Numeric integration with Trapezoidal and Simpson's rule

I am trying to write a code that allows a user pick between Trapezodal and simpsons method of integration and then after picking the code will let the integrate a given formula 𝑦 = 𝑥 −1 + √𝑥𝑒 ^x . My code is not running however and i was wondering where I may be going wrong

clc

clear

%Lower limit (a)

a = input('What is your lower limit (a)? \n');

% Upper limit (b)

b = input('What is your upper bound (b)? \n');

% Subintervals, it is an even number

N = input('How many subintervals (N)? \n');

%y=1./x+ sqrt(x).*exp(x);

% Calculating the integral

clear

clc

function s=simprl(f,a,b,N)

h=(b-a)/N;

s1=0;

s2=0;

for i=1:N

x=a+h*(2*i-1);

s1=s1+f(x);

end

for i=1:(N-1)

x=a+h*2*i;

s2=s2+f(x);

end

s=h*(f(a)+f(b)+4*s1+2*s2)/3; %composite simpsons formula without error

fprintf('s =%f\n',simprl)

end

[VBBV]

Is f a function ? or vector ? it seems you are trying to pass function as argument to a function

Answer 1

[Jon]

You may have other problems too, but it looks like you clear all of your variables right after you just defined your limits and number of subintervals. You should not have the lines of code

% Calculating the integral
clear
clc

[Jon]

Also you seem to define a function simprl to compute an integral but you never call the function. The function won't run unless you call it somewhere in your code.

[Jhonie Habimana]

Thank you so much I will implement this immediately, how do I call a function

[Jon]

In general if you have a function, lets call it myfun with for example arguments a,b,c that returns one argument then somewhere in your code you would just use for example

% just an illustrative example
a = 2
b =26.3
c = 15
y = myfun(a,b,c)

In your case it is a little more complicated because the first argument to your function is a function. (the integrand) You need to pass a handle to that function. See https://www.mathworks.com/help/matlab/matlab_prog/pass-a-function-to-another-function.htmlHere's one way to do it

% assuming a,b, and N are defined earlier in your code, then use
f = @(x) 1./x+ sqrt(x).*exp(x);
y = simprl(f,a,b,N)