title: TypeError: 'numpy.float64' object is not callable
body: <p>So, what im trying to do is get certain numbers from certain positions in a array of a given > range and put them into an equation</p>
  
  <pre><code>yy = arange(4)
  xx = arange(5)
  Area = ((xx[2] - xx[1])(yy[2] + yy[1])) / 2
  </code></pre>
  
  <p>I try to run it and I get this..</p>
  
  <pre><code>----&gt; ((xx[2] - xx[1])(yy[2] + yy[1])) / 2
  TypeError: 'numpy.int64' object is not callable
  </code></pre>
  
  <p>I get error.. how can I use certain numbers in an array and put them into an equation?</p>