How to make a function operate on a vector of arbitrary length

I have written a function to compute the factorial of a positive integer and return error results if something that isn't a positive integer is input into the function. However, I need to extend this so that the function can be applied to a vector of any length and will find the factorial of each element individually. How do I go about doing this?

function s = sfactorial(x)
  if x < 0
      error('x must be positive')
  elseif floor(x) ~= x
      error('x must be an integer')
  else
      result=1;
      for i = 1:x
         result=result*i;
      end
  end
  result

Answer 1

[Stephan]

function s = sfactorial(x)
  if x < 0
      error('x must be positive')
  elseif floor(x) ~= x
      error('x must be an integer')
  else
      result=ones(1,numel(x));
      for k = 1:numel(x)
        for i = 1:x(k)
            result(k) = result(k)*i
        end
      end
  end
  s = result;
end