1. Forsythe G. E. and Moler C. B. Computer Sohltion of Linear Algebraic Systems; Prentice Hall Englewood Cliffs N.J. pp. 115 and 68. Forsythe G. E. and Moler C. B. Computer Sohltion of Linear Algebraic Systems; Prentice Hall Englewood Cliffs N.J. pp. 115 and 68.