secant

代码说明：

  In numerical analysis, the secant method is a root-finding algorithm that uses a succession of roots of secant lines to better approximate a root of a function f.(The secant iteration to find the zero of some non-linear function converges to zero if appropriate starting values are chosen. Although the convergence rate is not as good as the one of the Newton method, it may sometimes converge when Newton fails. The funtion should be defined as an inline function and two starting values are required to start the iteration. Please enter help secant from the Matlab prompt for usage information and examples. )