title: In R 2.14.1, what does wrong sign in 'by' argument mean?
body: <p>Here is my code</p>
  
  <pre><code>slidingwindowplotATGC = function(windowsize, inputseq) 
  {
  
  starts = seq(1, length(inputseq)-windowsize, by = windowsize)
  n = length(starts)
  chunkGs = numeric(n)
  chunkAs = numeric(n)
  chunkTs = numeric(n)
  chunkCs = numeric(n)
  for (i in 1:n) { 
      chunk = windowsize[starts[i]:(starts[i]+9999)]
      chunkG = sum("g" == chunk)/length(chunk)
      chunkA = sum("a" == chunk)/length(chunk)
      chunkT = sum("t" == chunk)/length(chunk)
      chunkC = sum("c" == chunk)/length(chunk)
    chunkGs[i] = chunkG
      chunkAs[i] = chunkA
    chunkTs[i] = chunkT
    chunkCs[i] = chunkC
  }   
  plot(starts,chunkGs,type="b",ylim=c(min(min(chunkAs),min(chunkTs),min(chunkCs),min(chunkGs)),max(max(chunkAs),max(chunkTs),max(chunkCs),max(chunkGs))),col = "red")
  points(starts,chunkTs,col = "blue")
  points(starts,chunkAs,col = "green")
  points(starts,chunkCs)
  </code></pre>
  
  <p>}</p>
  
  <p>Im getting the following error message,</p>
  
  <pre><code>Error in seq.default(1, length(inputseq) - windowsize, by = windowsize) : 
    wrong sign in 'by' argument
  </code></pre>
  
  <p>which I never got before when running codes of this sort, infact I re ran old code that worked perfectly before, except this time Im getting this error message which doesn't seem to make any sense at all! I need help with this before I go completely insane... Maybe Im just bad at this program, but it seems to me that it has a mind of its own... I was also getting an error message before regarding the ylim function, stating that it needed to be a finite value, which is what I was giving it? HELP!!!</p>