Purpose – The purpose of this paper is to solve the population balance equations, by applying rationalized Haar functions, described by stretched differential equation. Design/methodology/approach – An illustrative example is given and numerical results are compared with Block-Pulse, Wavelet-Galerkin and Shifted-Legendre methods. Findings – The results show the superiority of this method in comparison with the Block-Pulse and the weighted residual methods. Originality/value – The paper is of value in introducing the scaled operation matrix and also the method is straightforward and suitable for digital computation.
