From: DBRS28A@prodigy.com (Mr. Gerald A. Sabin) Newsgroups: sci.math Subject: Re: Please help me about Bairstow method Date: 29 Jul 1998 14:16:36 GMT Bairstow's method for finding roots of a polynomial starts out by assuming a value for a quadratic factor of the polymonial. Then checks to see 'how closely' this quadratic factor divides into the polynomial. The 'adjusts the coefficients' of the quadratic factor and checks again for 'how closely' it divides... This is done repeatedly until 'how closely' is 'close enough'. The quadratic factor that fits now has two of the roots of the polynomial. The pair of roots may real, or complex. Divide the quadratic factor into the polynomial and obtain a 'reduced polynomial'; the original degree N is now N-2. Procedure is repeated to look for the next quadratic factor. Should have mentioned that if the degree of the original is ODD, then there will be at least one real root. This one real root is found by successive approximation. Bairstow's method can be readily prepared as a program in QBASIC. After that, you can solve for the roots of polynomials all day long. -Jerry 29 July 98 1015AM -0400 email: Jerry_Sabin.NOSPAM@prodigy.com (remove .NOSPAM)