secant.m

关于数值计算的matlab程序代码,包含了很多的实用的算法.程序全部可以直接用的,有详细的英文注释.

function [p1,err,k,y]=secant(f,p0,p1,delta,epsilon,max1)

%Input - f is the object function input as a string 'f'
%      - p0 and p1 are the initial approximations to a zero of f        
%	    - delta is the tolerance for p1
%	    - epsilon is the tolerance for the function values y
%	    - max1 is the maximum number of iterations
%Output - p1 is the secant method approximation to the zero
%	     - err is the error estimate for p1
%	     - k is the number of iterations
%	     - y is the function value f(p1)

%  NUMERICAL METHODS: Matlab Programs
% (c) 2004 by John H. Mathews and Kurtis D. Fink
%  Complementary Software to accompany the textbook:
%  NUMERICAL METHODS: Using Matlab, Fourth Edition
%  ISBN: 0-13-065248-2
%  Prentice-Hall Pub. Inc.
%  One Lake Street
%  Upper Saddle River, NJ 07458

for k=1:max1	
	p2=p1-feval(f,p1)*(p1-p0)/(feval(f,p1)-feval(f,p0));	
	err=abs(p2-p1);
	relerr=2*err/(abs(p2)+delta);
	p0=p1;
	p1=p2;
	y=feval(f,p1);
	if (err<delta)|(relerr<delta)|(abs(y)<epsilon),break,end
end