traprl.m

来自「国外计算机科学教材系列 numerial method using matla」· M 代码 · 共 27 行

function s=traprl(f,a,b,M)

%Input    - f is the integrand input as a string 'f'
%         - a and b are upper and lower limits of integration
%         - M is the number of subintervals
%Output   - s is the trapezoidal rule sum

% NUMERICAL METHODS: MATLAB Programs
%(c) 1999 by John H. Mathews and Kurtis D. Fink
%To accompany the textbook:
%NUMERICAL METHODS Using MATLAB,
%by John H. Mathews and Kurtis D. Fink
%ISBN 0-13-270042-5, (c) 1999
%PRENTICE HALL, INC.
%Upper Saddle River, NJ 07458

h=(b-a)/M;
s=0;

for k=1:(M-1)
   x=a+h*k;
   s=s+feval(f,x);
end

s=h*(feval(f,a)+feval(f,b))/2+h*s;