title: png terminal not working gnuplot in OS X 10.8.4
body: <p>I have started using gnuplot in my macbook pro. I am using OS X 10.8.4. Whenever I set terminal to png using </p>
  
  <blockquote>
    <p>set term png</p>
  </blockquote>
  
  <p>it gave an error as follow:
  unknown or ambiguous terminal type; type just 'set terminal' for a list</p>
  
  <p>Does somebody know it?</p>