4th order equation method (Brown method) by floating decimal point operation

Abstract

When solving 4th order equation by floating decimal point operation, there is Ferrari method famous as a solution method of 4th order equation. In this paper, we apply Brown method that transform 4th order equation into the product of two 2nd order equations directly to floating point operation and propose the effective computation method. And from the relation of coefficient and solution of 4th order equation, we express coefficients and all numerical values in the middle calculation with four solutions, and by analyzing the information on the solutions contained in those coefficients, we show the validity of the Brown method.