Author/Authors :
PEYGHAN، E نويسنده Department of Mathematics, Faculty of Science, University of Arak, Arak, I. R. of Iran , , RAZAVI، A نويسنده Department of Mathematics and Computer Science, Amirkabir University, Tehran, I. R. of Iran , , HEYDARI، A نويسنده Faculty of Science, Tarbiatmodares University, Tehran, I. R. of Iran ,