In fifth line, H(e<sup>j(½)π</sup>) rather than H(e<sup>j(½)πn</sup>), so that corrected equation is y<sub>1</sub>[x] = H(e<sup>j0</sup>)e<sup>j0n</sup> + H(e<sup>j(½)π</sup>)e<sup>j(½)πn</sup>.