Defining x as a symbol

Hi (:

This is my code. It calculates Simpson's rule The problem is that when I run it, it comes up with "Undefined function or variable 'x'" Now, I KNOW that I have to define x as a symbol, and have done so in my code, however I still get this error message. The only way my function works is if I define x as a symbol in the command window before running it.

How can I incorporate syms x into my function?

fun = a function

x0 = lower limit of integration

xn = upper limit of integration

n = steps

function result = simpson( fun,x0,xn,n )
  %The function calculates an approximation for the integral using Simpson's
  %rule.

  syms x
  f(x) = fun;
  h = (xn-x0)/(n);
  result = sum(f(x0)+f(xn));

  for ii = x0+h:2*h:xn-h;  
    nresult = 4*f(ii);  
    result=sum(result+nresult);  
  end

  for ii = x0+2*h:2*h:xn-h;  
    nresult = 2*f(ii);  
    result=sum(result+nresult);  
  end

  result = (h/3)*result;
end

Answer 1

[Image Analyst]

I'm not seeing it. Exactly where did you assign a value to x, such as

x = whatever;

It thinks f is an array and when you do f(x) it wants a number for x, which you have not assigned, so it can't get the x'th element of f so that's why it gives that error (which you actually forgot to post). Please post all the red text, don't just snip out a tiny portion of the error message and expect to get our best suggestions.