create a function using simpsons rule in matlab

main.m
function I = simpsons_rule(f,a,b,n)
% This function calculates the definite integral of a function f using 
% Simpson's rule, between the limits of integration a and b and using n 
% subintervals.
% Inputs:
% f - the function to be integrated
% a, b - the limits of integration
% n - the number of subintervals (must be an even number)
% Output:
% I - the value of the definite integral

x = linspace(a,b,n+1); % Generate the equally spaced points 
h = x(2)-x(1); % Determine the width of the subintervals

% Simpson's Rule formula
I = (h/3) * (f(x(1))+f(x(n+1)) + 4*sum(f(x(2:2:n))) + 2*sum(f(x(3:2:n-1))));
end
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