of index one numerically with Heun's method and operational matrices of Haar wavelet method, When we compared the results of the two methods with the exact solution, show that the operational matrices of Haar wavelet method is more efficiency and it's numerical results near to the exact solution more than the Heun's method, and the solution accuracy of this method is increasing and the error decreases when the number of mesh points and size of matrices increase.
