title: R issue "object not found"
body: <p>I am a newcomer to R. Last week I had a long and complicated function working perfectly. The program was letting me pick a subset of columns and doing various manipulations on that subset. The function must work 'function(arg1=first_header_name, arg2=second_header_name,....)'. I have cleared the console, removed the old history file. I have read the manual again, I have checked the .csv file to make sure everything there is still the same. I have gone back and reworked it all step by step and I have the place where this new problem occurs. As it is a very long function, I am only going to reproduce it in a simplified version of the part that is suddenly not working.</p>
  
  <pre><code> elbow &lt;- function(arg1,arg2) {
     my_data &lt;- read.csv("data.csv", header=TRUE, sep=",") 
     average_A &lt;- (arg1 + arg2)
     average_A
   }
   elbow(A3,A5)
   # Error in elbow(A3, A5) : object 'A3' not found
  </code></pre>
  
  <p>Column headers are A3,A4,A5,A7,A8,A9,B2,B3,B5,B6,B7,B9</p>
  
  <p>What stupid little error am I making? This is driving me batty. It has to be something trivial.</p>