Matlab实现——Recursive Trapezoidal Rule

 rctrap.m

%Program 7.3 (Recursive Trapezoidal Rule).function T=rctrap(f,a,b,n,tol)%Input    - f is the integrand input as a string ’f’%   - a and b are upper and lower limits of integration%   - n is the number of times for recursion%   -tol is the tolerance%Output  - T is the recursive trapezoidal rule listM=1;h=b-a;T=zeros(1,n+1);T(1)=h*(feval(f,a)+feval(f,b))/2;err=1;while(err>tol)    for j=1:n         M=2*M;         h=h/2;         s=0;         for k=1:M/2            x=a+h*(2*k-1);            s=s+feval(f,x);         end         T(j+1)=T(j)/2+h*s;         err=abs(T(j)-T(j+1));    endend

fun.m

function f=fun(x)f=2*x-x.^2;

untitled.m

a=0;b=2;n=20;tol=5*10e-6;f='fun';T=rctrap(f,a,b,n,tol)