hamming.m

来自「数值计算方法的教程」· M 代码 · 共 52 行

function H=hamming(f,T,Y)

%Input    - f is the function 
%            - T is the vector of abscissas
%            - Y is the vector of ordinates
%Remark.  The first four coordinates of T and Y must
%               have starting values obtained with RK4
%Output - H=[T' Y'] where T is the vector of abscissas and
%              Y is the vector of ordinates

% If f is an M-file function call H=hamming(@f,T,Y).
% If f is an anonymous function call H=hamming(f,T,Y).

%  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

n=length(T);
if n<5, return, end;

F=zeros(1,4);
F=f(T(1:4),Y(1:4));
h=T(2)-T(1);
pold=0;
cold=0;

for k=4:n-1
   
   %Predictor
   pnew=Y(k-3)+(4*h/3)*(F(2:4)*[2 -1 2]');
   
   %Modifier
   pmod=pnew+112*(cold-pold)/121;
   T(k+1)=T(1)+h*k;
   F=[F(2) F(3) F(4) f(T(k+1),pmod)];
   
   %Corrector
   cnew=(9*Y(k)-Y(k-2)+3*h*(F(2:4)*[-1 2 1]'))/8;
   Y(k+1)=cnew+9*(pnew-cnew)/121;
   pold=pnew;
   cold=cnew;
   F(4)=f(T(k+1),Y(k+1));
end

H=[T' Y'];